Veterinary Advice Online: Neutering Cats Feline Neutering.



This is an image of a cat's testicles just prior to feline neutering or desexing surgery.Male cat neutering, otherwise known as sterilisation, "fixing", desexing, castration (castrating) or by its correct veterinary name: orchiectomy (also termed gonadectomy), is the surgical removal of a male cat's testicles for the purposes of feline population control, medical health benefit, genetic-disease control and behavioral modification. Considered to be a basic component of responsiblecat ownership, the neutering of male cats is a simple and common surgical procedure that is performed by most veterinary clinics all over the world. This page contains everything you, the pet owner, need to know about feline neutering (male cat desexing). Neutering topics are covered in the following order:

1. What is neutering?

2. Neutering pros and cons - the reasons for and against neutering cats.
2a. The benefits of neutering (the pros of neutering) - why we neuter cats.
2b. The disadvantages of desexing (the cons of desexing) - why some choose not to neuter cats.

3. Information about neutering age: when to neuter a cat.
3a. Current desexing age recommendations.
3b. Neutering kittens - information about the early spay and neuter of young cats (kitten desexing).


4. Neutering procedure (desexing surgery) - a step by step pictorial guide to feline neutering surgery.

5. Neutering after-care - all you need to know about caring for your tomcat after neutering surgery.
Includes information on feeding, bathing, exercising, wound care, pain relief and stopping cats from licking surgical wounds.

6. Possible surgical and post-surgical complications of neutering cats.
6a. Pain after surgery (e.g. cat walking stiffly, not wanting to sit down and so on).
6b. Swollen, bruised, blood-filled scrotum after surgery.
6c. Wound infection.
6d. Penis and/or urethra laceration.
6e. Excessive wound hemorrhage (excessive bleeding during or after surgery).
6f. Failure to ligate (tie off) the testicular blood vessels adequately.
6g. Post-operative renal failure (kidney failure).
6h. Anaesthetic death.
6i. Tracheal damage in cats caused by overinflation of ET (endotracheal) tubes.


7. Late complications of neutering cats.
7a. Weight gain.
7b. Preputial scalding and infection - a potential complication of early underage desexing.
7c. The neutering didn't deliver the change (improvement) in male behavior that you thought it would (i.e. behavioral problems such as aggression, dominance, marking territory (urine spraying) and roaminghave persisted despite desexing).


8. Frequently asked questions (FAQs) and myths about neutering cats:
8a. Myth 1 - All desexed toms gain weight (get fat).
8b. Myth 2 - Desexed male cats become lazy and lose their drive to hunt mice, rats and vermin.
8c. Myth 3 - Without his testicles, a male cat won't feel like himself (i.e. he "won't be a man").
8d. Myth 4 - Male cats need to have sex before being desexed.
8e. Myth 5 - Male cats should be allowed to father (sire) a litter before desexing.
8f. Myth 6 - Vets just advise neutering for the money not for my cat's health.
8g. FAQ 1 - Why won't my veterinarian clean my cat's teeth at the same time as desexing him?
8h. FAQ 2 - Why shouldn't my vet vaccinate my cat whilst he is under anaesthetic?
8i. FAQ 3 - Is desexing safe? It's just a routine procedure isn't it?
8j. FAQ 4 - My veterinarian offered to perform a pre-anaesthetic blood screening test - is this necessary?
8k. FAQ 5 - When is feline desexing surgery not safe to perform?


9. The cost (price) of neutering cats:
9a. The typical cost of neutering a tom cat at a veterinary clinic.
9b. Where and how to source low cost and discount feline neutering.
9c. Free feline neutering.


10. Alternatives to neutering your male cat:
10a. Feline birth control method 1 - separate the tom from the queen and prevent him from roaming.
10b. Feline birth control method 2 - spay your female cat.
10c. Feline birth control method 3 - "the pill" and hormonal female oestrous (heat) suppression.
10d. Feline birth control method 4 - inducing ovulation to suppress feline estrus (heat).
10e. Feline birth control method 5 - feline vasectomy.
10f. Feline birth control method 6 - chemical castration - injecting sclerosing agents into the testicles.
10g. Anti-testosterone agents to reduce testosterone-related medical and behavioral problems.




WARNING - IN THE INTERESTS OF PROVIDING YOU WITH COMPLETE AND DETAILED INFORMATION, THIS SITE DOES CONTAIN MEDICAL AND SURGICAL IMAGES THAT MAY DISTURB SOME READERS.







1. What is neutering?

Neutering is the surgical removal of a male (tom) cat's testicles. During the procedure, each of the cat's testes and testicular epididymi are removed along with sections ofthe feline's testicular blood vessels and spermatic ducts (vas deferens or ductus deferens).The remainder of the male cat's reproductive tract structures: the prostate, bulbourethral gland, urethra, penis and much of the cat's testicular blood vessels and spermatic ducts,are left intact. Basically, the parts of the male reproductive tract that get removed are those which are responsible for sperm production, sperm maturation and the secretion of testosterone (the majormale hormone). Removal of these structures plays a big role in feline population control(without sperm, the tomcat can not father young); genetic disease control (male cats withgenetic disorders can not pass on their inheritable disease conditions to any young if they can not breed); preventionand/or treatment of various medical disorders (e.g. castration prevents and/or treats a number of testicular diseases and testosterone-enhanced medical conditions) and male cat behavioral modification (testosterone is responsible for many tomcat behavioral traits that some owners findproblematic - e.g. roaming, aggression, inter-male aggression, dominance, urine spraying - andcastration, by removing the source of testosterone, may help to resolve these issues).



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2. Neutering pros and cons - the reasons for and against feline neutering.

2a. The benefits of neutering (the pros of neutering) - why we neuter male cats.

There are many reasons why veterinarians and pet advocacy groups recommend the neutering ofentire male tomcats. Many of these reasons are listed below, however the list is byno means exhaustive.

1. The prevention of unwanted litters:
A litter of 3-week-old kittens dumped at a shelter in Australia. This was one of hundreds of feline litters dumped in that one shelter that year.Pet overpopulation and the dumping of unwanted litters of kittens (and puppies) is anall-too-common side effect of irresponsible pet ownership. Every year, thousands of unwanted kittens and older cats are surrendered to shelters and pounds for rehoming or dumped on the street (street-dumped animals ultimately end up dying from neglect, predation or transmissiblefeline diseases like FIV or finding their way into pounds and shelters that may or may not beable to find homes for them). Many of these animals do not ever get adopted from the pounds and shelters that take them in and need to be euthanased. This sad waste of healthy life can be reduced by not letting pet cats breed indiscriminately and one way of preventing any accidental, unwanted breeding from occurring is through the routine neutering of all non-stud (non-breeder) male tomcats (and female cats too, but this is another page).

Author's note: The deliberate breeding of family pets should never be considered aneasy way to make a quick buck. A lot of cost and effort and expertise goes into producing a quality litter for profitable sale. And that's only if nothing goes wrong! If your queenneeds a caesarean section at one in the morning or develops a severe infection after queening (e.g. pyometron, mastitis), then all of your much planned profits will rapidly turn into financial losses (the vet fees for these kinds of treatments are high). On top of that, if you fail to do your homework and breed poor quality kittens or poorly socialisedkitties that won't sell, then you've just condemned some of those young animals to a miserablelife of being dumped in shelters or on the streets.

2. The reduction of stray and feral animal populations:
A spotted pardalote killed by a feral cat.By having companion tomcats neutered at young ages, they are unable to go out and mate with feral or stray queens and get them pregnant. This results in fewer litters of stray and feral cats being bornwhich, in return, benefits not just those unwanted kittens (who lead a tough neglected life), butalso society and the environment in general. Feral and stray cat populations pose a significant risk of predation to native wildlife (see image on right - just one of millions of such occurrences); they carry diseases that may affect humans (e.g. rabies, worms) and their pets (e.g. rabies, FIV, FIA, FeLV, parasites); they fight withdomestic pets, giving them nasty cat-fight infections and abscesses; they steal the foodof domestic pets and they place a huge financial and emotional burden on pounds, shelters and animal rescue groups.

3. To reduce the spread of inferior genetic traits, genetic diseases and congenital deformities:
Cat breeding is not merely the production of kittens, it is the transferral of genes and genetic traits from one generation to the next in a breed population. Petowners and breeders should desex male tom cats that have conformational, coloring and temperamental traits,which are unfavourable or faulty to the breed as a whole, to reduce the spread of thesedefects further down the generations. Male cats with heritable genetic diseases andcongenital defects/deformities should also be desexed to reduce the spread of thesegenetic diseases to their offspring.

Some examples of proven-heritable or suspect-heritable diseases that we select againstwhen choosing to neuter male cats include: cryptorchidism, polycystic kidney disease (PKD),lysosomal storage diseases and amyloidosis. There are hundreds of others.

4. The prevention or reduction of testicular (and epididymal) diseases:
It is difficult to contract a testicular disease if you have no testicles. Early neutering prevents tomcats from contracting a range testicular diseases and disorders including: testicular cancer,epididymal cancer, orchitis (testicular inflammation with or without infection), epididymitis, testicular torsion, testicular abscessation and testicular trauma.

Note - although testicular and epididymal cancer can occur in the cat and is prevented by castration, itis nowhere near as common for testicular or epididymal cancer to occur in entire tomcats as it is in entire dogs.

5. The prevention or reduction of testosterone-induced diseases:
It is well known that entire dogs can suffer from a range of diseases and medical conditions that are directly associated with high blood testosterone levels. These disease conditions include:benign prostate hyperplasia (BPH), prostatitis, prostatic abscesses, perianal or perineal adenomas (small cancers that occur around the anuses of entire male dogs), perineal hernias and certain castration-responsive skin disorders (dermatoses). Desexing these dogs removes the main source of testosterone from the animal's body (the testes), which not only prevents the onset of these diseases but can even help to control or cure these diseases if they are already present.

Entire cats, on the other hand, very rarely suffer from testosterone-associatedmedical conditions such as prostatitis, BPH, perianal adenoma and perineal herniation. Thus, the prevention of testosterone-associated disease should be considered a very minorreason for male feline desexing. Certainly, the desexing of male cats will most likelyprevent these testosterone-mediated conditions from occurring if the individual cat happens to be prone to them: it's just not very common for these types of diseases to occur in this species. Likewise, if these disease conditions are already present then,like the dog, desexing the cat may go some way towards helping to resolve and treat them.

6. The prevention or reduction of testosterone-mediated behavioural problems:
The testicles are responsible for producing testosterone: the hormone that makes male animals look and act like male animals. It is the testicles that make male catsexhibit the kinds of "male" testosterone-dependent behaviors normally attributed to an entire animal. Entire cats are likely to be more aggressive and more dominant and more prone to male-to-male aggression (inter-male aggression) and fighting than neutered animals are: i.e. they act like bossy entire males. They will tend to exhibit sexualised behaviors including: aroused interestin females of their own species; mounting of females (particularly in-heat, estrus females) andmating of females. They are more prone to displaying unwanted masculine territorial behaviours such as the guarding of resources (food, territory, companion people and so on) and the marking of territory with urine and feces (e.g. entire tomcats will commonly exhibit urine spraying in the house). Additionally, entire male animals are more likely than neutered animals areto leave their yards and roam the countryside looking for females and trouble. Roaming is a troublesome habit because it puts other animals (wildlife and other pets) and humans at risk of harm from your feline pet and it puts the roaming pet at risk from all manner of dangers including: predation by other animals, cruelty by humans, poisoning, envenomation (e.g. snake bite) and motor vehicle strikes. The neutering of entire animals may reduce some of these problematic testosterone-mediated behaviours.

Author's note: Fighting between cats is more common when cats are left entireand undesexed. Owners of fighting cats often spend many hundreds of dollars treating theirpets for fight wounds and cat-fight abscesses. Animals that fight are also more likely tocontract the deadly feline AIDS virus (FIV - feline immunodeficiency virus), which is predominantly spread between tom cats through warring activities (biting and scratching).By reducing the hormonal drive to guard territory and females, desexing reduces the incidenceof fighting and its secondary complications (clawed and lacerated eyes, catfight abscesses, FIV-spread and so on).

7. The reduction of tom cat urine odours:
People with inside cats often have to put up with smelly urine and fecal odours coming fromtheir cats' litter boxes just prior to those feline lavatories being cleaned out. As owners of entire tomcats can attest to, this urine smell can be very pungent andnoxious when it comes out of an intact tomcat, heavy with the stench of male cat pheromones(the odour is the result of testosterone and the retrograde ejaculation of sperm into the bladder). Male cats that have been neutered do not seem to produce as pungent a urine smell asentire toms and, therefore, neutering should be considered a means by which owners of inside cats can seek to reduce litter box urine odors.

Additionally, if the cat in question is a naughty cat that likes to spray inside or toiletin inappropriate areas (beds etc.), reducing the pungency of the urine smell by neuteringwill at least aid you in cleaning up the soiled regions. As an added bonus, neuteringwill sometimes cure inappropriate spraying and toileting behaviour in some tomcats altogether.It is thought that neutering can eliminate urine spraying activities in up to 87% of cats.


2b. The disadvantages of desexing (the cons of desexing) - why some people choose not to neuter cats.

There are many reasons why some individuals, breeders and pet groups choose not to advocatethe sterilization of entire male cats. Many of these reasons have been listed below, however the list is byno means exhaustive.

1. The cat may become overweight or obese:
Studies have shown that neutered animals probably require around 25% fewer caloriesto maintain a healthy bodyweight than entire male animals do. This is because a neutered animalhas a lower metabolic rate than an entire animal does (it therefore needs fewer calories to maintain its bodyweight). Because of this, what tends to happen is that most owners, unaware of this fact, continue to feed their neutered tomcats the same amount of food after the surgery that they did prior to the surgery, with the resultthat their feline pets become fat. Consequently, the myth of automatic post-desexing obesity has become perpetuatedand, as a result, many owners simply will not consider desexing their cats becauseof the fear of them gaining weight and developing weight-related problems (e.g. diabetes mellitus).

Author's note: The fact of the matter is that cats will not become obese simply because they have been desexed. They will only become obese if the post-neutering drop in their metabolic rateis not taken into account and they are fed the same amount of food calories as an entire animal.

Author's note: Those of you who care about your finances might even be able to see the benefits of desexing here. A neutered tom cat potentially costs less to feed than an entire animalof the same weight and, therefore, neutering your animal may well save you moneyin the long run.

2. Desexing equates to a loss of breeding potential and valuable genetics:
There is no denying this. If a dog or cat or horse or other animal is the 'last of its line' (i.e. the last kitten in a long line of pedigree breeding cats), a breeder or pet owner's choice to desex that animal and, therefore, not pass on its valuable breed genetics will essentially spell the end for that breeding lineage.

Author's opinion point: of all the reasons given here that argue against the desexing of male cats, this is probably the only one that has any real merit. Desexing does equate to a loss of breeding potential. In an era where many unscrupulous breedersand pet owners ("backyard breeders" we call them) will breed any low-quality cat regardless ofbreed traits and temperament to make a quick buck, the good genes for breed soundness, breedtraits and good temperament are needed more than ever. Desexing a male cat with good breedcharacteristics, good temperament and no genetically heritable defects/diseases willcount as a loss for that breed's quality in general, particularly if there are a lot of subqualitystuds around saturating the breeding circles.

3. Loss of testosterone as a result of desexing mayresult in immature development of masculine characteristics and a reduced body musculature:
The testicles are responsible for producing testosterone: the hormone that makes male animals look and act like male animals. It is the testicles that make male animalsdevelop the kinds of masculine, testosterone-dependent body characteristics normally attributed to an entire animal. These include: increased muscle size and development; reduced body fat; mature penis development; mature prepuce development (mature penis sheath development); the ability to extrude the penis from the sheath (prepuce) and the suppression of development of feminine characteristics (mammary gland development, milk production etc.). Desexing, particularly early age desexing, may limit the development of mature masculine features such that they remain immature and juvenile looking and cause the neutered animal to have a reduced muscle mass and strength compared to an entire animal of the same size and breeding.

4. Loss of testosterone as a result of desexing mayresult in delayed growth plate closure:
Animals that have been desexed early in life (before the age of 12 months) tend toexhibit delayed closure of their growth plates. Growth plates are the cartilage bands locatedin the ends of the animal's long bones, which are responsible for making the bones grow and elongateduring juvenile bone development and formation. As a result of delayed growth plate closure, desexed animals will often be taller and longer in limb than entire male animals.Whether this increase in growth plate closure time or bone length should be considered a problem or benefit reallydepends on the individual owner, but some people choose not to desex animals early because of it(i.e. there is a concern that these animals may be more prone to orthopedic injuries).

Author's note - Any concerns about the effects of delayed growth plate closure, whilst not normally a problem, can be overcome by desexing after the growth plates have closed.

5. Neutering reduces the male cat's drive to hunt vermin:
Although this phenomenon has yet to be proven, many owners of male mousers (cats kept forthe purpose of keeping rodent numbers low) will refuse to desex them because of the fear that their neutered animals will no longer have any drive to perform the work required of them. This topic is discussed in more detail in section 8b.
Author's note: one could well argue that such a cat might work better if it does not have testosterone-fuelled hormonal urges distracting it from the task at hand.

6. As an elective procedure, desexing costs too much:
The high cost of veterinary services, including desexing, is another reason why somepet owners choose not to get their pets desexed. See section 9 for more on the costs of neutering.

7. The cat will "no longer be a man" without his testicles:
It sounds silly, but it is a very common reason why many owners, especially male owners, will not get their male cats and dogs neutered. See myth 3 (section 8c) for more.



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3. Information about feline neutering age: when to neuter a cat.

The following subsections discuss current desexing age recommendations and how they have been established as well as the pros and cons of early age (8-16 weeks) neutering.

3a. Current desexing age recommendations.

In Australia and throughout much of the world it is currently recommended that male cats beneutered at around 5-7 months of age and older (as far as the "older" goes, the closer to the5-7 months of age mark the better - there is less chance of your cat developing a testosterone-dependant behavioural condition if he is desexed at a younger age).

The reasoning behind this 5-7 month age specification is mostly one of anaesthetic safety for elective procedures.

When asked by owners why it is that a cat needs to wait until 5-7 months of age to be desexed, most veterinarians will simply say that it is much safer for them to wait until this age before undergoing a general anaesthetic procedure. The theoryis that the liver and kidneys of very young animals are much less mature than those of older animals and therefore less capable of tolerating the effects of anaesthetic drugs and less effective at metabolizing them and breaking themdown and excreting them from the body. Younger animals are therefore expected to haveprolonged recovery times and an increased risk of suffering from severe side effects, in particular liver and kidney damage, as a result of general anaesthesia. Consequently, many vets will choose not to anesthetize a young kitten until at least 5 months of age foran elective procedure such as neutering.

The debate:
Whether this 5-7 month age specification for general anaesthesia and desexing is valid nowadays (2008 onwards), however,is much less clear and is currently the subject of debate. The reason for the currentdesexing-age debate is that the 5-7 month age specification was determined ages ago, way back in the days when animal anaesthesia was nowhere near as safe as it is now and relied heavily upon drugs that were more cardiovascularly depressant than modern drugs (e.g. put more strain on the kidneys and liver) and required a fully-functioning, almost-adult liver and kidney to metabolize and excrete them from the body. Because modern animal anaesthetic drugs are so much safer on young animals than the old drugs used to be, there is increasing push to drop the age of desexing in veterinary practices. This puts us onto the topic of early age neutering (see next section - 3b).

Are there any disadvantages to desexing at the normal time of 5-7 months of age?
Just as there are disadvantages of desexing an animal at a very young age (see section 3b), thereare also some disadvantages associated with desexing at the usually-stated age of 5-7 months:

  • Some people find it inconvenient to wait until 5-7 months of age to desex.
  • There is a chance that an early-maturing tom may be able to mate and sire unwanted kittens before this age, adding to the number of unwanted litters destroyed and dumped.
  • For people who choose to have their pets microchipped during anaesthesia, there is an inconvenient wait of 5-7 months before this can be done. If the animal gets lost prior to this age, the unchipped cat may fail to find its way home.
  • Many of the behavioural issues commonly associated with entire male animals may become manifest before the time of the desexing age recommendations (e.g. urine spraying, fighting). These behavioural problems, once established, may persist and remain problematic even after the animal is sterilized.


Author's note on points made above: According to references used to research this web page,it is considered unusual for male cats to produce viable sperm and therefore impregnatefemales before the age of 30-36 weeks (i.e. 7 months on). Full sexual maturity in tomcatsis usually achieved at around 18 months to 2 years of age. It is also uncommon for toms to start urine spraying andfighting for females and hierarchy before the age of 12 months (usually 18 months to 2 years).


3b. Neutering kittens - information about the early spay and neuter of young cats (kitten desexing).

We kittens can be desexed at 8-12 weeks. Then we will be ready to find homes!As modern pet anesthetics have become a lot safer, with fewer side effects, thedebate about the recommended age of feline neutering has been reopened in the veterinary worldwith some vets now allowing their clients to opt for an early-age spay or neuter, provided theyappreciate that there are greater, albeit minimal, anaesthetic risks to the very young pet when compared to themore mature pet. In these situations, cat and dog owners can now opt to have their male and femalepets desexed as young as 8-9 weeks of age (the vet chooses anaesthetic drugs that are not as cardiovascularly depressant and which do not rely as heavily upon extensive liver and kidney metabolism and excretion).

Powerful supporters of early spay and neuter - in 1993, the AVMA (American Veterinary Medical Association) advised thatit supported the early spay and neuter of young dogs and cats, recommending that puppiesand kittens be spayed or neutered as early as 8-16 weeks of age.

IMPORTANT - because of the rising problems of pet and feral animal overpopulation,it is now the law in many states (e.g. Canberra, Australian Capital Territory) for kittensto be desexed prior to 12 weeks of age. What this means is that early age desexing is now compulsory, regardless of any (minor) anaesthetic risks to the animal, andveterinarians who advise desexing at 5 months of age onward are breaking the law. Owners ofcats (and dogs) need to check their local state laws on pet neutering ages.


The advantages of the early spay and neuter of young cats:
Certainly, there are some obvious advantages to choosing to desex an animal earlier ratherthan later. These include the following:

  • People do not have to wait 5-7 months to desex their pets. The procedure can be over and done with earlier.
  • Tom cats neutered very early will not attain sexual maturity and will therefore be unable to sire any kittens of their own. This role in feline population control is why most shelters choose to neuter early.
  • It makes it possible for young kittens (6-12 weeks old) to be sold by breeders and pet-shops already desexed. This again helps to reduce the incidence of irresponsible breeding - cats sold already desexed cannot reproduce.
  • For owners who choose to get their pets microchipped during anaesthesia, there is no inconvenient wait of 5-7 months before this can be done.
  • Some of the behavioural problems and concerns commonly associated with entire male animals may be prevented altogether if the kitten is desexed well before achieving sexual maturity (e.g. urine spraying, marking territory, fighting for territory).
  • From a veterinary anaesthesia and surgery perspective, the duration of surgery and anaesthesia is much shorter for a smaller, younger animal than it is for a fully grown, mature animal. I take about 1 minute to neuter a male kitten of about 9 weeks of age compared to about 3-5 minutes maximum for an older tom.
  • The post-anaesthetic recovery time is quicker and there is less bleeding associated with an early spay or neuter procedure.

  • From a veterinary business perspective, the shorter duration of surgery and anaesthesia time is good for business. More early age neuters can be performed in a day than mature cat neuters and less anaesthetic is used on each individual, thereby saving the practice money per procedure.
  • Routine, across-the-board, early spay and neuter by shelters avoids the need for a sterilization contract to be signed between the shelter and the prospective pet owner. A sterilization contract is a legal document signed by people who adopt young, non-desexed puppies and kittens, which declares that they will return to the shelter to have that dog or cat desexed when it has reached the recommended sterilisation age of 5-7 months. The problem with these sterilisation contracts is that, very often, people do not obey them (particularly if the animal seems to be "purebred"); they are rarely enforced by law and, consequently, the adopted animal is left undesexed and able to breed and the cycle of pet reproduction and dumped litters continues.



The disadvantages associated with the early spay and neuter of young kittens:
There are also several disadvantages to choosing to desex an animal earlier ratherthan later. Many of these disadvantages were outlined in the previous section (3a)when the reasons for establishing the 5-7 month desexing age were discussed and include:

  • Early age anaesthesia and desexing is never going to be as safe as performing the procedure on an older and more mature cat. Regardless of how safe modern anaestheticshave become, the liver and kidneys of younger animals are considered to be less mature than those of older animals and therefore less capable of toleratingthe effects of anaesthetic drugs and less effective at metabolizing them and breaking themdown and excreting them from the body. Even though it is very uncommon, there will always be the occasional early age animal that suffers from potentially life-threateningside effects, in particular liver and kidney damage, as a result of young age anaesthesia.
  • There is an increased risk of severe hypothermia (cold body temperatures) and hypoglycemia (low blood sugar) occurring when young animals are anesthetized. This hypothermia predisposition is caused by the young animal's increased body surface area (higher area for heat to be lost), reduced ability to shiver and reduced body fat covering (fat insulates against heat loss). The predisposition towards hypoglycemia is the result of a reduced ability to produce glucose from stores of glycogen and body fat as well as the fact that these stores of fat and glycogen are smaller in the young animal.

  • Loss of testosterone production at a very early age, as a result of desexing, mayresult in extremely immature development of masculine characteristics and a significantly reduced body musculature. Note - no significant difference was found in the development of masculine features and body musculature between catsdesexed at 7 weeks and those desexed at 7 months, however.
  • Early neutering may result in retained juvenile behaviours inappropriate to the animal's age later on.

  • Early age neutering prevents cat breeders from being able to accurately determine which kittens will be valuable stud animals (it is too early to tell when they are only kittens). Because desexing equates to a loss of breeding potential and valuable genetics, many breeders choose to only desex their cats after they have had some time to grow (after all, it is not possible to look at a tiny kitten and determine whether or not it will have the right color, conformation and temperament traits to be a breeding and showing cat). This allows the breeder time to determine whether or not the animal in question will be a valuable stud animal or not.
  • Kittens neutered very early will be completely unable to extrude their penises from their preputial sheaths throughout life. This can potentially result in urinary hygiene problems and an increased risk of preputial urine scalding and prepuce infections throughout life.
  • Early spaying and neutering will not 100% reduce pet overpopulation and dumping problems when a large proportion of dumped animals are not merely unwanted litters, but purpose-bought, older pets that owners have grown tired of, can't manage, can't train and so on. Those people, having divested themselves of a problem pet, then go and buy a new animal, thereby keeping the breeders of dogs and cats in good business and promoting the ongoing over-breeding of animals.



Author's note: at the time of this writing, I was working as a veterinarian in a highoutput animal shelter in Australia. Because shelter policy was not to add tothe numbers of litters being born irresponsibly by selling entire animals, all cats, including kittens, were required to be desexed prior to sale. Consequently, it was not unusual for us to desex male and female puppies and kittens at early ages (anywhere from 8 weeks of age upwards). Hundreds of puppies and kittens passed under the surgeon's knife every year on their way to good homesand I must say that the incidence of post-operative complications that were a directresult of underage neutering was exceedingly low.


For a nice visual guide to early age kitten neutering surgery at our shelter, visit our pictorialearly age male kitten neutering surgery page.




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4. Neutering procedure (desexing surgery) - a step by step pictorial guide to feline neuter procedure.

As stated in the opening section, neutering is the surgical removal of a male cat's testicles. During the procedure, each of the tomcat's testes and testicular epididymi are removed along with sections of the cat's testicular blood vessels and spermatic ducts (vas deferens or ductus deferens).And to be quite honest, from a general, non-veterinary pet owner's perspective, this is probably all of the informationthat you really need to know about the surgical process of desexing a tom cat.



Desexing basically converts this ...

This is an image of a feline scrotum prior to desexing surgery.
Image: This is a preoperative picture of a feline scrotum containing two round testicles.



... into this ...

This is a photo taken of a cat's scrotum (scrotal sac) immediately following desexing surgery (neutering). The scrotum has no testes and is flattened.
Image: This is a photo of the same cat's scrotal sac after the testicles have been removedat surgery. They are still a little swollen from surgery, which makes them appear fullerthan they actually are, however there are no testicles inside.



... by removing both of these.

This is a picture of two feline testicles that have been removed by neutering (desexing) surgery.
Image: This is a picture of two feline testicles that have been removed by sterilisation surgery.You can clearly see the testis and epididymus of each testicle: these are the main sites of testosterone production and sperm production and sperm maturation in the male animal.


For those of you readers just dying to know how it is all done, the following section is a step by stepguide to the surgical process of desexing a cat. There are numerous surgical desexing techniques available for use by veterinarians, however, I have chosen to demonstrate the very commonly-used "scrotal incision procedure" of feline castration. Both diagrammatical and photographic images are provided to illustrate the process.

NEUTERING PROCEDURE STEP 1: Preparation of the animal prior to entering the veterinary clinic.

Some basic steps on preparing and fasting your pet for surgery.Preparation of an animal for any surgical procedure begins in the home.

Your animal shouldbe fasted (not fed any food) the night before a surgery so that he has no food in his stomachon the day of surgery. This is important because cats that receive a general anaestheticmay vomit if they have a full stomach of food and this could lead to potentially fatal complications. The cat could choke on the vomited food particles or inhale them into its lungs resultingin severe bronchoconstriction (a reaction of the airways towards irritant food particles, common in cats,which results in them spasming and narrowing down in size such that the animal can not breathe)and even bacterial or chemical pneumonia (severe fluid and infection build-up within the air spaces of the lungs).

The cat should be fed a small meal the night before surgery (e.g. 6-8pm at night) and then not fed after this. Any food that the animal fails to consume by bedtime should be takenaway to prevent it from snacking throughout the night.

Young puppies and kittens (8-16 weeks) should not be fasted for more than 8 hours prior to surgery.

Water should not be withheld - it is fine for your feline pet to drink water before admission into the vet clinic.

Please note that certain animal species should not be fasted prior to surgery or, if theyare fasted, not fasted for very long. For example, rabbits and guinea pigs are notgenerally fasted prior to surgery because they run the risk of potentially fatal intestinal paralysis (gut immotility) from the combined effects of not eating and receiving anaesthetic drugs. Ferrets have a rapid intestinal transit time (the time taken for food to go from the stomach to the colon)and are generally fasted for only 4 hours prior to surgery.

If you are going to want to bath your tomcat, do this before the surgery because you willnot be able to bath him for 2 weeks immediately after the surgery (we don't want the healing neutering wounds to get wet).Your vet will also thank you for giving him a nice clean animal to operate on.



NEUTER PROCEDURE STEP 2: The animal is admitted into the vet clinic.
When an animal is admitted into a veterinary clinic for desexing surgery, a number of things will happen:

  • 1) You should arrive at the vet clinic with your fasted cat in the morning. Vet clinics usually tell owners what time they should bring their pet in for surgical admission and it is important that you abide by these admission times and not be late. If you are going to be late, do at least ring your vet to let him know. Vet clinics need to plan their day around which pets arrive and do not arrive for surgery in the morning. A pet turning up late throws all of the day's planning out the window. Do remember that your vet has the right to refuse to admit your pet for surgery if you arrive late.
  • 2) The animal will be examined by a veterinarian to ensure that he is healthy for surgery. His gum color will be assessed, his heart and chest listened to and his temperature taken to ensure that he is fine to operate on. Some clinics will even take your pet's blood pressure. This pre-surgical examination is especially important if your pet is old (greater than 7-8 years).
  • 3) You will be given the option of having a pre-anaesthetic blood panel done. This is a simple blood test that is often performed in-house by your vet to assess your cat's basic liver and kidney function. It may help your vet to detect underlying liver or kidney disease that might make it unsafe for your cat to have an anaesthetic procedure. Better to know that there is a problem before the pet has an anaesthetic than during one! Old cats in particular should have a pre-anaesthetic blood panel performed (many clinics insist upon it), but cautious owners can elect to have young pets tested too.
  • 4) The dangers and risks of having a general anaesthetic procedure will be explained to you. Please remember that even though neutering is a "routine" surgery for most vet clinics, animals can still die from surgical and/or anaesthetic complications. Animals can have sudden, fatal allergic reactions to the drugs used by the vet; they can have an underlying disease that no-one is aware of, which makes them unsafe to operate on; they can vomit whilst under anaesthesia and choke and so on. Things happen (very rarely, but they do) and you need to be aware of this before signing an anaesthetic consent form.
  • 5) You will be given a quote for the surgery.
  • 6) You will be asked to sign an anaesthetic consent form. As with human medicine, it is becoming more and more common these days for pet owners to sue vets for alleged malpractice. Vets today require clients to sign a consent form before any anaesthetic procedure is performed so that owners can not come back to them and say that they were not informed of the risks of anaesthesia, should there be an adverse event.
  • 7) Make sure that you provide accurate contact details and leave your mobile phone on so that your vet can get in contact with you during the day! Vets may need to call owners if a complication occurs, if an extra procedure needs to be performed on the pet or if the pet has to stay in overnight.
  • 8) Your cat will be admitted into surgery and you will be given a time to return and pick it up. It is often best if you ring the veterinary clinic before picking your pet up just in case it can not go home at the time expected (e.g. if surgery ran late).


NEUTER PROCEDURE STEP 3: The animal will receive a sedative premedication drug (premed) and, once sedated, it will be given a general anaesthetic and clipped and scrubbed for surgery.
A tom cat's testicles being scrubbed and cleaned before a neuter procedure.The cat is normally given a premedication drug beforesurgery, which is designed to fulfill many purposes. The sedative calms the feline makingit slip into anaesthesia more peacefully; the sedative often contains a pain reliefdrug (analgesic), which reduces pain during and after surgery and the sedative action resultsin lower amounts of anaesthetic drug being needed to keep the animal asleep. Dependingupon the drug cocktail given, other specific effects may also be achieved including:reduction of saliva production and airway secretions (this reduces drooling and therisk that saliva and respiratory secretions may be inhaled into the lungs during surgery);improved blood pressure; airway dilation (making it easier to breathe) and so on.

General anaesthesia is normally achieved by giving the cat an intravenous injection ofan anaesthetic drug, which is then followed up with and maintained using the same injectabledrug or even an anaesthetic inhalational gas. The animal has a tube inserted down its throat during the surgery to help it breathe better; to stop it inhaling any saliva or vomitus and to facilitate the administration of any anaesthetic gases.

The skin over the animal's groin and scrotum is shaved andscrubbed with antiseptic solution prior to surgery.



The surgery:
In order for you to properly understand the process of tom cat neutering surgery, I have to take a second to explain the anatomy of the male cat's reproductive structures (testicles, penis and so on).

A diagram of the reproductive anatomy of an entire male cat (tomcat). You need to know this in order to neuter a male feline.
Image: This image is a diagram of the reproductive anatomy of an entire male tomcat. The animalis drawn laying on its back as it would be positioned during a sterilization surgery. On the diagram, I have indicated the following structures: testicles (pink) contained within the animal's scrotalsac; bladder and urethral outflow tract (yellow); kidneys (brown); ureters (mauve);abdominal wall muscles (marked in dark red); vas deferens or ductus deferens (white); testicular blood vessels (red) and other male reproductive structures, such as the prostate gland, marked in orange. Notice how the ureter of the kidney loops around the vas deferens (spermatic duct) of the testicle - this occurs during early foetal life when the testicle descends from the kitten's abdominal cavity and into the scrotal sac.


The reproductive anatomy of an entire male cat. You need to know this in order to perform feline neutering surgery.

Image: This diagram is a close-up view of the image contained above and is designed tohighlight certain anatomical structures that are important considerations in this cat neutering surgery.

The first thing to notice is that each testicle is contained within a large pouch of skin located just behind (caudal to) and slightly lateral to (alongside) the animal's penis. This pouch of skin is called the scrotum or scrotal sac. This is where the cat's testicles will be taken from.

The second thing to notice is thatthe spermatic ducts (vas deferens) and blood vessels supplying each of the testicles arise from within the animal's abdominal cavity. These vessels exit the animal's abdominal cavityin the region of the animal's groin, via a natural hole in each side (right and left) of the abdominal wall called the inguinal canal or inguinal ring (marked in pale purple). After exiting the abdominal cavity via the inguinal canal, these ducts and vessels run deep within the fat situated alongside the animal's penis and into the scrotum, where they unitewith the sperm ducts and blood vessels within the animal's testicles.

The third thing to remember is that some of the thick connective tissue lining the animal's abdominal cavity (the peritoneal lining - marked in green) actually comes out through the inguinal canal when the testicle descendsduring infancy and encases the testicle within the scrotal sac. The section of peritoneal liningcontaining the testicle within the scrotal sac and inguinal canal is termed the tunicavaginalis or vaginal tunic. On top of this, some of the abdominal fluid (lubricating fluidthat exists in small amounts within the abdomen to let the organs slide over each other and not adhere to each other) and abdominal 'space' that exists within the abdominalcavity also goes with the peritoneal outpouching (tunica vaginalis) and into the scrotal sac andinguinal canal surrounding the testicular structures. This abdominal fluid and 'space' is markedin pale blue. It allows the testicular vessels and testicles to slide a bit withinthe scrotal sac and tunica vaginalis casing.



FELINE NEUTERING PROCEDURE STEP 4: The scrotal skin is incised over each testicle.

This diagram image indicates where the first incision is made during cat desexing surgery. The skin and tunica vaginalis (green) are cut.This is an image of a cat scrotum showing where the two scrotal incisions are made during feline neutering surgery.
Images: An incision is made into the scrotal skin just over each of the cat's testicles. Thisincision passes through the cat's skin and through the tunica vaginalis layer (marked in green).Each testicle will be removed through a separate scrotal incision.

Caution needs to be taken to ensure that the urethra or penis is not accidentally cut into during this incision.



NEUTER PROCEDURE STEP 5: The testicle is elevated through the hole in the skin.

The first feline testis is pulled out through the hole in the scrotal skin.
Image: The first testicle is pulled out through the hole in the animal's skinand tunica vaginalis (vaginal tunic). Because the space between the tunica vaginalis and testicle contains smallvolumes of lubricating fluid (blue) from inside of the cat's abdominal cavity, the testicledoes not stick to the tunica vaginalis capsule but instead slips easily out of it.




NEUTER PROCEDURE STEP 6: The vas deferens (ductus deferens or spermatic duct) is separated away from the testicle and testicular blood supply.

The vas deferens (ductus deferens or spermatic duct) is separated away from the testicle and testicular blood supply during feline neutering.
Image: The vas deferens (also called the spermatic duct or deferent duct) and epididymal structuresare separated away from the testis and testicular blood supply. This creates two separate "strings"which can be tied around each other: as indicated in the next step.



NEUTERING PROCEDURE STEP 7: The testicular blood vessels and spermatic ducts are knotted around each other to occlude the testicular blood supply.

The blood vessels are tied closed by knotting the blood vessels around the spermatic duct. This allows the testicle to be removed without bleeding.
Image: The testicular blood vessels and spermatic cords are knotted tightly around each otherrepeatedly in order to occlude (block) the blood vessels supplying the feline testicles. This prevents the animal's testicular blood vessels from bleeding once the testicle is cut off. It also prevents the veterinarian from having to place any sutures.



NEUTERING PROCEDURE STEP 8: The testicle is removed.

The testicle is removed during feline neutering surgery.
The surgeon cuts off the testicle (testis and epididymus) above the level of the knotsand discards it. The first testicle has been removed.



NEUTERING PROCEDURE STEP 9: Steps 5-8 are repeated for the opposite testicle.



NEUTERING PROCEDURE STEP 10: The subcutaneous fat layers and skin are not sutured closed (stitched shut).

The skin wounds are not closed using any sutures (stitches). These tiny castration wounds tend to heal up fine without suturing and thus there are no sutures that requireremoval later on.




Early age kitten neutering:
Kittens can be neutered using the neutering procedure described above. For kittens under1 kilogram in weight, a simpler, faster method of feline castration can also be used. Visit our pictorialguide to early age male kitten neutering surgery.

A note on cryptorchidism (undescended testicles):
If your cat has cryptorchidism or retained testicles, a different surgical proceduremay be indicated. Please see our excellent cryptorchidism page for more details.




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5. Cat neutering after-care - what you need to know about caring for your cat after neutering surgery.

When your cat goes home after neutering surgery, there are some basic exercise, feeding,bathing, pain relief and wound care considerations that should be taken into account to improve yourpet's healing, health and comfort levels.

1) Feeding your cat immediately after feline neutering surgery:
After a cat or kitten has been desexed, it is not normally necessary for you to implement anyspecial dietary changes. You can generally go on feeding your pet what it has always eaten. Some owners like to feed their pet on bland diets (e.g. boiled, fat-free, skinless chickenor a commercial prescription intestinal diet such as Hills feline i/d)for a few days after surgery in case the surgery and anaesthesia process has upset their tummies. This is not normallyrequired, but is perfectly fine to do.

Unless your veterinarian says otherwise, it is normally fine to feed your cat the night aftersurgery. Offer your pet a smaller meal than normal in case your pet has an upset tummyfrom surgery and do not be worried if your pet won't eat the night after surgery.It is not uncommon for pets to be sore and sorry after surgery and to refuse to eat that evening.

If your cat is a bit sooky and won't eat because of surgery-site pain, feel freeto tempt him with tasty, strong-smelling foods to get him to eat. Skin-free roast chickenoften works well and is not too heavy on the stomach. Many cats also like strong-smellingfishy foods like fish-containing tinned food, tinned tuna or salmon or cooked fish filletsand small prawns. Avoid fatty foods such as mince, lamband processed meats (salami, sausages, bacon) because these will cause digestive upsets.

Be aware of your pet's medications and whether they need to be given with food. Some catsgo home on non-steroidal anti-inflammatory drugs (NSAIDs) such as Carprofen(tradenames include: Prolet, Rimadyl, Carprofen tablets) and Meloxicam (tradenames include Metacam). These drugs need to be given with food. Do not give these drugs if your cat is refusing to eat.

Most cats that are neutered are not normally off their food for more than a day. You should contact your vet if your pet does not eat for more than 24 hours after surgery.


2) Exercising your cat after neutering:
It takes 7-14 days for castration wounds to heal after surgery. It is thereforerecommended that running-around exercise be avoided or minimised during this periodto allow the skin the best chance of staying still and healing.

Of course, many of you scoff at the idea of "keeping a cat or kitten rested and still!" It is, therefore, normally fine if your cat romps around inside your house and performs its normal indoor activities and play. I would, however, avoid letting your catgo outside until he has had time to heal (7 days minimum). This will prevent excessive exercise, which couldimpede healing, and it will also prevent the open feline neutering wounds from becomingpacked with mud and dirt.


3) Wound care after feline neutering surgery:
Normally you do not have to do anything special with your pet's surgical desexing wounds (e.g washingand bathing them) after surgery. The most important thing that you do need to do is monitor the wounds to ensure thatthey remain looking healthy and clean.

Check the scrotum daily. Look out for any signs of excessive redness, swelling and wound pain(surgical wounds should not normally appear painful or red beyond the first 3-5 days after surgery). Look out for obvious signs of infection (e.g. a yellow or green pussy discharge) or signsthat the wounds are breaking down (the wounds will split and contain cottage-cheese-like white or yellownecrotic tissue inside them if they are breaking down). If you see any of these signs, take the pet toyour vet for a check up.

If the wound site gets dirty (e.g. covered in mud or feces), you can clean the wounds withwarm salty water, saline (0.9% NaCl) or a very dilute betadine solution (betadine solution in watermade up to a weak-tea colour concentration) to remove the contamination. The scrotum and wound sites should then be dried thoroughly to stop bacteria from wicking deep into the surgical site. The cleaned wounds should then be closely monitored over the next few days because wounds soiledin dirt or faeces are at high risk of becoming infected, even if they are bathed.



Do not let your pet lick its neutering wounds! This is a major cause of surgery wound breakdown - the pet licksthe wounds and introduces mouth-bacteria into the wounds making them wet and infectedand unable to heal.

At the very first sign of wound licking, go to your vet immediately and get anElizabethan collar (E collar) for the cat. The collar will stop the cat tampering withthe wounds and hopefully prevent wound break down and infection. If the cat starts lickingin the middle of the night and you can not get an E collar, you can cut the circular bottom out of an appropriately-sized, clean plastic flower pot (leave the drainage holes intact);place this over your pet's head and neck like an Elizabethan collar and thread the pet'scollar or a stocking through the pot-plant drainage holes to secure it to your pet's neck. Be careful to place it so that your pet can not choke and go and get a proper E collarfrom your vet in the morning.

Wound licking can also be reduced by putting bitter apple spray, methyl phthalate solutionor another commercial bitterant solution onto the pet's suture line. Wound-Gard is onecommercial product that serves this role (there are many other products that serve asimilar function).


4) Bathing or washing your cat after cat neutering:
Because it takes 7-14 days for skin wounds to heal and seal closed, it is advisedthat the animal not be bathed or allowed to go swimming for the first 14 days after surgery. Wetting the wounds before this time may allow bacteria to enter the surgery site andset up an infection, which could result in wound breakdown and abscessation.


5) Pain relief after neutering:
In my experience, most tomcats do not seem to show all that much pain after neutering surgery. Many start playing and running around the very same night! If your pet is in pain, however,there are ways that you can help.

Go to your vet for some analgesic pills or drops. Most vets send their neutering patientshome with a few days of pain relief as a matter of course, however, some vet clinics do not.If you haven't been sent home with any pain relief for your pet and your pet shows signs ofpain after surgery, you can return to your vet clinic and request pain relief pills.If your pet is very old or it has compromised kidney or liver function, certain painmedications may not be recommended and other pain relief solutions may need to be found.

DO NOT self-medicate your pet with human pain-killers. Many human pain relief drugs aretoxic to cats. In particular, never give a cat panadol or paracetamol (also called acetaminophen)!

Keep your cat confined and quiet and indoors. Pets that are allowed to run around after surgeryare more likely to traumatize and move their wounds, leading to swelling andpain of the surgical site. Reducing activity means less pain.


6) Monitor your cat's general demeanor and well-being after neutering:
Your cat should be back to normal within 1-3 days after surgery. He should beeating, drinking, urinating, defecating and wanting to play and interact just as muchas he did prior to the surgery. If your pet is depressed; not eating; not drinking; drinking excessively; not defecating; defecating black, tarry stools; not urinatingand/or shows any signs of vomiting a few days after surgery, this is not normal. You needto take your pet to a vet clinic immediately.



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6. Possible surgical and post-surgical complications of neutering cats.

There are some surgical and post surgical complications of desexing a cat thatshould be considered before you take the step of having your pet neutered. These are outlinedbelow. The most important thing to remember about the complications listed below is that the vast majority of these complications are very rare and the small risk of themoccurring should not outweigh the benefits of having your pet neutered. Of those complicationsthat are more common (the common ones are indicated), the vast majority of these arenot life-threatening and most can be prevented by good attention to after-care and wound care.


6a. Pain after surgery (common).
It is not uncommon for cats to show some signs of mild to moderate discomfort and painimmediately after having a desexing surgery. It stands to reason: the vet has just performeda surgical procedure on a very delicate area of the male body.

Cats that are in discomfort after desexing will normally show signs and symptoms suggestiveof pain in the groin region. The animal may pant; refuse to settle; adopt a stiff hind leg gait (these animals are reluctant to move their hind legs much when walking) and refuse to sit down in a normal sitting posture. Some cats will tremble and shiver.It is not uncommon for painful cats to hide under beds and seek solitude in dark places and want to be alone. They will often growl and hiss aggressively and may even swipe with their claws andbite when touched and handled by their owners. Some cats will be irritated by the incision wounds and/or by the fact that the delicate scrotal skin was shaved (and thus abraded a little) and keep licking the region obsessively (this licking needs to be discouraged by placing an Elizabethan Collar on the cat or a bitterant on the wound - see section 5 on aftercare). Some cats will even go off their food a bit for a few daysafter desexing because of the discomfort.

If your pet is in pain, you can return to your veterinary clinic for some analgesic (pain killer) pills. Most vets send their neutering patients home with a few days of pain relief as a matter of course, however, some vet clinics do not. If you haven't been sent home with any pain relief for your cat and your pet shows signs ofpain after surgery, you can return to your vet clinic and request pain relief pills - thesewill normally be enough to keep your pet comfortable. If your pet is very old or it has compromised kidney or liver function, certain painmedications may not be recommended and other pain relief solutions may need to be found.

Keep your pet confined and quiet and indoors if it is in pain. Pets that are allowed to run around after surgeryare more likely to traumatise and move their wounds, leading to swelling andpain of the surgical site. Reducing activity means less pain. Keeping the catindoors will also allow you to keep an eye on it, as painful cats allowed outsidewill often take refuge in dark, quiet places (e.g. under the house) and not come out for a few days (which canbe very worrying for the owner).

If the scrotal skin appears very abraded and red to you (either from clipper rash during pre-surgicalshaving of fur or due to your pet's licking), you should speak to your vet about it. He may prescribe some cream containing a steroidal anti-inflammatory drug, an antibioticcompound and a local anaesthetic (e.g. tradenames include Ilium Neocort Cream, Neotopic Cream)to apply to the abraded regions to soothe them. Do not apply the cream directly to the surgical wounds.

If your cat's discomfort lasts more than about 1-3 days after surgery, you should seek advice from your vet. Most pets don't show signs of surgical discomfort beyondabout 3 days and pain persisting beyond this point may be a sign of wound infectionor some other issue.

IMPORTANT SAFETY TIP - be very careful when handling sore cats immediately after surgery. Even the nicest cat will scratch and bite if you handle it in a painful region. If thecat starts lunging, growling, snorting or hissing, keep away.


6b. Swollen, bruised, blood-filled scrotum after desexing (common).
It is not uncommon for cats to go home from sterilisation surgery with a very swollen, bruised-looking, blood-filled scrotum.

The condition is more commonly seen in large male cats that have been neutered as adults later in life(basically, these animals have larger blood vessels in their scrotal pouches and vaginal tunics,which are more prone to heavy bleeding when incised). From a post-operative perspective, bleeding into and swelling of the scrotal sac may also occur if a cat is allowed to run around too much (excessive exercise and rough-and-tumble)or lick its surgery site excessively in the hours to days after surgery.

Rarely, a blood filled scrotal sac may be an indication that the animal in question hasa bleeding disorder, which needs to be worked up. It is not uncommon for vets to diagnosea medical blood clotting condition such as rodenticide poisoning (rat bait poisoning), platelet deficiency, hemophilia and so on by accident during surgery because the animal wouldn't stop bleeding during surgery or the scrotal sac fills with blood afterwards.

When hemorrhage into the scrotal sac occurs, the signs are normally pretty evident. The animal will develop a swollen, enlarged scrotal sac, which may appear very red andbruised-looking in appearance. Some owners even ring their vet accusing him or her ofnot desexing their cat because the large, blood-swollen scrotum sac looks the same sizeas it did when it contained testes. Animals with swollen testicle sacs will often exhibit signs ofpain: they may pant; pace the room (not want to settle); walk stiffly with their hind legs and refuse to sit down in a normal sitting posture. Some will isolate themselvesand hide in dark places and some will show aggression when handled. Many catswill lick the swollen region obsessively, which only increases the scrotal trauma andswelling.

Generally, blood-filled, swollen scrotal sacs will resolve and shrink on their ownas the blood is reabsorbed back into the cat's body. They do not normally require any specific treatment.You can manage the animal's discomfort by giving it feline pain killers, restrictingexercise and preventing licking.


6c. Desexing wound infections (not very common at male feline neutering sites).
Wound infection occurs when bacterial organisms gain access to the surgical incision site/s and multiply there in large numbers. This bacterial invasion causes damage to the body tissues at the site of infection (this limits the healing of tissues in the region) and triggers a secondary immune system attack on the infected region, resulting in inflammation (redness, swelling, heat)and a build up of pus (invading white blood cells produce yellow or green discharges) in the area.

Owners often first notice infection when the neutering incision lines become sore, swollen, redand hot-to-touch. Sometimes, the pet will even tell the owner that it is in pain by licking theinfected regions obsessively: infection should certainly be suspected if a pet goes from initiallynot being bothered by its wounds to licking and biting at them excessively. Within hours to days of this redness and inflammation being noticed, the owner may witness a yellow to green purulent discharge (pus) coming from the incision line or lines. Sometimes, if the skin incision site has sealed over but the infection has gained access to the deeper scrotaltissues, pus and infection will build up underneath the skin producing a painfulpus-filled swelling called an abscess. When the abscess bursts, large amounts ofpus will drain out of the area.

Wound infection is pretty uncommon in most routine desexing surgeries and most commonly occurs because of poor home care. It tends to occur because the pet was allowed to lick the surgical wounds and, consequently, introduce mouth bacteria into the surgical incisionline/s. Infection also tends to occur if the open, unhealed wounds are allowed to get wet (e.g. the animal was bathed, allowed to go swimming, allowed to lay in mud) or if the wounds are allowed to become soiled by faeces, urine or dirt. Because the testiclesof the cat are located just beneath its anus, there is a higher risk of feces and fecalbacteria contaminating and infecting the surgical neutering wounds (a risk that is greatly increasedif the cat has diarrhea - runny, watery faeces). Wound infection may also occur if the vet performs the surgery on an animal with diseased allergic or infected scrotal/groin skin. Bacterialnumbers are very high in diseased, infected skin and will easily enter the wound site during surgery, regardless of the amount of pre-surgical prepping done.

Very occasionally, castration wound infection may be the result of poor surgical technique (e.g. vets not wearing gloves to do surgery); poor skin preparation before surgery; a freak bug entering the surgical site(sometimes nasty bacteria like Golden Staph and flesh-eating Streptococcus and Mycobacteria species will find their way into a vet clinic and cause havoc) or the animal having a poor or compromised immune system. Animals with Cushing's disease, Diabetes Mellitus, FIV, FeLV andother immune system suppressive disorders may be more prone to wound infections.

Wound infection is definitely cause to see your vet. If the wound infection is only mild or early, the tomcat may only require antibiotic coverage; an Elizabethan collar and better home care to treat the problem. If the wound has completely abscessated and is at risk of falling apart, the vet may need to operate on your cat again to retrim and repair and clean the surgical wound. Healing will then take anotherfull 10-14 days to occur.


6d. Penis and/or urethra laceration (very rare).
The cat's testicles and penis are located close together.As you can see from the image opposite, the penis and testicles (scrotum) of theentire male cat are located very close to each other anatomically. It is, therefore, theoretically possible (very rare) for a careless or inexperienced veterinarysurgeon to slice into the animal's penis and/or urethra if he or she cuts too deeplyor in the wrong location during feline neutering surgery.

If this occurred, a very severe, costly and potentially life-threateningsituation would result.

If the cat's penis was cut, the animal would suffer from extreme penile bruising andhemorrhage (the penis is extremely vascular, with massive blood chambers and blood vessels inside of itsfleshy wall). Bleeding could be so severe that the cat might even require a bloodtransfusion and intravenous fluid support to save its life. It is also possible that the animalcould lose the end of its penis as a result of a loss of blood supplyto the end of the penis. Reconstructive surgery would then be required toremove the necrotic (dead) penis and refashion it so that the animal was able to pass urine.A complete perineal urethrostomy surgery (a surgical procedure that essentially removes a male cat's penisand converts it into a more feminine-looking vulva-like opening) might even be required.

Rupture of the urethra would result in all of the severe bleeding and other potentialcomplications described above for penis laceration because the penis would have to becut in order for the urethra to be lacerated (the urethra runs inside of the penis and can not be cutwithout the penis also being cut). The cat would suffer bleeding into the urethral tract(it would urinate blood-filled urine). If urethral repair was not carried outpromptly and correctly, urine would start to leak from the torn urethra into the fat and skin of the surgical site. This urine is very acidic and irritant and leakage of urine under the skin would result in severe tissue swelling, pain and inflammation. It is very likely that much of the fat and tissuesexposed to the urine would break down and rot along with the skin incision site itself, resulting in a nasty, open surgical neutering wound through which urine and inflammatory fluids would ooze. Such an animal would be expected to be very unwell (may need 24 hour care)and very painful. Laceration of the urethra would require urgent surgical repair and there isa high risk that the animal might develop urethral strictures (scarring and narrowing ofthe urine outflow passage) down the track.


6e. Excessive wound hemorrhage - excessive bleeding during or after cat neuter surgery (rare).
A small amount of bleeding from the feline neutering wounds is normal. Open incision lines will ooze small amounts of blood.It is very uncommon to see a pet cat bleed excessively from its incision site/s followinga feline neutering surgery. Neutering sites sometimes ooze a bit of bloody fluid (an occasional drop here and there) a hour or so after surgery (see picture opposite), but they do not normally pour blood.

Excessive bleeding of feline neutering sites may be a sign that the veterinarian has not performed the desexing surgery properly (e.g. the vet has lacerated the cat's penis or a major blood vessel or not tied off one of the testicular blood vessel stumps properly), however, in these kinds of situations, the vet is usually aware of the mistake having been made at the time of surgery and will have taken steps to repair it prior to waking the tomcat up. More commonly, excessive bleeding from the surgical desexing site/s is an indication that the pethas some kind of significant blood clotting disorder including: hemophilia, rodent poison ingestion or a low blood platelet number problem (e.g. platelet deficiency, thrombocytopenia, ITP).

If excessive bleeding from the surgical desexing site is observed, the animal needs to immediately go back to the vet or (if it is after hours) to the nearest veterinary emergency centerfor treatment and work-up. This is particularly so if the animal looks at all pale or white in the gums (pale or white gum colour is often a sign of severe blood loss and shock setting in). Animals with severe bleeding mayrequire a blood transfusion and supportive care (perhaps even an exploratory surgery to finda ruptured blood vessel) to save their lives.


6f. Failure to ligate (tie off) the testicular blood vessels adequately (uncommon).
This is the diagram presented earlier, which shows the reproductive and vascular anatomyof the entire male cat.

The reproductive and vascular anatomy of the entire male tomcat as it pertains to desexing surgery.

What you will notice from this image is that the spermatic ducts (vas deferens) and blood vessels supplying each of the cat's testicles arise from deep within the animal's abdominal cavity. These vessels exit the cat's abdominal cavity in the region of the animal's groin, via a natural hole in each side (right and left) of the cat's abdominal wall called the inguinal canal or inguinal ring (marked in purple). After exiting the abdominal cavity via the inguinal canal, these ducts and vessels run deep within the fat situated alongside the animal's penis and into the scrotum, where they unitewith the sperm ducts and blood vessels contained within the animal's testicles.

It is important to understand this anatomy because it has a bearing on what can happento the animal if the testicular blood vessels tear off or the vet accidentally fails to ligate the testicular blood vessels properly before cutting them (STEP 7 in section 4 of this page). If such an incident occurs, the cut and bleeding ends of the testicular blood vessels will not remain under the skin and in a site that is easily accessible. They will, instead, retract swiftly back into the feline's abdominal cavity and begin to hemorrhage out there, resulting in the animal developing a belly full of blood. The vet will then need to cut quickly into the animal's abdominal cavity in order to find the bleeding vessel, tie it off and thus save the animal. If the vet fails to do this, the cat could die from excessive testicular artery hemorrhage and blood loss.Even if the vet does find the bleeder in time, animals with severe testicular arterybleeding may require a blood transfusion and further supportive care to save their lives.

Author's note - one benefit of early age kitten neutering is that the blood vesselssupplying each of the kitten's testicles are tiny and narrow. They will rarily bleed to any significantextent even if they are not tied off (ligated) properly. In one clinic where I worked, the testicles of male kittens weighing under 1kg were merely torn off rather than knotted. No significantbleeding issues were encountered and surgical time was reduced to 30 seconds per kitten neuter.Click here to see our photographic guide to early age male kitten neutering.


6g. Renal failure (uncommon in young, healthy animals).
Although anaesthetic drugs are much less cardiovascularly depressant (depressant on blood pressure)and rough on the kidneys and liver these days, there is still the possibility that an individual cat or kitten may develop acute renal failure immediately after or some days after any anaesthetic procedure, even such a quick, routine procedure as feline neutering.

Animals can develop renal failure if their blood pressure drops below certain criticallevels during anaesthesia (e.g. if the animal receives a drug that suppresses its cardiaccontractility and heart-rate, resulting in reduced blood pressures). Kidneys require that acertain pressure of blood go through them in order for them to receive enough nutrients and oxygento stay alive and functional (they are sensitive to low blood pressures and become damaged easily). Animals can also go on to develop acute renal failure if they experienced a severe surgical complication that caused their blood pressures to fall critically during anaesthesia(e.g the animal experienced severe bleeding and blood loss during the anaesthetic - see 6e-6f).

Kidneys require a minimum systolic blood pressure of 90mmHg and a mean arterial blood pressureover 60mmHg to survive. Blood pressures below these levels are very dangerous.

Animals may also develop renal failure because they received an anaestheticor pain-killer drug (or both) during the surgical procedure that had toxic side effectson the kidneys. For example, NSAIDs (non-steroidal anti-inflammatory drugs) used forpain relief act by inhibiting the formation of prostaglandin, a common body-chemical initiatorof pain and inflammation (inhibiting prostaglandin production is how these drugs work to reduce pain). Body prostaglandins, however, also have an additional role in protecting the kidneys from the damaging effects of low blood pressure (in times of low blood pressure the blood vessels leading into the kidneys release prostaglandins, which causes these vessels to dilate and the kidneys to, therefore, receive more blood and oxygen).NSAIDs inhibit the protective action of prostaglandin in the kidneys, resulting in akidney that is more prone to becoming damaged if blood pressures fall (as they often do during surgery).

Additionally, because the kidneys are designed to filter waste and toxins from the body, a lot of commonly-used anaesthetic and pain relief drugs require these organs in order to be cleared from the body. Kidneys, particularly kidneys alreadycompromised by age, low surgical blood pressures or pre-existing disease, may not beable to tolerate these drugs moving through them and may, as a result, become injured and fail to function.
Renal failure after surgery is more common when aged animals (>8 years) are operated on. These older animals are more likely to already have some degree of renal compromise and the compoundingeffects of low blood pressures during anaesthesia as well as renal-toxic drugs (esp.non-steroidals), can be enough to push their kidneys over the edge. It is for this reason: to detect mild, sub-clinical renal disease that might be exacerbated by surgery, thatmost vets insist pre-anaesthetic blood panels being performed prior to performing surgery on older felines.

Young cats, however, are not immune from suffering the effects of acute renal failureafter surgery. Certain breeds of cat: e.g. Persians and Abyssinians and a number of others;are prone to a range of congenital renal defects and diseases. Animals affected with such conditionsare more likely to already have some degree of renal compromise by the time of neutering and the compoundingeffects of low blood pressures during anaesthesia as well as renal toxic drugs (esp.non-steroidals), can be enough to push their kidneys over the edge, even though they areonly young animals (and thus, presumably healthy). It is for this reason: to detect mild, sub-clinical, congenital renal disease that might be exacerbated by surgery, that many vets offer pre-anaesthetic blood panels prior to performing surgery on young cats. It is often a box that can be ticked on the anaesthetic permission form.

Animals that do develop acute renal failure after surgery will often become very sick over about 24-72 hoursafter surgery. They will drink excessively or not at all, they will go off their food, they will oftenvomit (the vomit may contain blood), they will become very depressed and listlessto the point of being non-responsive, they will become dehydrated, they will stop urinating (or only urinate rarely) and they may start to pass black, tar-colored faeces or diarrhea.

Animals presenting with these signs after any surgery must see a vet. Animalswith acute renal failure will require aggressive and intensive (and expensive) therapies to save their lives. Many animals with severe, acute renal failure will not recover.

The risk of post-operative renal failure can be reduced by letting the vet performa pre-anaesthetic blood profile on the cat, young or old, prior to surgery. In this way,early renal disease may be picked up. Vets can also reduce the risk of cats developing renal failureby performing swift surgeries; monitoring blood pressures during surgery and by not giving the animal non-steroidal drugs prior to surgery, only afterwards, as the pet is recovering.


6h. Anaesthetic death (rare but does occur).
Very rarely, but often enough that most vets will have encountered a few during their careers,a young "healthy" cat booked in for a routine desexing procedure will inexplicablydie. This is, needless to say, very distressing for the owner and for the veterinarian(having had one inexplicable death myself, I do vouch for this) and people willdemand answers. The fact of the matter is that, while in some cases we vets can determine thecause of an anaesthetic death (e.g. the animal bled to death because it had eaten rat poisonprior to surgery and no-one knew about it; the animal developed an acute, fatal anaphylactic reaction to an anaesthetic drug; the animal was not monitored properly during or after anaesthesia and died; the animal vomited on recovery, inhaled its vomit and died and so on), in a good many more cases the reason for death can not be determined. The animal simply died and we have no idea why. We presume that these animals may have had a pre-existing disease; suffered a sudden, fatal heart arrhythmia (a heart problem never picked up before); suffered a "stroke" (blood clot entering the brain) or thrown a blood clot into the lungs or heart, but we never actually find the cause of death.


6i. Tracheal damage caused by overinflation of ET (endotracheal) tubes.
During desexing surgery, a small tube is often inserted down the throat of the cat being operatedon in order to maintain a patent airway; prevent the inadvertent inhalation of saliva, vomitand other mouth secretions and permit the delivery of inhalational gaseous anesthetic drugsto the cat's lungs. This tube (called an endotracheal or ET tube) often has a small balloon near the tip (called a cuff), which is inflated with air after intubation to ensure that the tube fits snugly within the trachea (doesn't slide out) and does not permitthe passage of secretions or gasses around the outside of the tube (between the tube andthe inner wall of the trachea).

Very occasionally, a situation can occur whereby the balloon cuff of the endotracheal tube (ET tube) is inflated too much, resulting in damage to the lining of the cat's trachea.This damage can consist of a small split in the wall of the trachea or it may involvepressure damage to the entire circumference of the trachea in the regionwhere the cuff was located (this kind of pressure injury is called pressure necrosis). In rare circumstances, the entire trachea may break in half (into two sections), putting the cat into severelife-threatening respiratory distress.

Tracheal splitting and subcutaneous emphysema:
If a small split occurs in the tracheal wall, the cat will tend to present to the vet with a condition called subcutaneous emphysema (air under the skin). Subcutaneous emphysema is caused by air leaking from the hole in the animal's trachea and diffusing into the muscles and tissues beneath the animal's skin. The cat's skin will swell and expand with trapped air and the owner will feel a weirdbubble-wrap-like, crackling sensation when he or she pats the cat. Many owners say that it feels like the cat has crackly cellophane under its skin. Some cats withtracheal injuries and splits will also present with a harsh honking cough as a result of tracheal wall trauma and tracheal-lining irritation.

Although subcutaneous emphysema secondary to tracheallaceration can appear spectacular and alarming to the owner, it is seldom life-threateningin itself and will often resolve over the next few weeks once the hole in trachea hashealed and sealed. Although some of these non-complicated tracheal split cases do end uprequiring surgical intervention to repair the hole in the trachea and stop the emphysema from reforming, the vast majority of these simple cases do heal up fine with strict cage rest and antibiotics and time.

Severe tracheal splitting, subcutaneous emphysema and pneumothorax:
The only time that the subcutaneous emphysema condition can become life-threatening is if the leaking air dissects along the muscles of the cat's neck and enters the cat's chest cavityresulting in pneumothorax (air trapped between the cat's lungs and rib cage). This trappedair prevents the cat's lungs from expanding when it breathes, resulting in suffocationand even death. The cat with pneumothorax as a complication of tracheal splittingwill present with severe respiratory distress (rapid respiration, panting, blue tongue, cyanosis) in addition to its swollen, crackly, bubble wrap skin.

Cats presenting with pneumothorax as a complication of tracheal laceration will often requirechest drainage (a needle or a tube placed into the cat's chest to remove the trapped air) to correct therespiratory distress and enable the cat to breathe. Many cats affected with pneumothoraxwill also require urgent surgical repair of the tracheal laceration (surgically sealing up the hole in the trachea) in order to prevent the life-threatening pneumothorax from constantly recurring.

Severe tracheal pressure injuries and necrosis:
Cats that develop severe pressure necrosis of the lining of the trachea (pressure-induceddeath of the cells lining the trachea) are at risk of developing tracheal perforation and subcutaneous emphysema (+/- pneumothorax) if the tracheal damage becomes "full-thickness."Full-thickness means that the injury to the trachea extends from the innermost layer of the trachea to the outermost wall of the trachea. Full-thickness tracheal necrosis and laceration is a serious condition because it can result in the trachea rupturingcompletely (breaking in half). It is a condition that may require urgent surgical intervention.

Fortunately, however, most cats that develop pressure necrosis of the trachea do not ever progress this far in severity. Most cats, instead, just develop severe irritation, swelling, inflammation and even sloughing (rotting away) of just the tracheal lining in the affectedregion. Lasting days to weeks, this inflammation/sloughing process will cause the cat to show signs of significant tracheal irritation: the cat will develop a harsh, honking cough;the cat may appear to cough-up and swallow debris from the trachea (expectoration);the cat may gag up white or bloody froth and the cat may develop respiratory distress if secretionsfrom the inflamed airway blocks the windpipe. If the swelling of the tracheal lining is severe,the cat might also develop a high-pitched inspiratory wheeze (+/- respiratory distress)from narrowing of the tracheal airway. In severe cases, infection may set up in the injured regions, resulting in respiratory distress, a moist cough and even pneumonia (infection entering the lungs).

Diagnosis of tracheal lining necrosis is made using endoscopy (a camera inserted down the trachea).

Generally, tracheal pressure necrosis cases only require antibiotic coverage, cough suppressants (used with care) and strict cage rest to heal them, however, severe cases may sometimes need surgical intervention. If the animal does heal successfully, there is a chance of the animal developing a tracheal stricture or tracheal stenosis (scarring of the lining of the trachea thatcontinues around the periphery of the trachea) after a tracheal pressure injury. This scarmay cause narrowing of the airway, resulting in the animal developing a permanent wheeze (whistling sound on inspiration). In some cases, such scarring can even causeobstructive respiratory problems and respiratory distress signs requiring further medical and/or surgical intervention.

Severe tracheal rupture:
Cats with complete rupture of the trachea (trachea snapped in two) will present withsevere respiratory distress. These animals will need urgent surgical intervention orthey will die. Thankfully, these cases are rare.


Cats presenting with any signs of skin swelling, crackles under the skin or respiratorydistress or discomfort after surgery should be seen by a veterinarian as soon as possible.



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7. Late onset complications of neutering cats.

7a. Weight gain.
Not really a complication per se, but an often complained about sequelae of cat desexingsurgery.

Studies have shown that neutered animals probably require around 25% fewer caloriesto maintain a healthy bodyweight than entire male animals of the same weight do. This is because a neutered cat has a lower metabolic rate than an entire cat. Because of this, what tends to happen is that most owners, unaware of this fact, continue to feed their neutered male tomcats the same amount of food after the surgery that they did prior to the surgery, with the resultthat their cats become fat. Consequently, the myth of automatic obesity has become perpetuatedthrough feline-owning circles and, as a result, many owners simply will not consider desexing their cats becauseof the fear of them gaining weight.

Author's note: The fact of the matter is that most tom cats will not become obese simply because they have been desexed. They will only become obese if the post-neutering drop in their metabolic rateis not taken into account and they are fed the same amount of food calories as an entire animal. Any weightgain that is experienced can be reversed through not feeding the cat as many caloriesand treats.


7b. Preputial scalding and infection - a potential complication of early age desexing.
Normal testosterone levels are required in order for young male cats to be able to break down the adhesions between their penises and prepuces (penis sheaths) and therefore extrude their penises. Animals that are desexed very young (i.e. early age desexing) may not be capable of extending their penises from their penis-sheaths at all. These animals are thereforeprone to having urine pool within their prepuces during urination, resulting in urinescalding of the prepuce and secondary preputial infections and discharges. Vigilant hygieneand cleaning of the prepuce may be needed in these animals.


7c. Neutering didn't deliver the change (improvement) in problematic male behavior that you thought it would (e.g. behavioural problems such as aggression, dominance, marking territory, urine spraying and roaming have persisted despite desexing surgery).
Again, this is not really a complication per se, more a problem of unfulfilled expectations. A lot of owners only get their cats desexed as a means of trying to correctalready established male behaviours that are annoying or unsafe to the owner or pet (e.g. roaming, aggression, dominance, marking territory, urine spraying and so on).Such owners often become very disappointed when the desexing surgery fails to correctthese behavioural "defects" in their feline animal.

The trouble with having such expectations is that, while desexing a cat early may often go a good way towards preventing these adverse male behaviours from developing (one of the reasons we advocate early neutering), once these behaviours have become well established in the cat's behavioural repertoire (i.e. become part of its character), they may become difficult to reverse by desexing alone. The reason for this is that, over time,many of these adverse behaviours go from being purely hormonally-driven behaviours (i.e. treatable by removing the hormone responsible: testosterone) to learned behaviours, which arehard to unlearn. For example: a tomcat might initially start roaming the countryside because of a hormonally-driven imperative to find females and mate, however, over time, such a cat will soon learn that roaming the countryside is fun (e.g. it yields fun results suchas prey from hunting activities) and will therefore continue to do so, regardless of whether it has testicles or not. Dominance behaviours are also learned: a young male cat or dog might start pushing the leadership boundaries in your household because of rising testosterone levels, however, it will also learn what it get away with by the way you, the owner, react to its pushes for leadership.
Another major reason why desexing surgery often fails to deliver significant improvements in a cat's behaviour is that the behaviour being 'corrected' by desexing surgery is not a testosterone-induced behaviour! Many "bad" behaviours have nothing to do with testosterone and are a result of many other factors including: poor socialization, bad training, lack of "owner leadership",anxiety, fear, hierarchical relationships; environmental stimuli (smells, sounds, sights) and the need for communication (e.g. urine spraying can be a communication tool for the cat). Consequently, removing the testicles will not cure many of these problems. Twoexamples of potentially non-testosterone-dependent problem behaviours (aggression and urine spraying)are discussed below.

Example 1 - feline aggression:
Aggression is a good example of a potentially non-testosterone-dependent problem behaviourthat may not be cured by desexing alone. Many owners with aggressive cats try to cure their pet's aggressive behaviour by desexing surgery. The trouble with this treatment modality is that the feline's aggressive behaviour may not be being caused or contributed to by testosterone and, thus, desexing may not help matters at all.

There are thought to be around 11 different classifications of aggression in the cat and, of these, only acouple (e.g. inter-male aggression, territorial aggression) may be improved by neutering alone:most of the other forms of feline aggression will not be helped at all by surgery. For example: fear-induced aggression (fear-biting) is generally contributed to by the cat's past experiences; certain environmental factors; pet hierarchy factors; owner reinforcement factors and the emotional nature of the cat, not by testosterone. Desexing will thus not fix fear-aggression. Inter-male aggression (tomcat-to-tomcataggression, especially in the breeding season) and some forms of territorial aggression, however, can be contributed to by high testosterone levels and, therefore, desexing cat-aggressive entire males and territorially-aggressive males may go some way towards helping the issue, provided the problem hasn't been going on too long and the animal hasn't now simply 'learned' to dislike other cats on sight.

Example 2 - tom cat urine spraying:
Urine spraying is another example of a potentially non-testosterone-dependent, non-castration-responsiveproblem behaviour that many owners try to "cure" by neutering surgery. And for the most part, the treatmentworks. Urine spraying is mostly a territorial or sexual marking behaviour that is most commonlyencountered in entire male tom cats. In up to 87% of entire tomcats that present withurine marking problems, desexing surgery alone will effect a cure in these animals. There is a subset of cats, however, who urine spray for reasons that are not sexual or territorial, including:fear, anxiety (nervous spraying), aggression (urine spraying can be a form of passiveolefactory aggression committed by one cat against others in the household), communicationand various medical problems. In these cats, feline desexing surgery may not resolve or reduce problem urine spraying behaviours at all.

Ovarid or megestrol acetate can be used to effect testosterone inhibition and aid in the treatment of testosterone-mediated behavioural and medical problems in the male cat including urine spraying.Author's note: certain testosterone-mediated problem behaviours such as inter-male aggression,urine spraying and various hypersexualised behaviours may not resolve with desexing surgeryalone because of presumed alternate-sources of testosterone production in the body.Although the testicles are the major source of testosterone in the feline body, otherglands (e.g. in particular the adrenal glands) may produce it too, resulting in some testosterone-mediated behaviours persisting despite desexing surgery. The spraying of vertical surfaces with urine (urine spraying, urine marking) is an excellent example of this - although many cases are 'cured' by desexing, the problem often persists in some toms despite desexing surgery because ofpresumed alternative testosterone sources.

Cats whose testosterone-mediated behavioural problems have not resolved after desexing surgery may be able to be treated successfully with the administration of various "anti-testosterone" medications including: MPA (medroxyprogesterone acetate), megestrol acetate (tradenames include Ovarid), delmadinone acetate (tradenames include Tardak) and proligestone. These progesterone-based drugs work by opposing the effects of testosterone in the body and effectively neutralise the effects of any testosterone coming from alternative sites in the body.




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8. Frequently asked questions (FAQs) and myths about feline neutering:

This section outlines some of the commonly held myths and misconceptions about male cat neutering surgery and answerssome of your commonly asked questions.

8a. Myth 1 - All desexed cats gain weight (get fat).
I have previously discussed this topic in other sections of this webpage: it is a commonly heldbelief that is, quite simply, not true.

Studies have shown that neutered felines probably require around 25% less caloriesto maintain a healthy bodyweight than entire male cats of the same bodyweight do. This is because a neutered animalhas a lower metabolic rate than an entire animal does. Because of this, what tends to happen is that most owners, unaware of this fact, continue to feed their neutered male cats the same amount of food calories after the surgery that they did prior to the surgery, with the resultthat their pets become fat. Consequently, the myth of automatic obesity has become perpetuatedthrough the cat-owning circles and, as a result, many owners simply will not consider desexing their tomcats becauseof the fear of them gaining weight and getting diabetes and so on.

Author's note: The fact of the matter is that tomcats will not become obese simply because they have been desexed. They will only become obese if the post-neutering drop in their metabolic rateis not taken into account and they are fed the same amount of food calories as an entire animal. Any weightgain that is experienced can be reversed through not feeding the pet as many caloriesand treats.


8b. Myth 2 - Desexed male cats lose their drive to hunt vermin.
Although this has yet to be proven, many owners of "mousers" (cats kept to keep rodentand vermin numbers low) will refuse to desex their cats out of the fear that their animals will nolonger have any drive to do the work required of them. They believe that, withoutits testicles (without testosterone), the animal won't catch and kill mice and rats.

As was discussed in section 7c, however, there are many kinds of behaviours, these predatory-type behaviours included, which are not mediated by testosterone levelsat all. These predatory hunting behaviours are instinctive, survival-focussed drives that have been built into the cat species by genetic selection and environmental and preyinfluences over many centuries. Removing the animal's testicles and therefore its testosterone levels should not really have any bearing on the animal's drive to perform these instinctive, non-testosterone-fueled, hunting activities.

One way to consider the matter is to look at the female of the species. Female cats hunt and killrodents as well as male cats do and yet they have no testicles and nowhere near as much testosterone as a male cat. Now, naturally, female cats do have less size, muscling, strengthand stamina than their male counterparts do and, consequently, they may not be as physically adept at certain tasks (e.g. bringing down large-sized vermin) as a male animal.Their drive to fulfill these tasks, however, is just the same, even if their physicalityis not.

Author's note: one could well argue that a tomcat might hunt better if it does not havemale hormonal urges distracting it from the task at hand.

Author's note: neutered tomcats do not grow as bulky, heavy and broad-headed and broad-shouldered as entire tomcats. One could well argue that a lighter, sleeker, neutered tomcat might perform better as a mouser: it will be able to fit into smaller spaces where mice and rats hide;it will jump and land and tread more lightly (making it more capable of creeping up on prey)and, with less weight and bulk to carry, it may even prove to be a faster ambush predator.

Author's note: the only time that a male cat's hunting performance might be adversely affected by desexing surgery is if the cat is allowed to get fat after desexing (point 8a). Fat, neutered cats have less muscle-bulk, strength and stamina than an entire male animal and may, therefore, not be as physically adept at performing certain tasks as an intact male.


8c. Myth 3 - Without testicles, a male cat won't feel like himself (i.e. he "won't be a man").
It is common these days for humans to attribute human feelings and emotions (e.g. love, sadness, grief and so on) onto their animals and, in doing so, make them out to bemore human than they actually are. Cats certainly have an understanding of concepts like affection and companionship and needing to behave to fit in with the family and receive food. But to thenextrapolate their needy, cuddly behaviour further, as many pet owners do, and claim that these animals act well-behaved and cuddle up to us as a sign of their "love" for us is probably a little far-fetched. In a similar fashion, this testicle myth is merelyanother common example of human emotions being incorrectly attributed to our pets. What often happens is that, because the owner (often a large, burly guy with a large testicled tomcat) believes that he himself would feel incomplete and therefore "not a man" without hisown testicles, then so will his tomcat feel the same way if his testicles are taken away.

The fact of the matter is that cats probably barely even notice that their testicles are missing.They certainly don't seem to be in any way depressed about it (as a human in the same situationwould) and tend to go about their feline business just the same as always once the procedure isperformed. If tom cats were truly depressed or worried about being neutered and not having theirtestes, then there would be some sort of long term depression, shyness or behavioural change seen in them and this just does not seem to occur.

Despite me telling you all this, if you are still concerned that your animal will not be "a man"after the neutering surgery is done, then consider getting your pet some testicular implants to replace the real testicles removed at surgery. Owners of show animals commonly have them put into their cats' scrotums so that they seem more completeand pet owners can request these too. They cost a few hundred dollars on top of the normal costs of desexing. The prosthetic testicles are implanted at thetime of castration and so, as far as the cat's appearance goes, nothing will have seemedto have changed after the surgery is done. Peace of mind.


8d. Myth 4 - Male cats need to have sex before being desexed.
No, no and no! Cats do not need a sexual experience to be in any way complete eitheremotionally or behaviorally. Similar to the myth above (myth 3), this is a situationwhere human emotions and desires have been superimposed on top of what is best for the animal. Allowing the pet to have a sexual experience prior todesexing may well lead to some established behavioural problems developing that persist even after neutering has occurred (e.g. roaming, territorial aggression). The"experience" could also result in an unwanted litter of kittens being born.

You could argue that, from a human emotional viewpoint, it is cruel to let the cat experiencethe "pleasures of sex" only to then take it all away from him by desexing. Better forhim to never know what it feels like because then he won't know what he's missing.


8e. Myth 5 - Male cats should be allowed to father (sire) a litter before desexing.
Allowing a litter to be born simply because you feel that the 'cat should be allowed tobe a father' is very irresponsible and just results in more and more unwanted, dumpedkittens finding their way into pounds and shelters and waste-disposal units.


8f. Myth 6 - Vets just advise neutering for the money and not for my pet's health.
Whilst it is true that desexing, along with vaccinations, worming and flea prevention, is one of the main bread-and-butter activities of the veterinary profession, we do not advocate the procedure just for the money. Face it, if money and not the animalwas all that we considered when making these decisions to operate or not, then vets in Australia (can't vouch for the rest of the world) would still be tail-docking and ear-docking pets and we would now be starting to see many veterinary surgeons dabbling in pointless cosmetic surgery to suit an owner's particular aesthetic tastes (as does occur overseas).If money was our only concern, veterinarians would not be now promoting 3-yearly vaccineregimens instead of the previously popular and highly lucrative yearly vaccinations.

Surgical procedures are not without risk to the animal (see section 6 on surgical complications) and, therefore, vets do not advocate surgical procedures, including desexing,if there is no benefit for that animal or society as a whole. The benefits of surgery must outweigh the risks. Vets advocate the desexing of male and female cats for all of the population control, genetic disease control and medical and behavioural benefits previously discussed (section 2).

Another thing to consider is that, by advocating the mass desexing of animals, veterinarians are essentiallydesexing themselves out of business. Fewer kittens around means fewer vaccinations and fewer clients. Veterinarians could also be making a lot more money out of all of the caesarean sections and dystocias (inability to give birth) and mammary cancers and testicular cancers that would be the result if we weren't pushing desexing so aggressively.


8g. FAQ 1 - Why won't my veterinarian clean my cat's teeth at the same time as desexing him?
Veterinarians the world over have a policy of not performing a "dirty" surgery at thesame time as a "clean" surgery.

A dirty surgery is a surgery or procedure whereby the tissues involved already have a high level of bacterial contamination, such that many bacteria are likely tobe released into the animal's bloodstream and surrounding tissues as a direct result of the surgical or medical procedure. Dentistry is a good example of this - when an animal gets its teeth cleaned, millions of bacteria from the teeth and gums are released into the animal's blood stream.

A clean surgery is a surgery or procedure with minimal bacterial contamination risk. Desexing and orthopedic surgeries are common examples of clean surgeries.

The reason why most veterinarians will not perform a dirty surgery (such as a dental scaleand polish) at the same time as they will a clean surgery (e.g. desexing) is because ofthe risk that bacteria from the dirty surgery will travel throughout the animal's bloodstreamand lodge in the site of the clean surgery. This could result in infection setting up in thesite of the clean surgery, which could be disastrous in situations like orthopedicoperations and desexing surgeries, which are supposed to remain as sterile and bacteria-free as possible.


8h. FAQ 2 - Why shouldn't my vet vaccinate my cat while he is under anaesthetic?
In order for vaccines to work effectively, the animal needs to have a fully functionalimmune system that is capable of responding to the vaccination contents. See our great "How vaccines work"page for more details on the immune response to vaccination.

The reason why most vets will not vaccinate an animal that is undergoing an anaestheticprocedure is because the animal's temperature will often fall to below normal levels when it is underan anesthetic. Since many of the body's immune cells do not work as wellwhen body temperatures are very low, there is the risk that the vaccination might failto induce the full immunological protective response if it is given to a cold animal. Hence the reason why vets don't vaccinate anesthetized cats.


8i. FAQ 3 - Is feline desexing safe? It's just a routine procedure isn't it?
There is no such thing as a routine or "safe" anaesthetic procedure, regardless ofwhether the procedure is elective or not. There is always the risk, albeit small, that anormal, healthy individual animal or human may not wake up from an anaesthetic processor that it will develop a potentially fatal complication from having had surgery oranaesthesia performed (e.g. renal failure, sepsis).

In the case of feline neutering, yes it is a "routine" procedure insofar as we vets performthousands of them every year. For the most part, the complications of the procedure areexceptionally rare: very very few animals die or suffer severe, life-threatening complicationsas a result of cat neutering surgery. To say that the procedure is perfectly safe, however, would imply that nothing bad can ever happen and this is simply not true. Section 6of this page lists a whole string of operative and post-operative complications thatcan occur, some of which can be fatal.


8j. FAQ 4 - My veterinarian offered to do a pre-anaesthetic blood screening test - is this necessary?
As mentioned in an earlier section (section 6i), anaesthesia does drop the cat'sblood pressure and place the animal's kidneys and liver under strain, both from the lower blood pressuresand from the need to metabolize and excrete the drugs from the body. The pressure onand risk of damage to the kidneys and liver from an anaesthetic procedure is much greater if those organs (liver and kidneys) are already compromised by disease or scarring (old-age changes).

The role of a pre-anaesthetic blood panel is to detect significant kidney and liverpathology before the cat has an anaesthetic so that the vet can decide uponsafer, alternative drugs or anaesthetic strategies or decide to not do the procedure at all (e.g. if it elective), thereby reducing the risks of a pet succumbing to post-operativerenal or liver failure. The reason that a blood test is crucial in detecting if any pathology(disease) exists is because the veterinarian often can not tell what is going on in a cat's liver or kidneys from a clinical exam alone. The pet may look totally fineon the examination table and yet have only a small bit of renal function remaining.All the owner may notice at home is that the animal is drinking more water than normaland even this might not be all that obvious (especially if you have more than one cat).

Most vets these days offer a pre-anaesthetic blood panel to all animals so that all ownershave the option of checking their pet's kidneys and liver before any anaesthesia isperformed. Although this test is much more valuable in older animals (> 8 years old) because theyare the age group most likely to have some degree of kidney or liver compromise, young animals may also benefit from pre-anaesthetic blood testing. Young animals are not immune from suffering the effects of acute renal or hepatic (liver) failure after surgery. Certain cat breeds(e.g. Persians, Abyssinians and many others) are prone to various congenital renal defectsand affected animals are very likely to have some degree of renal compromise at a young age - this disease may first be picked up on a pre-anesthetic blood screen.

So, as to the question, "Is pre-anaesthetic blood screening necessary?" - I would sayyes. In cats over the age of 8 years, I would say that blood screening is very necessary becausethese older animals commonly develop organ dysfunction, which might only be detectable ona blood screening test. Diagnosing the problem before anaesthesia and taking it intoaccount during anaesthesia may well prevent the animal from developing acute renal or liver failureafter surgery. In animals under 8 years, I would say that blood screening is necessary, butmore optional. Playing the odds, it is less common for an animal under 8 years of age to have severe liver or renal disease. However, if you are the kind of owner who wants tocover all of the safety bases for your feline friend, I would advise pre-anaesthetic blood screening in all animals that have an anaesthetic. This way, if your cat does happen to be oneof the animals that has developed young-age kidney or liver issues, the problem will be detectedprior to surgery commencing (it will also allow earlier diagnosis and treatment forthe condition to start, which is beneficial for the prognosis).


8k. FAQ 5 - When is desexing not safe to do?
Desexing is not safe to perform on any cat which has a medical condition that precludes it fromhaving a safe anaesthetic. Any disease or condition that results in compromise to theanimal's heart rate, heart contractility, heart rhythm, respiratory function orability to metabolize (break down) and excrete drugs may be exacerbated, perhapsterminally, by general anaesthesia. Examples of such diseases include: heart failure, cardiomyopathy,hyperthyroidism, heart arrhythmias, pneumonia, shock, sepsis (systemic infection, causing shock), renal failure, liver failure and many more.

Any animal with a severe blood clotting disorder should not be operated on becauseit will not be able to clot its blood during the surgery and could well hemorrhage to death. Examples include: platelet disorders, platelet deficiencies, hemophilias A, B and C, other congenitalblood clotting disorders and rodenticide poisoning.

Any animal with severely infected or diseased skin in the region of the surgical site should not beoperated on. These animals are likely to have a high level of superficial bacteria andthis could well result in wound infection and wound break down.

Cats with diarrhea should also not be castrated. Because feline castration wounds are left open to heal, there is a risk that watery faeces (diarrhoea) may enter the open surgical sites, setting upsevere infections and abscesses.



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9. The cost (price) of neutering a tomcat:

Much as I would love to be able to do so, to attempt to place a flat $ figure on the costs of desexing a male cat would be grossly irresponsible of me and quite impossible todo. The cost of desexing male cats is greatly variable and varies from place to place and regionto region. It depends on many factors including: the size of the vet clinic, the competitionthe vet clinic has, the nature of the clinic (e.g. is it a shelter clinic), the suburb theclinic is located in, whether the animal is a cryptorchid or not and so on.

In this section, I will attempt to give you an idea of the costs and the range of pricesthat may exist in one town/city when you are considering getting your cat neuteredin Australia. (The principles discussed here will most likely apply to any city in the world). I will outline the ways that vets arrive at these prices and discuss ways that youcan source lower cost and discount neutering.

9a. The usual, typical cost of neutering a male cat at a veterinary clinic.
For this section, I rang 9 of the veterinary practices in Canberra, Australia, asking about thecosts of routine desexing for a male cat. The clinics were chosen atrandom, aside from the fact that five of them were large, multiple-vet practices and the other fourwere small 1-2 vet practices. The prices (in Australian dollars) are listed below (for legal reasons, I can not identify the clinics I contacted).


Clinic 1:
Male cat neutering - $140

Clinic 2:
Male cat neutering - $114

Clinic 3:
Male cat neutering - $135

Clinic 4:
Male cat neutering - $155

Clinic 5:
Male cat neutering - $160

Clinic 6:
Male cat neutering - $140.70

Clinic 7:
Male cat neutering - $123.30

Clinic 8:
Male cat neutering - $113.50
This clinic also featured a 10% discount for multiple cats.

Clinic 9:
Male cat neutering - $85
This clinic also featured a 10% discount for multiple cats.


Summary:
Highest price: $160.

Lowest price: $85.

You can see from this small survey that there is some variation in price and that, therefore, it paysto shop around. In this case, the difference in price would have been quite significant hadyou shopped around (you would have saved yourself $75). Veterinary clinics are competitive entities and many will attempt to undercut others on price to secure you as a client.


How do vet clinics arrive at their charges?
Overall, veterinary clinics charge a lot for veterinary attention, surgery and medication for two main reasons: the high costs of running the practice (veterinary clinics are expensive to own and maintain)and the high costs of veterinary drugs and diagnostic equipment (drug companies charge vets a lot of money for the drugs we purchase). Staff costs are high, land rates are high, equipment costs are high and many drugs only have a certain limited shelf-life (used-by date), after which they can not be used and are therefore wasted.

As a general rule, the larger, multiple-vet veterinary clinics tend to charge more fortheir surgical procedures than the smaller one to two man vet clinics do. This is often because the larger clinics have massive staffing and operational overheads that needto be met through higher charges, however, higher costs can also sometimes be a sign ofthe quality of monitoring and patient care that your pet is receiving. The otherreason large vet clinics tend to charge a lot more for their services is becausethey can. They have enough clients and reputation built up to not need to compete foryour business: if you can't afford their fees, they don't mind if you look elsewhereas it doesn't affect their bottom line. On the flip side, sometimes large clinicswill actually charge less for their routine procedures, such as neutering, because they benefitfrom economics of scale (big places often save a lot on drugs and medications becausethey make such large orders with drug companies that the drug companies give them significant discounts). In my small survey, clinics 2 and 7 had some of the most competitive pricesand yet both were large, high-quality, multiple-vet practices that could have been expected to charge a lot more.

Smaller clinics, on the other hand, do tend to charge less for their services, dependingon where they are based and how much competition they have. Smaller clinics struggleto get a foothold in the market and will often have very competitive prices to getroutine surgeries, such as castration surgeries, through the door. The two clinics withthe lowest prices in my survey were both small, 1-3 man vet clinics. You shouldbe very choosy when opting to have your pet's surgery done through a small clinic, however: whilst most small vet clinics are run by highly competent people who provide a very good standard of care, some small clinics remain small because people know not to go to them (their service might be bad, their premises unclean or their patient care and monitoring not up to scratch). As a general rule, however, most vetsin big and small clinics alike have done thousands of feline neutering surgeries (they're probably one of the easiest surgeries we vets can perform) and it is unlikely that you will experience a problem even if you do go to a tiny little clinic in the middle of nowhere for your services. For example, the clinicthat offered the lowest-priced services in my survey ($85 for a feline neutering surgery) is a small clinic, however, it is run by an excellent surgeon who performs really good work. i.e. low procedural costs and small practice size does not always equate to poor service.

Suburb also makes a huge difference to the price of services. Clinics in affluent suburbs, be they big or small (they are often large clinics), often charge much more for their servicesthan clinics in lower socioeconomic suburbs. Their clients can afford to pay more. In my survey, suburb wealth was actually one of the most significant factors dictating the costs of neutering services.The second-most expensive clinic surveyed (Clinic 4) was a large, multi-vet practice located within a very rich area of Canberra, as was the third-most expensive clinic (clinic 6). The next-most-expensive clinic (Clinic 1) was only a small, one-man practice, but it could charge high fees because it was also locatedwithin a wealthy area of Canberra (in a similar location to clinic 4). I can not comment on thesuburb wealth of the highest-cost clinic in the survey (clinic 5) as I am unfamiliar withthe socioeconomics of the region of the A.C.T. it was located in.

Competition also makes a huge difference to the price of neutering services. Clinics in suburbsor towns that have many vet clinics often charge less for their services than vetclinics in towns where there is little to no competition.

Costs will also be increased if your cat experiences complications during the surgical procedure(e.g. needs a blood transfusion during surgery) or if it has a neutering surgerythat is more complex to perform than normal (e.g. the cat is cryptorchid and the vet needsto enter the animal's abdomen to find the retained testicle). Added costs will also apply if the cat needs pre-anaesthetic bloods done or needs additional procedures performed (e.g removal of a retained baby tooth, dewclaw removal, microchipping and so on).


9b. Where and how to source lower cost and discount neutering.
Once again, for legal reasons, I can not name the names of veterinary clinicsthat offer discounted and low cost neutering services. I can, however, provide tips onhow and where you might find them.

1. Ring around:
For the cost of a couple of phone calls to different clinics in my area, I was able todiscover that the price of feline neutering varied by as much as $75. By shopping around, you can often find lower cost veterinary clinics in and around your area.

2. Don't forget to look at clinics in lower socioeconomic areas:
Just because you live in an affluent area does not mean that you have to pay affluentarea prices for your vet services. There is no rule to say that just because you livein a wealthy suburb, you need to go to a vet clinic in that suburb. Try lookingoutside of your area. A lot of veterinary clinics in lower socioeconomic areas provideperfectly good services (certainly, most can desex a cat with no trouble at all), but do notcharge the kinds of prices that rich suburb clinics do. This was certainly borne out inmy survey - the highest cost clinics were the wealthy suburb clinics.

3. Consider having your cat desexed by a shelter or pet charity such as the RSPCA:
Shelters these days often have large vet clinics attached to them, with veterinarians thatperform thousands of desexing surgeries every year (shelter vets probably perform far moreroutine animal desexings than most other GP vets would do). These charity organizations tend to charge a good deal less for their services than commercialized private vet clinics do. Pensioners in particular can often receive good discounts for services at these places.

4. If you are buying a cat, consider buying your feline friend from a shelter, pound or pet charity such as the RSPCA:
These animals are normally sold to you already vaccinated, neutered and microchipped.


9c. Free neutering.
It is very uncommon for any veterinary clinics to ever offer their clients free neutering. Neutering an animal for free is essentially a business loss to that clinic.

If youlive in a place where there are active, charity-run or government-operated cat control programs going on (e.g. in India and Cambodia where street cats and pet cats are desexed for free to reduce population numbers and the spread of diseases such as rabies), it may be possible for you to get a pet desexed for free.



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10. Alternatives to neutering your male cat:

Owners who do not elect to get their tomcats desexed often request other ways of preventing or managing the breeding, behavioural or medical problems faced by theirentire male pets. Which preventative measures and treatment options can be offered reallydepends on what the owner is trying to achieve. Owners just looking to prevent theircat or cats from breeding can make use of a range of birth/pregnancy control measuresavailable (sections 10a-10f). Owners just looking to control or manage testosterone-mediatedbehavioural or medical problems can look at option 10g. The reality is, however, that no one of these alternativemeasures alone will manage all of the problems of overpopulation, behaviour and testosterone-mediatedhealth issues like desexing will. Additionally, many of these alternative solutions do come with significant side effects and health risks of their own. Desexing is always the best choice.


IMPORTANT: Check your local state and regional laws before opting for any ofthese feline desexing alternatives. Animal population control laws are changing and increasing all the time. It may be illegal for you to keep a non-breeding-purposes (i.e. an entire male cat not owned by a registered breeder) entire male cat on your property. Certainlywhere I come from (the A.C.T. - Canberra), it is illegal to keep a non-breeding-purposestomcat entire over the age of 12 weeks.


10a. Feline birth control method 1 - physically separate the tom cat from the queen and prevent roaming.
If your main concern is preventing your entire male cat from impregnating one ormore of your entire females or other people's cats in the neighbourhood, you can devise ways of preventing the tom from physically accessing your females (queens) and leaving your property.

This is a scenario that commercial and show cat breeders have to deal with all the time: they can't get theirstud male desexed, but do not want him to breed ad libitum with everyone. In thesesituations what breeders tend to do, and what you can do too, is house their cats (males andfemales) individually in specially-constructed, escape-proof cat runs (cat aviaries) so that male cat escape and mismating (inappropriate mating and impregnation) can not occur.

Note that simply constructing a separate fenced-off yard is not enough! It needs to be escape proof and that includesputting a roof on it. Many tomcats will scale massive heights and climb high fences to reach a female in heat.

Just keeping the tom cat away from the queen while she is in heat (in season) is also no guarantee ofher not falling pregnant. For starters, most pet owners can not identify accurately enough when a female cat's season starts and ends, particularly if the female cat is naturally affectionate (the owner wonders: is she in heat or just being her normal affectionate self?). Most female cats show no obviousoutward physical signs of being in season (e.g. they do not get the huge swollen vulva thatbitches in season do) and so owners can't tell just by looking at them. Also, some queens make identifying heat symptoms even harder for their owners by deliberately not displaying them in thepresence of their owners; only when let outside (i.e. in the environment of male cats).

To make things extra annoying and tricky, female cats are seasonally polyestrous. What this means is that, during the breeding season, the female cat's reproductive cycle will constantly alternate between being in season and receptive to mating (termed 'in heat' or 'in estrus') and beingout-of-heat and not receptive to mating (termed the interoestrus period) until such a time that the cat is either mated (+/- falls pregnant) or the breeding season ends (i.e. in winter). The in-heat, fertile, estrus periods last for around 1-20 days (average 3-10 days) at a time and the interestrus periods last for about 2-20 days (avg 8 days) at a time. The entire breeding season of the female cat lasts from Spring until Autumn. The long andthe short of it is that female cats may start a new heat every 3-40 days (average is every 2-3 weeks) for up to 9 months of the year! With breaks of only about 8 days (range 2-20 days) between fertile estrus periods, that's a lot of cat separating to do and a lot of female calling to put up with! The margin for error is huge. Moreover, this separation technique will not stop your male cat from escaping its yard and wandering off to find other neighbourhood females to mate with.

Even if you can manage to separate your male cat from any entire females, thereby preventing pregnancy, not desexing your male animal will do nothing for his behaviour or his health. He will still be inclined towards showing unfavourable entire-male behaviours (roaming, aggression, dominance, territory marking, urine spraying etc.) and he will still be prone toa range of testosterone-mediated health problems.

The best option is to get the male and female animals in your household desexed if theyare not registered breeding animals (you will be required to by law in certain states). There are important behavioural, medical and population-control benefits to be gainedby having each of the feline sexes desexed.


10b. Feline birth control method 2 - spey (spay) your queen cat.
It never ceases to amuse and amaze me how many owners (particularly male owners) are horrifiedby the thought of having their male animals desexed and yet will happily get theirfemale animals desexed, even though female cat desexing is a far more invasive and riskyprocedure to perform than male cat neutering is. It possibly harks back some underlying culturalbelief that pregnancy is the woman's problem.

It is however, an option. If you do not want your male animal to impregnate the femaleanimals in your household, you can elect to have the females desexed so that the male hasnothing to mate with. Certainly, there are important health benefits to the female cat if she is desexed and desexing her will prevent tomcats outside of your household from coming overand getting her pregnant.

Not desexing the male animal in this situation, however, will do nothing for his behaviour or health. He will still be inclined towards showing unfavourable entire-male behaviours (roaming, aggression, dominance, territory marking etc.) and he will still be prone toa range of testosterone-mediated health problems.

The best option is to get the male and female animals in your household desexed if theyare not breeding animals (you will be required to by law in certain states). There are important behavioural, medical and population-control benefits to be gainedby having each of the sexes desexed.


10c. Feline birth control method 3 - "the pill" and female oestrous (heat) suppression.
There are a number of ways to suppress estrus (heat, season) in female cats and therebyprevent them from becoming impregnated by entire male cats. Most of these solutions involve manipulating the female animal's reproductive cycle (estrus cycle) usinga range of reproductive hormone and reproductive-hormone-like chemicals. Some of these include: progesterones (progestagens) and progesterone-like chemicals and testosterones and testosterone-like anabolic drugs.

The problem with many of these hormonal estrus suppression solutions is that they can have potentially devastating, life-threatening and/or aesthetically displeasing side effects.

Progesterones:
Ovarid or megestrol acetate can be used for heat suppression and pregnancy prevention in the female cat.The progesterone and progesterone-derived drugs commonly used to temporarily or, with repeated use, permanently suppress estrus in the queen include: medroxyprogesterone acetate (MPA), megestrol acetateand proligestone. Having less or fewer toxic side effects in the cat than the testosterone-based products, progesterones are the most common drugs used for estrus suppression in the queen. Theyare not, however, without certain important potential side effects.

Common side effects of progesterone use in the queen include: lethargy (sleepiness);increased appetite; weight gain and, occasionally, loss of hair or change in hair colour andshrinkage of the subcutaneous tissues (pitting of the skin) at the site of injection. Insulin resistance and diabetes mellitus may also be induced by long-term progesterone usage as can growth hormone problems like acromegaly. Progesterones can sometimes mimic the effect of corticosteroidsin the cat, resulting in adrenal gland suppression and a potentially life-threateninginability to make body corticosteroids ('stress-support' hormones) during periods of stress or illness (a condition known as Addison's disease or Addison's crisis).

Progesterone drugs are metabolised by the liver and should never be given to animalswith liver disease.

Some queens treated with progesterone products have been found to develop severe mammary enlargement, mammary nodules and even nasty mammary tumors (breast cancer).

In breeding animals, the use of certain oestrous-suppressing progesterone drugs has been found to result in reduced fertility for many individuals, thereby reducing the affected animals' value as breeding animals. Permanent infertility can be inducedif the animal receives long term, prolonged progesterone treatments or is given progesterone prior to its first cycle (never give progesterones before the first season).If a cat is to be bred following estrus suppression, it should be bred on the second seasonafter the progesterone medication is discontinued.

The incidence of false pregnancy (also called pseudopregnancy or phantom pregnancy) may also be increased by the use of progesterones.

Animals treated with progesterone whilst already pregnant may have delayed parturition, resulting from a failure of normal hormonal birth-induction processes(i.e. the cat does not receive the 'signal' telling her body when to give birth). This delayed parturition results in the death and mummification of the fetuses inside the womb. Affected animals will often need a caesarean section togive birth and/or remove deceased foetuses. The milk production of such animals (ones given progesterone while pregnant)will also be adversely affected by the progesterone usage (the animal's milk production is inhibited by progesterone) and any live kittens born by C-section may require milk supplementation and hand-rearing.

Female feline pyometra (pyometron) a complication of hormonal heat suppression (the pill) in female animals.More catastrophically, the use of certain heat suppressant progesterone drugs (e.g. medroxyprogesterone acetate, prolonged, repeated doses of megestrol acetate) has been shown to increase the risk of the cat developing pyometron or pyometra - a severe, life-threatening infection and abscessation of the animal's uterus. Many cats that develop pyometra need to bedesexed to save their lives and those that are treated medically may not be able to go on to produce viable litters due to permanent uterine damage and scarring. The picture opposite showsa distended cat uterus full of pus pockets (abscesses), typical of pyometra. The syringe abovecontains some pus that was drained from the uterus (this is nasty stuff, full of bacteria).
The risk of pyometron and other uterine disorders does not seem to be as high with proligestone and infrequent (non-prolonged) megestrol acetate use as it does with some of the other progestagen products. The risk of uterine disorders is also thought to be reducedif the progesterone medications and estrus suppression is started in the winter months (during trueanestrous - uterus "off-season") prior to the breeding season beginning and the uterusstarting to enlarge and ready itself for possible pregnancy.

Author's note: of all of the progesterone products marketed for this purpose, proligestone(proligesterone) is considered to be one of the safer ones, with the lowest incidence of side effects.It is traded as Covinan. Megestrol acetate has more side effects, but these are nottoo common provided the drug is used according to instructions and not for prolongedperiods of time. The use of medroxyprogesterone acetate (MPA) is not recommended at all forthis purpose because it stays in the body for many months and has a high incidence of severereproductive and mammary side effects.

Author's note: in recent years a slow-release hormonal implant containinga progesterone-like drug called levonorgestral has been developed that will suppressheat for 12 months in the cat. The drug is thought to have few side effectsaside from cystic endometrial hyperplasia (cystic enlargement of the mucous glands lining the uterine wall), a condition that can result in mucometra (uterus full of mucus)or pyometra (uterus full of bacteria and pus) in some cats.


An example of a dosing regimen for estrus suppression in the queen using megestrol acetate:
This information is provided for educational purposes only - it is not a recipe tostart dosing your own pet at home. This drug must be used with veterinary guidance - never self medicate your cat without a vet examining your cat and instructing you on what to do. This drug may not be safe for your particular pet.

Megestrol acetate use should begin before estrus starts, in the winter months (during trueanestrous - uterus "off-season") prior to the breeding season beginning and the uterusstarting to enlarge and ready itself for possible pregnancy.
Dose rate: 2.5mg/day for up to 8 weeks (for people who want to suppress heat in the short term)or 2.5mg/wk for up to 18 months (for people who want to suppress heat for the longer term).

Megestrol acetate can be used to suppress heat signs in a female cat that has alreadystarted to come into season (although, it is less ideal than if the cat had never started to cycle).
Dose rate: 5mg daily for 3 days and then 2.5mg/wk for up to 10 weeks.
The vast majority of cats will come out of season and stop calling within 1-2 weeksof this protocol starting.

In cats that have recently had kittens, the megestrol acetate should be started as soon as possibleafter birthing to get the cat to stop cycling.

Again, never use any progesterone drug without advice from your own veterinarian.



Testosterones:
The use of testosterone and testosterone-like products to reduce cycling in the cat is rarely done these days, the side effects often being deemed more unacceptable than those ofthe progesterone-type products.

Testosterones can make the female cat look and act more masculine (e.g. it may show increased muscle development, thickening of the skinon the back of the neck and clitoral enlargement) and cause it to develop many of the same masculine behavioural problems as the entire male animal(e.g. urine marking, mounting and aggression).

Testosterone products like mibolerone are considered to be quite toxic to cats. Testosterone-treated cats are prone to developing liver problems (some develop jaundice) and renal disease. They may also develop thyroid toxicity. Testosterone-treated catsare prone to developing oily, stinky-smelling skin and various skin conditions. Females can sometimes develop vaginitis and vaginal discharges as a result of testosteronetreatment. Treated animals are also more likely to develop fertility problems (subfertility issues) later on, particularly if they are given testosterone drugs after theirbreeding season has already started (testosterones, if given, should be given during theanestrous non-breeding-season (in winter) at least 30 days before the cat starts cycling).

Author's note - because testosterone-based products used in pets are similar tothose used illegally in human body-building competitions and competitive sports, theyare becoming more and more restricted for veterinary use because of the risk of themfalling into the wrong hands. This is another reason why progesterone has overtakentestosterone for pet estrus suppression.


Because of the risk of severe, life-threatening side effects, hormonally-induced heat suppression should only be used as a very last resort and, even then, only in animals that are intended tobe used as breeding animals later on (breeders need to be aware that significant loss of fertility canoccur with their use as well as uterine diseases like pyometron and mammary diseases like breastcancer). It is far safer to isolate your breeding cat from the males when it is in heat (season) or use one of the ovulation-induction techniques described in section 10d, than it is to try to artificially manipulate the female animal's reproductive cycleand keep heat suppressed using hormones. If breeding is not an aim for you, it is far better and safer todesex the female cat than it is to try to manipulate its reproductive cycle using hormones.



Remember again that not desexing the male animal in this situation will do nothing for his behaviour or health. He will still be inclined towards showing unfavourable entire-male behaviours (roaming, aggression, dominance, territory marking etc.) and he will still be prone toa range of testosterone-mediated health problems.

The best option is to get the male and female animals in your household desexed if theyare not breeding animals (you will be required to by law in certain states). There are important behavioural, medical and population-control benefits to be gainedby having each of the sexes desexed.


10d. Feline birth control method 4 - inducing ovulation to suppress feline estrus (heat).

As mentioned briefly in section 10a, female cats have a reproductive cycle that is seasonally polyestrous. Every time their breeding season (Spring through to Autumn) arrives, they alternate repeatedly between beingin heat (able to get pregnant) and being out of heat (the interestrus period - unable to get pregnant)for the entire breeding season. Now, as mentioned before, in a normal female cat, each estrus (heat) periodlasts for around 1-20 days (average of 3-10 days) and each interestrus (non-heat) period lasts foraround 2-20 days (average 8 days). That is ... if she is not mated during the receptive oestrus period.

If a female cat is mated during the estrus period, however, then one of three things might happen:

1) She might get pregnant - if this event occurs, the female cat will be pregnant and not-in-season for the approximately 63 days of pregnancy (termed the progesterone-dominant luteal phaseor diestrus period), for the approximately 6 weeks of lactation and for a further 7-20 days (up to 35 days) after weaning (termed the interestrus period), after which time the cat will come back into season again, ready to conceive another litter! NOTE - some queens will come back into season during lactation, approximately 10-15 days after birthing.

2) She might ovulate but not fall pregnant - female cats are induced ovulatorsmeaning that they mostly (not always) ovulate only when stimulated by the frictionof mating. If this no-conception, post-mating ovulation occurs, the female cat will go into a period of pseudopregnancy(called diestrous), whereby her body hormones will be similar to those of a pregnant cat (progesterone dominating) and her reproductive cycling will be suppressed, but no kittens will be growing in herwomb. In this situation, the cat will be not-in-season and not able to get pregnantfor the approximately 25-45 days of diestrous and for a further 7-20 days (up to 35 days) afterwards (the interestrous period), after which time the cat willcome back into season again, ready to conceive another litter! All in all, the pseudopregnant,cat will cease exhibiting any in-heat breeding behaviour for around 35-70 days (average 45 days).

3) She might not ovulate - female cats are induced ovulators, but not allmatings will make them ovulate (cats tend to ovulate more reliably with repeated matings andif mated later on, rather than earlier on, in the oestrus period). In these situations, the cat will not enter diestrous and a prolonged period of reproductive inactivity. Instead, she will finish her 1-20 day long (avg 7 days) oestrous period, enter a 2-20 day (avg 8 days)period of uterine inactivity (interestrous) and then return to season again, ready for mating.


So, how can this information be helpful?
As you can see from the information above, there is obviously less chance of a femalecat falling pregnant if she spends less time in receptive oestrous (heat) and more time in a non-receptive state such as diestrus or interestrus. Obviously, cats that get pregnant asa result of mating (option 1) spend the longest span of time non-receptive to male cats (up to about 125 days at a stretch), but obviously this is not the preferred option if the aim is to prevent female pregnancy!

Instead, what if option 2 could be used to our advantage? By inducing the cat in heatto ovulate without it getting pregnant, the subsequent inactive periods of interestrous and diestrous (non-receptivity) would be extended beyond that of a normal, non-ovulatory cycle, thereby reducing the chances of the female catfalling pregnant. The cat could be induced to ovulate, reducing the amount of annoyingin-heat female calling and the risks of the cat falling pregnant, all without the need for nasty hormonaldrugs (section 10c), which have severe side effects! Well, this is exactly what you can do.

There are two main ways in which ovulation can be induced in in-heat cats:
1) through the administration of ovulation-inducing medications and
2) through manual stimulation of the in-heat female cat's vagina (artificial mating).


Induction of ovulation using medications:
More reliable at inducing feline ovulation than manual stimulation, but with greatercosts (the cost of the medications), drugs such as hCG (human chorionic gonadotrophin)and GnRH (gonadotrophin releasing hormone) can be administered to in-heat cats toinduce ovulation and produce a pseudopregnant, diestrous state and a prolonged period ofnon-receptivity towards mating.

Dose rate 1: hCG is given at a dose rate of 250IU on days 1 and 2 of estrus.
Dose rate 2: GnRH is given at a dose rate of 25ug on days 1 and 2 of estrus.

Please note that the drug may have to be given every time the cat returns to estrus(approximately every 35-70 days - average 45 days - in the breeding season) if you want itto not show estrus and to not get pregnant for the entire breeding season (approx 9 months).


Induction of ovulation using manual stimulation of the vagina:
The theory behind manual stimulation of the cat's vagina is: if you rub a cotton tipor small glass rod back and forth within the female cat's vagina with enough friction to mimic the effects of natural mating, you may be able to induce the female to cat toovulate and the non-receptive diestrous state to occur. It sounds good in theory. The trouble is that there is no 100% reliable protocol available for manual stimulationof the feline vagina (necessitating that physical separation of the female from the malestill be imposed).

Although I can not guarantee that this technique will work in all cats to artificiallysuppress oestrous, this is the technique most commonly mentioned in all of the veterinary text books:
Probe the in-heat cat's vagina back and forth vigorously (mimicking mating activity) using the tipof a cotton bud (cotton tip) for about 2-5 seconds. Repeat this process 4-8 times moreat 5-20 minute intervals (this mimics the frequent, short mating intervals typicallyseen in the cat world - cats tend to mate often and for very short periods). The processcan be repeated over a couple of days.

Please note that this technique will not work in all female cats and that ovulation-inducing success has a lot to do with manual technique and the stage of estrus that the cat is in. Greater success is expected when a cat is manually stimulated over a couple of days(just like in the wild) and if it if stimulated later in the estrus cycle rather thanearlier on (i.e. once it has been calling for a few days and there has been enough timefor large, mature ovarian follicles to have developed on its ovaries).

Please note that, as with ovulation inducing medications, manual stimulationmay have to be applied every time the cat returns to oestrous (approximately every 35-70 days - average 45 days - in the breeding season) if you want the animalto not show signs of estrus and to not get pregnant for the entire breeding season (approx 9 months).

IMPORTANT - if you are thinking of using this manual technique, please ask your vet toshow you how to manually stimulate your female cat to ovulate before attemptingthis yourself. There is a chance of injuring your pet if you perform the procedureincorrectly.


10e. Feline birth control method 5 - feline vasectomy.
If all you desire is that your male cat not be able to breed with any females inside of or outside of your home, then feline vasectomy is an option for you. Vasectomy is the surgical removalof a section of the male animal's vas deferens or spermatic duct (the tube that takes the sperm fromthe testicle where it is made, to the lower reproductive tract regions of the prostate and urethra).Without this section of piping, the sperm can not reach the animal's urethra and penis andthe animal, therefore, can not get anything impregnated.

Vasectomy is certainly effective at stopping breeding and the passing on of defectivegenes to any offspring. It will not, however, do anything for that male animal's behaviour or health. Because the testicles are left intact during vasectomy, the animalwill still have plenty of testosterone in its body. He will still be inclined towards showing unfavourable male-animal behaviours (roaming, aggression, dominance, territory marking, mounting and copulating with females etc.) and he will still be prone to developing a range of testosterone-mediated health problems.

Author's note: vasectomy is not instantaneous. A vasectomised cat will still be fertileand capable of impregnating queens for 7 weeks following the procedure. The vasectomised cat should be evaluated by a vet prior to the reintroduction of the cat to any females toensure that his semen contains no sperm (i.e. that the procedure has been effective).


10f. Feline birth control method 6 - chemical castration - injecting sclerosing agents into the cat's testes and epididymides.
If all you desire is that your male cat not be able to breed with any females inside of or outside of your home, then chemical castration is an option for you.

During chemicalcastration, a sclerosing or scarring agent (e.g. chlorhexidine) is injected into the animal's testis and/or epididymus. This chemical induces a strong inflammatory reaction within the testicle and/orepididymus, resulting in severe scarring of the testis and epididymal sperm ducts such that theydo not permit the passage of sperm from the testicle to the lower reproductive tract regions of the prostate and urethra. The sperm can not reach the animal's urethra and penis andthe male animal, therefore, can not get anything impregnated. Additionally, the chemically-inducedinflammation of the testicle and epididymal tracts exposes the sperm (considered "foreign" cells to the male's immune system) to the animal's immune system. The immune system reacts aggressively against these sperm and all subsequently-made sperm cells, thereby rendering the animal effectively infertile (the immune system "kills off" all the sperm that get made in the future).

The main side effect of chemical castration is that the process of testicular and epididymal inflammationand scarring is very painful for the animal in the short term. The animal will be expected tohave hot, swollen, painful testicles and epididymi for quite a few days after the procedure has beenperformed. Some animals may suffer severe tissue reactions as a result of this process.

Chemical castration, like vasectomy, is certainly effective at stopping breeding and the passing on of defectivegenes to any offspring. It will not, however, do anything for that male animal's behaviour or health. Because the testicles are left intact during chemical castration, the animalwill still have plenty of testosterone in its body. He will still be inclined towards showing unfavourable male-animal behaviours (roaming, aggression, dominance, territory marking, urine spraying, mounting and copulating with females etc.) and he will still be prone to developing a range of testosterone-mediated health problems.

Author's note: chemical castration is not instantaneous. A chemically castrated cat will still be fertile and capable of impregnating female cats for around 140 days following the procedure. Additionally, only about 50% of chemically castrated cats will actually respond to the technique in that 140 days, making this a very hit-and-miss optionfor mating control. The chemically castrated cat should be evaluated by a vet prior to the reintroduction of the tom to any females to ensure that his semen contains no sperm (i.e. that the procedure has been effective).


10g. Anti-testosterone agents (e.g. Tardak, MPA-50, Ovarid) used to reduce testosterone-mediated behavioural problems in the tomcat.
All of the alternatives to surgical desexing mentioned thus far (i.e. sections 10a-10f)have pertained to feline birth control and the prevention of unwanted pregnancy. None of them have provided any solution to the castration-responsive behavioural problems that are caused or contributed to by the presence of too much testosterone in the animal's bloodstream. As mentioned previously, the problematic testosterone-mediated behavioural issues seen in the cat include: dominance, inter-male aggression and fighting, territorial aggression,territorial marking (urine spraying), territorial guarding, hypersexual behaviour, excessive libido, excessive sexual interest in females and so on.

Undesexed animals with significant testosterone-mediated behavioural and/or medical problems should, ideally, be neutered. Desexing is the best way to drop that animal's bloodtestosterone levels rapidly and permanently and thereby provide some relief and treatment for the medicaland/or behavioural issues at hand.

Owners who are unwilling to desex their male animals, however, even in the face of significant testosterone-mediated behavioural and/or medical problems, can make use of various alternative "anti-testosterone" medications as a way of treating ormanaging these conditions. These anti-testosterone medications are mainly reproductive hormone and reproductive-hormone-like chemicals; with progesterone and progesterone-derived compoundsthe most frequently used.

Similar to what was discussed in section 10c (hormonally induced estrus suppression in the queen),the problem with many of these hormonal testosterone-inhibiting progesterone solutions is that they can have potentially devastating, life-threatening and/or aesthetically displeasing side effectson the tom cat.

Progesterones and progesterone-derivatives:
Ovarid or megestrol acetate can be used for testosterone inhibition and treatment of testosterone-mediated behavioural and medical problems in the male cat.The progesterone and progesterone-derived drugs commonly used to temporarily or, with repeated use, permanently suppress testosterone production, testosterone action and testosterone-mediated medical andbehavioural problems in the male cat include: medroxyprogesterone acetate (MPA), megestrol acetate, proligestone and delmadinone. Common tradenames include: MPA-50, Ovarid and Tardak.

These progesterone drugs are thought to have several effects on the male reproductive system including the following:

  • They exert a negative feedback effect (suppressive effect) on testosterone production by the testicles. (They inhibit the production of GnRH or gonadotrophin releasing hormone: a hypothalamus-produced hormone that acts to stimulate the production of LH or luteinising hormone by the pituitary gland, which in turn acts to stimulate the testicles to produce testosterone.)
  • They inhibit the enzyme (5-alpha-reductase) responsible for converting the testosterone made by the testicles into its more active, potent form: 5-alpha-dihydrotestosterone (5-DHT).
  • They reduce or down-regulate testosterone-receptor numbers in certain tissues normally targeted by testosterone (e.g. the cells of the prostate), thereby providing the secreted testosterone molecules with fewer places to bind on to and exert their effect. Put simply, in order for testosterone to have any effect on a cell of the body (e.g. a prostate cell), it must be able to bind onto the surface of that cell first by attaching to a testosterone-receptor. If there are fewer testosterone-receptors available for testosterone molecules to attach on to, the testosterone can not exert its effect on those tissue cell/s.

At normal doses, these drugs have not been found to reduce male fertility or decrease spermnumber and nor do they appear to have any significant effect on male libido. Because of this,even though these drugs will reduce certain testosterone-mediated behavioural and medical problems,these drugs will not prevent a treated male animal from getting a female animalpregnant. At extremely high doses (higher than recommended), however, progesterones may adversely affectsperm production and motility, resulting in reduced fertility.

Tardak is commonly used to treat hypersexual behaviours and prostate disease and perineal masses in male dogs. It is also used in the male cat for similar reasons.Common side effects of progesterone use in the male cat are similar to those seen in thequeen and include: lethargy (sleepiness); increased appetite; weight gain and, occasionally, loss of hair or change in hair colour and shrinkage of the skin and subcutaneous tissues at the site of injection. Insulin resistance and diabetes mellitus may also be induced by long-term progesterone usage as can growth hormoneproblems like acromegaly. Progesterones can sometimes mimic the effect of corticosteroidsin the cat, resulting in adrenal gland suppression and a potentially life-threateninginability to make body corticosteroids ('stress-support' hormones) during periods of stress or illness (a condition known as Addison's disease or Addison's crisis).

Progesterone drugs are metabolised by the liver and should never be given to animalswith liver disease.

Some males treated with progesterone products have been found to develop mammary enlargement, mammary nodules and even nasty mammary tumours (breast cancer).

Author's note: of all of the progesterone products marketed for this purpose, delmadinone (tradenames include Tardak) and megestrol acetate (tradenames include Ovarid)are the more commonly used. They do have side effects (described above), but these are not too common provided the drug is used according to instructions and not for prolonged periods of time. The use of medroxyprogesterone acetate (MPA), although much safer in the male cat than in the female, is probablybetter left as a last resort (e.g. if Tardak or Ovarid fails to control problem male behaviours and so on). MPA stays in the body for many months and, because of this, poses a greater risk of producing severe side effects (e.g. diabetes) that are difficult to reverse (the drug, once-injected, can not be taken away). MPA does have an advantage in that a single injection of the compound will have aneffect on the testosterone-mediated disorder for many months (i.e. the owner doesnot have to keep dosing the animal).

Author's note: An anti-testosterone agent such as progesterone is never goingto be as effective at reducing or controlling testosterone-mediated behavioural andmedical conditions as neutering will. As long as the testicles remain in place, thedrug will only be able to temporarily hold-off these medical conditions and problembehaviours. These testosterone-induced problems will recur whenever the drug wears off, necessitating that the feline remain on repeated doses of medication for life.This is not only inconvenient and costly for the owner, but it also increases the risk thatthe animal will develop severe side effects as a result of the ongoing medication.


Final note - don't just rely on hormonal drugs or even neutering to solve all behaviouralproblems encountered in the male cat. As mentioned before, not all behavioural problemsseen in the cat are responsive to desexing or testosterone removal. Many behavioural problems arerelated to all manner of non-testosterone factors including: fear, anxiety, past experiences, owner reactions, environmental stimuli, hierarchical relationships between pets, poor trainingand so on. Some problems that seem to be sexual or testosterone-dependent may in factbe better treated with training, environmental modification, lifestyle changes, anti-anxiety drugs andanti-depressants, not desexing or reproductive hormones. Always seek the advice ofyour vet or an animal behaviouralist if your cat has a behavioural problem, particularlyone that desexing +/- progesterone has failed to curb.





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References and Suggested Readings:

1) Induced Abortion, Pregnancy Prevention and Termination, and Mismating. In Feldman EC and Nelson RW: Canine and Feline Endocrinology and Reproduction, 2nd ed. Sydney, 1996, WB Saunders Company.

2) Surgery of the Reproductive and Genital Systems. In Fossum TW, et al, editors: Small AnimalSurgery. Sydney, 1997, Mosby.

3) Canine Reproduction. In Daris W, editor: Compendium of AnimalReproduction, 5th ed. 1998, Intervet.

4) Kustritz MVR, Olson PN, Early Spey and Neuter. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

5) Verstegen J, Contraception and Pregnancy Termination. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

6) Kustritz MVR, Klausner JS, Prostatic Diseases. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

7) Davidson AP, Birth Control Alternatives. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

8) Johnson CA Disorders of the Estrous Cycle. In Nelson RW, Couto CG, editors: Small AnimalInternal Medicine, Sydney, 1998, Mosby.

9) Johnson CA Disorders of the Prostate Gland. In Nelson RW, Couto CG, editors: Small AnimalInternal Medicine, Sydney, 1998, Mosby.

10) The Pelvis and Reproductive Organs of the Carnivores. In Dyce KM, Sack WO, Wensing CJG editors: Textbook of VeterinaryAnatomy, 2nd ed. Sydney, 1996, WB Saunders Company.

11) Verstegen J, Feline Reproduction. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

12) Feline Reproduction. In Feldman EC and Nelson RW: Canine and Feline Endocrinology and Reproduction, 2nd ed. Sydney, 1996, WB Saunders Company.

13) DeNovo RC, Bright RM, Recto-anal Disease. In Ettinger SJ, Feldman EC, editors: Textbook of VeterinaryInternal Medicine, Sydney, 2000, WB Saunders Company.

14) Seksel K, The Cat With Aggression. In Rand J, Problem Based Feline Medicine. Sydney, 2007, Elsevier Saunders.

15) Seksel K, The Cat With Anxiety-related Behaviour problems. In Rand J, Problem Based Feline Medicine. Sydney, 2007, Elsevier Saunders.

16) Feline Reproduction. In Daris W, editor: Compendium of AnimalReproduction, 5th ed. 1998, Intervet.






Pet Informed is not in any way affiliated with any of the companies or clinics whose productsappear in images or information contained within this article. The images, taken by Pet Informed, are only used in order to illustrate certain points being made in the article.

Copyright December 7, 2008, www.pet-informed-veterinary-advice-online.com.
All rights reserved, protected under Australian copyright. No images or graphics on this Pet Informed website may be used without written permission of their owner, Dr. O'Meara.



MPA-50 and Neocort are registered trademarks of Ilium Veterinary Products.
Neotopic H Lotion is a registered trademark of Delvet Pty Ltd.
Covinan is a registered trademark of Intervet Australia.
Rimadyl is a registered trademark of Pfizer Animal Health.
Ovarid, Prolet and Tardak are registered trademarks of Jurox Pty Ltd.
Previcox is a registered trademark of Merial Australia Pty Ltd.
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Prescription Diet Feline i/d is a registered trademark of Hill's Pet Nutrition Pty Ltd.
Carprofen tablets are registered products of Apex.
Wound-Gard is a registered trademark of Allerderm.



Please note: the desexing information provided on this page contains general recommendations and medical advice only. The information provided is based on published information; relevant veterinary literature and publications and myown experience as a practicing veterinarian. The advice given is appropriate to the vast majority of pet owners, however, owners with pets should take it upon themselves to ask their own veterinarian for further advice on neutering. Owners with specific circumstances (breeding cats, showing cats, stud cats, breeding businesses, those seekingprosthetic implants, those whose cats have testosterone or hormone-mediated medical or behaviouralissues, those seeking to control estrus artificially in breeding/showing queens etc.) should ask their vet what the safest and most effective protocol is for their situation.

Any dose rates mentioned on these pages should be confirmed by a vet. Dosing rates for commondrugs are being changed and updated all the time (e.g. as new research comes in and as drugformulations change) and information here may not remain current for long. What's more, although we try very hard to maintain the accuracy of our information, typos and oversights do occur. Please check with your vet before dosing any pet any medication or drug.





Common misspellings and spelling variants: criptorchidism, criptorchid, cryptorkidism, cryptorkid, criptorkidism, criptorkid,cryptorkydism,cryptorkyd, criptorkydism, criptorkyd, cryptorchydism, cryptorchyd, criptorchydism, criptorchyd,testical, testecal, testacal, testucal, testecle, testacle, testucle, nuter, nutered, nutering, oestrous, oestrus,estrus, estrous, oestris, estris, diestrus, dioestrus, diestrous, dioestrous, diestris, dioestrous, interestrus, interoestrus, interestrous, interoestrous, interestris, interoestrous,anestrus, anoestrus, anestrous, anoestrous, anestris, anoestrous.

Alternative, slang synonyms for testicles: ball, balls, nut, nuts, goolies.

Alternative, including slang, synonyms for desexing: nut, nutting, nutted, the snip, the chop, castrate, castrating, castrationing, castration, gonadectomy, sterilisation, sterilising, sterilised, sterilization, sterilizing, sterilized, neutered, neutering, neuter, fix, fixed, fixing, desex, desexing.