@Duncan: Do you have indoor cats, then? Because I was always taught they could start training to go outside around the age of 12 weeks, and then you could let them outside from 16 weeks. It makes sense to allow them out only after they have completely recovered from being neutered.
My vet still doesn’t encourage neutering after 16 weeks though… he says it’s important to neuter before the age of sexual maturity, because once those behaviours appear, they are unlikely to disappear again, even after neutering.
Having lived around a feral cat colony, I think you can definitely tell a good kitten from a dud really early on (I would say you can tell by the age of 5 weeks). You need to spend a lot of time with them though to find out. Late neuter cat is actually one of the best pets I’ve ever had… but a lot of his problems can be traced directly back to the fact that he wasn’t done early enough, and he became a fully mature male before the neuter. He also suffered a lot more during the neutering process than my other male kitten… he was miserable for about a week afterwards, whereas kitten was fine within less than a day.
icatcare says: “Traditionally male and female cats have often been neutered at six months of age, but this is after many cats reach sexual maturity and not based on any scientific rationale. For social, health and population control reasons, it is now recommended neutering should routinely take place at around 4 months of age.” [bold from the original website].
From the wiki: “Research in the 1960s proved that female animals permitted to reach sexual maturity prior to being spayed were susceptible to a higher risk of mammary cancer than those animals spayed prior to their first cycle. As a result, the recommendation was revised to perform surgeries just prior to the average anticipated age for the first cycle, 4 to 6 months for cats and 6 to 12 months for dogs.
Research from the 1990s and early 2000s suggests that it is safe, and maybe even desirable, to perform sterilization surgeries prior to sexual maturity and as early as 6 weeks old.
… The American Veterinary Medical Association issued a policy on Early-Age (Prepubertal) Spay/Neuter of Dogs and Cats in 1994. It was revised by the AVMA Executive Board April 1999 and April 2004 and now reads as follows:
The AVMA supports the concept of early (prepubertal, 8 to 16 weeks of age) spay/neuter in dogs and cats in an effort to reduce the number of unwanted animals of these species. Just as for other veterinary medical and surgical procedures, veterinarians should use their best medical judgment in deciding at what age spay/neuter should be performed on individual animals.
… Controlled studies and anecdotal reports have addressed many of these issues:
- Studies have found no significant difference in weight between cats and dogs sterilized between 6 and 14 weeks of age and those sterilized at an older age.
- Limbs of animals sterilized at a younger age tended to continue grow for a longer period of time than those of animals sterilized later (or not at all) resulting in slightly taller individuals. There is a higher occurrence (by 2 percentage points) of dogs sterilized at an early age with hip dysplasia; however, these dogs are three times less likely to be euthanized for the condition than dogs altered at an older age so the condition suffered by the dogs sterilized at an earlier age may be less severe.
- While external sexual organs of the animals who were sterilized at a younger age did not mature fully or to the same extent of those sterilized later, there was no significant negative impact on urinary tract health for most animals. Male cats sterilized at a younger age experienced a lower rate of urinary tract blockage than male cats sterilized at an older age. The one significant cause for concern in the studies was an increased incidence of urinary incontinence in female dogs leading to recommendations to delay spaying female dogs until 3 months of age when there is no concern about non-compliance with spay policies.
- There was no evidence of increased risk of infection for cats. Cats sterilized at a younger age showed a lower incidence of gingivitis (a condition which may be associated with immune suppression) than those sterilized at an older age. For dogs, there was a significant increase in the risk of parvovirus during the post-operative period for younger age patients but the researchers are not convinced that this translates into long term disposition to infection or is directly related to the nature of the procedure. It may be because dogs in shelters are at a higher risk for infectious disease and any surgery increases the risk of infection.
- While animals sterilized at younger ages were more prone to noise phobias and sexual behaviors, other behavioral issues such as separation anxiety, escaping behaviors, inappropriate elimination when frightened, and relinquishment were decreased in the population.