There is no easy answer to this question, just a mass of opinions and data. On the one hand various animal rescue agencies recommend early desexing to prevent unwanted litters; on the other there is strong research that suggests that early desexing is linked with a number of disorders particularly joint/hip related disorders. So which option is best???
This short article looks at some of the points to consider, and some research, regarding early desexing of dogs to help you make the right choice for your special pooch.
Probably one of the most cited reasons for early desexing of dogs is to prevent unwanted litters, ie population control. This is certainly advocated by the RSPCA in Australia as well as similar organisations in North America.
The case for early desexing for population control seems clear... if the dog doesn't have the reproductive organs then they can't reproduce. Easy! Well...
Actually whilst this is true for any particular animal, the studies on the population impact of early desexing are not so clear. To quote a literature review article (can be found here):
Surprisingly, empirical studies show no effects of desexing on population control in companion and shelter dogs despite desexing being consistently recommended in the literature.
How can this be? The research is pretty quiet on why this might be the case, but it is clear that even though it makes logical sense; it doesn't actually seem to work.
Reduced Risk of Cancer
Another regularly cited reason for the early desexing of dogs is a reduction in cancer risk, particularly mammary cancer in female dogs. A general search of the web will demonstrate this over and over; and it can be found as a main point in the RSPCA report noted above.
However the evidence isn't quite as clear cut as it would seem. A systematic review of the literature found "the evidence that neutering reduces the risk of mammary neoplasia, and the evidence that age at neutering has an effect, are judged to be weak and are not a sound basis for firm recommendations" (article here).
In fact, there is significant evidence of an increased cancer risk associated with early desexing particularly in relation to osteosarcoma, hemangiosarcoma, lymphoma, and prostrate cancer (article here).
This is probably the easiest factor to consider. There is a strong link between desexing and a lifespan increase in female dogs (article here).
There is very strong evidence that early desexing has a profound impact on likelihood of joint and/or hip disorders; particularly in larger breeds. The rate of increase is between 2-4 times more likely to develop these sorts of disorders for early desexed dogs, depending on which study you review. (article here)
Further, desexed animals are more prone to obesity which is also a significant risk factor for joint/hip disorders. Whilst the research above doesn't control for obesity; the results are still statistically significant without that control.
It would seem odd to include cultural/societal mores in an article on desexing, but it is important to note that whilst early desexing is generally recommended in Australia and America; this view isn't universal. In fact, in many European countries desexing is generally avoided and not promoted by animal health authorities (article here).
So Should I Desex?
YES! Unless you are intending on INTENTIONALLY breeding your dog, then desexing at some stage of their life is probably recommended.
WHEN is very much a personal question that you will need to answer, with the help of your Veterinarian. The fact is that there are many pros & cons to desexing your dog early as noted above. There also may be legislative controls such as those in South Australia.
What do we do?
In our case we run a Labrador Retriever stud so clearly our girls will not be desexed until after they have past their breeding life's. And even in those circumstances we will be choosing tubal ligation rather than complete gonadectomies. Why? Because we believe that these organs are more important to a dog's physiology than just reproduction; the hormones produced have other important roles to perform. As in fact they do in humans.
We are also, based on our reading of the research, generally recommending that new Pawents of our puppies delay desexing until after their first or second season for bitches; and after their first birthday for dogs. This is based the research that suggests that hip & elbow issues (a significant problem within the breed) are fewer with late desexing. We also recommend tubal ligation and vasectomy where possible, and where you can find a Vet who will perform them.
Of course this advice comes with the need for responsible ownership to prevent unwanted litters. You need to ensure that while your girl is in-season that she can't be gotten to by male dogs (keeping her inside is a GREAT idea); and that male dogs cannot wander. That is up to YOU.
So what do you think is best for your dog?