In my practice, clients will often bring me a kitten for examination and vaccination. Our protocol is typical for most veterinary practices: we vaccinate around 8 or 9 weeks of age, and again at 11 or 12 weeks of age, and once more at 15 or 16 weeks of age. Then, at 24 weeks of age, we neuter or spay.
This protocol of spaying and neutering around 6 months of age has been the professional standard for years. This posed a problem for shelters, however. If they adopted out a puppy or kitten, there was no way to ensure that the adopters would get the puppy or kitten neutered or spayed. Keeping the puppy or kitten at the shelter until it reached 6 months of age and then neutering or spaying wasn’t practical. The goal is to get the cats and dogs adopted out quickly, and keeping puppies and kittens for six months is costly and deprives families of the joy of watching the puppy and kitten grow up. Increasing the cost of adopting a cat or dog so that the adoption fee includes a voucher for a pre-paid spay or neuter has not been very effective. The national compliance rate of these programs is less than 40%.
The most effective way to ensure that animals adopted from shelters do not reproduce is to spay or neuter them before adoption. In fact, spaying and neutering can be performed in cats and dogs as young as 8 weeks of age. Early spay and neuter programs are supported by the AVMA and other well known veterinary organizations (the American Animal Hospital Associations, the British Small Animal Veterinary Association, and the Canadian Veterinary Medical Association). Early neutering and spaying, also called prepubertal gonadectomy, is defined as neutering by four months of age – typically between 6 and 14 weeks.
Pediatric spays and neuters tend to be easier, faster, and less expensive than they are in adult animals. The incidence of surgical complications is low due to the shorter surgery times, and anesthetic recovery and healing are shorter than in adults. The procedure is not without some controversy, however. This mainly has to do with potential long-term physiologic effects. Let’s look at the issues individually:
Obesity: A long-term study at Cornell that followed over 1800 dogs for up to 11 years concluded that male and female dogs that were neutered and spayed at an early age were less likely to become obese. Studies in cats have reached the same conclusion. Obesity is a multi-factorial problem that occurs regardless of the age at which a cat is spayed or neutered.
Stunted growth: there were some concerns that pediatric neutering would cause stunted growth in dogs, but this has proven false. In fact, pediatric neutering actually results in delayed closure of the growth plates. The long bones of dogs that undergo pediatric neutering are a little longer than those of animals neutered after six months of age. The growth is proportionate, though. The curve is the same. There’s really no clinical relevance to the delayed growth plate closure.
Hip dysplasia: Some vets have wondered whether pediatric spaying and neutering would result in an increased incidence of hip dysplasia. A study at Texas A&M showed no increase in incidence. A study at Cornell, however, showed a slight increase in incidence. So the jury is out.
Puppy vaginitis and peri-vulvar dermatitis: studies have shown that the age at the time of neutering has no influence on the incidence of these conditions in dogs.
Feline lower urinary tract disease: It was hypothesized that pediatric neutering of male kittens would decrease the diameter of the penile urethra in cats and would thus lead to increased incidence of urinary obstruction. This has been disproven. The diameter of the penile urethra in an adult male cat is the same regardless of whether a cat was neutered at 7 weeks of age vs. 7 months of age.
Urinary incontinence: this has been an issue in dogs. Many female dogs, when they get older, will develop urinary incontinence that responds to estrogen supplementation. The Cornell study concluded that there was a slightly greater risk of estrogen-responsive urinary incontinence in dogs spayed earlier than 12 weeks, while the Texas A&M study showed no difference.
Other studies have shown that male kittens that underwent early castration had a significantly lower incidence of abscesses, sexual behaviors, urine spraying, and aggression toward veterinarians. (Yay!) In both sexes, the occurrence of asthma, gingivitis and hyperactivity were also reduced. Shyness and hiding were the only behaviors found to increase in those animals neutered/spayed before 5 ½ months. Neutered cats are at increased risk of developing diabetes compared to their intact counterparts, but there’s no correlation between the timing of the neutering and the risk of developing diabetes.
So there you have it. Most of the concerns regarding the physiological effects of pediatric spaying and neutering are unfounded. As usual, most of the studies have been in dogs – cats once again getting the short end of the stick. (Fortunately, that is changing, thanks to the Morris Animal Foundation.) Bottom line: get your cat neutered or spayed. And don’t worry about the age at which it is performed.
"Spaying and Neutering"