(the study) http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0055937
(the study) http://tinyurl.com/ccha8s4
What is even more thought provoking is that this is NOT actually early spay/neuter as it is currently defined and practiced in the US. The "early" is before a year of age, whereas "old school" norm was 6 months. Early or even "normal" speutering is now at weaning or 2 to 3 months of age, according to many vets.
Be careful of studies - this is one of my pet peeves.
This is not a double blind study that has a minimum of bias, but one that is essentially a survey of a population of dogs that showed up at one clinic with a problem.
It doesn't include a comparison population of healthy dogs and whether they are spayed or neutered early. If you took 566 healthy golden retrievers, and did the same analysis, what would the breakdown be? We need to know that.
Also, there are mixed results here. It isn't that early spay/neuter is all bad. For example, if you look at females, leaving a female intact doubles the chance of hip dysplasia compared to neutering late. Also, early spay actually appears to reduce the incidence of HSA and MCT by half. So does this mean that early spay helps reduce certain kinds of cancer? This study doesn't provide that answer. Why?
It doesn't break down the unhealthy dogs in terms of other potential factors such as origin (was this a casually bred or shelter dog or one that came from good health clearances) or whether there are any socioeconomic factors (does the cost of their clinic influence the economic status of people that bring their dogs there)... It also includes all spay/neuter under 12 months as "early". Since most pets are spayed/neutered "early" and more breeding/show dogs are spayed/neutered late or left intact, could this be influencing the study because pets are often poorly bred and more likely to have health problems to start with? What if you broke down "early" into less than 3 months, 3-6, 6-9, 9-12? There are many other factors that skew data in strange ways. All of the conclusions in this study really are speculative.
It also doesn't factor in for females the risks of getting pregnant at first heat, whelping at a young age, and the subsequent issues of unwanted puppies being born.
More study needs to be done... I want to see a controlled double blind study that really breaks down the risks and benefits of when a dog is spayed/neutered. Or at the very least, let's see when the healthy dogs are spayed/neutered. It's so important - we need to know!
People are going to neuter and spay. I would like to see a study that shows a reduction in cancers and orthopedic issues correlated with when the animals are neutered. . . ie would you see a 10% reduction if you wait until the animal is a year, a 15% reduction if you wait until he is two. That would be a good guide.
