As a veterinarian, the recommendation to spay/neuter pets has always been very simple – do it and the sooner the better. Spaying and neutering involves the surgical removal of a pet’s ovaries and uterus (spay) or testicles (neuter). We have all been taught that this procedure helps thwart many health, behavioral, and population problems. However, recent research is refuting the health benefits of spaying and neutering. Now, making the decision whether or not and when to spay/neuter is much more difficult. (See the research in a recent post)
There are flaws in every one of these studies and no single piece of research should ever be looked at as conclusively proving anything. On the other hand, the weight of research now indicates that sterilizing pets is not as innocuous as most people (and vets) think. It turns out that when you upset the intricate balance of the endocrine system, by removing the source of sex hormones, bad things can happen.
We have known for decades that sterilizing immature pets delays the closure of their bones’ growth plates, causing the bones of the legs to grow abnormally long. The thing we’re just now realizing is that extra-long bones can throw off the biomechanics of the legs, apparently leading to an increased risk of ACL ruptures and hip dysplasia. It is also becoming apparent that the upsurge in cancer we have been seeing in pets may, in part, be due to us inadvertently screwing up their hormonal balance.
So what’s the answer? One size does not fit all. In general I recommend delaying spaying and neutering until the pet is 1 – 2 years old, if and only if you can handle the responsibility of keeping your pet from reproducing. This will give the body the benefit of fully maturing before the hormones are removed. Of course if the mess of a female in heat or the annoyance of unwanted male behavior is too much to handle, then by all means, spay/neuter your pet earlier.