Reproduction - When to Spay

It is pretty much universally agreed upon by vets that the best time to spay is BEFORE the first heat period. If a dog is spayed prior to the first heat, the odds of developing mammary cancer later in life are less than 1%. If spayed between the first and second heat periods the risk increases to about 8%. If spayed at any time after the second heat period, the risk of mammary cancer is about 25% in the dog (same as in an unspayed dog). There are no reasons not to spay prior to the first heat that I am aware of. A few dogs do develop incontinence from low estrogen levels after spaying but this does not appear to be affected much by the time the dog is spayed. Some dogs just develop this problem after spaying.

There are some health benefits for the female dog associated with spaying, including freedom from the complications of birthing puppies, reduced risk of mammary cancer and uterine infections. Uterine infections (pyometra) are a serious problem in dogs due to the way in which they cycle and can easily result in death. With the obvious benefit of spaying before the first heat and the lack of any problems that have been proven to occur as the result of spaying early, there does not appear to be much reason to wait until after a heat cycle.

Early Spay / Neuter

There is not a lot of data on the effects of spaying dogs and cats at younger ages than the "traditional" 6 months that has actually been published, at least that I am aware of. There are reports of two or three places studying the effects of early spay and neuter at the present time and I have seen references to data from these studies but am not aware of published data. I am only aware of one study of long term effects of spaying and neuter dogs at 7 months of age that followed the dogs for their entire lifetime. In this study, there were no problems attributable to spaying or neutering at this age other than a slight increase in the likelihood of estrogen dependent incontinence in female dogs. A lot of vets are spaying pets at 4 months of age pretty routinely now and humane organizations have been spaying animals in their care as early as 8 weeks for several years. Soon, there will be enough of these early spay and neuter patients and they will be old enough to figure out if there are long term effects. At present, no one is reporting any problems as far as I can tell.

Spay Verus Contraceptives