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August 2014

This is a recent study done at the University of California (Davis). If you are thinking about neutering your dog, you might want to take a look.

Abstract

Our recent study on the effects of neutering (including spaying) in Golden Retrievers in markedly increasing the incidence of two joint disorders and three cancers prompted this study and a comparison of Golden and Labrador Retrievers.

Veterinary hospital records were examined over a 13-year period for the effects of neutering during specified age ranges: before 6 mo., and during 6–11 mo., year 1 or years 2 through 8. The joint disorders examined were hip dysplasia, cranial cruciate ligament tear and elbow dysplasia. The cancers examined were lymphosarcoma, hemangiosarcoma, mast cell tumor, and mammary cancer.

The results for the Golden Retriever were similar to the previous study, but there were notable differences between breeds. In Labrador Retrievers, where about 5 percent of gonadally intact males and females had one or more joint disorders, neutering at <6 mo. doubled the incidence of one or more joint disorders in both sexes. In male and female Golden Retrievers, with the same 5 percent rate of joint disorders in intact dogs, neutering at <6 mo. increased the incidence of a joint disorder to 4–5 times that of intact dogs.

The incidence of one or more cancers in female Labrador Retrievers increased slightly above the 3 percent level of intact females with neutering. In contrast, in female Golden Retrievers, with the same 3 percent rate of one or more cancers in intact females, neutering at all periods through 8 years of age increased the rate of at least one of the cancers by 3–4 times.

In male Golden and Labrador Retrievers neutering had relatively minor effects in increasing the occurrence of cancers. Comparisons of cancers in the two breeds suggest that the occurrence of cancers in female Golden Retrievers is a reflection of particular vulnerability to gonadal hormone removal.

Based on this information, what do you do when deciding on neutering time (or if to do it)?

The only conclusions we can make based on this is on Golden Retriever pups. The study showed that there are differences between breeds that confuse the decision.

Based on this study, it would seem that the earliest time to neuter or spay would be at one year, and not the traditional six months. There can be an argument to wait until they are two or three years of age.

The concern we have is that we are seeing these diseases. Joint disorders in large breed dogs (cruciate injuries top the list) are common. Here is a quote from the paper regarding Golden Retriever males:

The incidence of at least one joint disorder occurring in intact males was 5 percent. At neuter age <6 mo., at least one of the joint disorders occurred in 27 percent of the males, or five times the incidence of intact males (p<0.0001). At neuter age 6–11 mo., this incidence was 14 percent or almost three times that of intact males (p<0.005). In the 2–8 year neutering period there was a moderate rise in this measure to double that of intact males (p = 0.02).

And, we routinely see Golden Retrievers with cancer.

The incidence of females having at least one of the cancers where the incidence of cancers in intact females was just 3 percent. The increase in cancers over all the neuter periods ranged from 8 to 14 percent. Combining all of the neuter periods beyond 6 mo. (to have a larger data set for analyses), the elevated incidence level across all these neuter periods was significantly higher than that of intact females (p = 0.049). The results reveal that neutering through 8 years of age increases the risk of acquiring at least one of the cancers to a level 3–4 times that of leaving the female dog intact.

These results suggest that what we are doing is not working, so we need to look at doing it differently. What this study has done is brought up a lot of questions. Click on the link below to read the full piece.

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Web Link

Link for Full Neutering Study:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0102241