Earlier this week, a new study from the folks at California-Davis was released discussing the potential health impact of spay/neuter -- and early spay/neuter. Cal-Davis has a long reputation as being a leader in veterinary medicine so the results of the study I think deserve to be taken seriously -- although with the caveat that I do believe there is a lot more research to be done in this arena.
The study looked exlusively at Golden Retrievers and separated the dogs into three groups:
1) Unaltered Golden Retrievers
2) Late-neutered Golden Retrievers (neutered after the age of 12 months)
3) Early-neutered Golden Retrievers (neutered before 12 months of age)
Based on their study, the neutered dogs had significantly greater risk of several conditions than their unaltered counterparts.
- Neutered males were at significantly greater risk of developing Hip Dysplasia (HD) Early neutered males were at more than double the risk as late neutered males. Early spayed females were at greater risk, but there was no difference in femails between late spayed females and intact females.
- While there were no occurrances of Cranial Cruciate Ligament Tears (CCL) in unaltered animals, or late-spayed females, there was significant occurrance in early altered males and females. The suty points to the role of gonadal hormones in controlling the closure of bone growth plates and that an atypical growth plate closure (resulting from the absence of gonadal hormones, may increase the chance of a clinically apparent joint disorder such as CCL or HD.
- Early-neutered males and females were more likely to develop Lymphosarcoma (the 3rd most popular form of cancer in dogs) than those that were neutered late or left unaltered.
- While cases of Hermangiosarcoma were rare in unalterd dogs and early-neutered dogs, there was a significant occurrance of the cancer in late-spayed females. Previous studies have also linked the spay of female dogs to Hermangiosacrcoma.
- Mast cell tumors were not present in unaltered females, but were significantly more common in late spayed females and present in early spayed females.
The study concludes that while the role of gonadal hormones in joint growth seems to have a causal role in Cranial Cruciate Ligament Tears and Hip Dysplasia, it is more complicated in certain cancers. The study is also quick to point out that impact may be very different in other breeds of dogs that have different growth patterns or health issues.
This study joins a growing list of studies about the impact of spay/neuter on the health of dogs, with previous studies also showing strong evidence for the neutering of males to increased occurrance of prostate cancer, and another study linking the early neutering of Rottweilers to increase the likelihood of osteosarcoma (bone cancer). Again, this one was linked to the importance of hormones in bone growth in large-breed dogs.
The impact of the research being done in this area may have a significant impact on the animal welfare community. Spay/neuter has become a very common practice in the US, and a primary form of animal population control for companion animals. However, if we really are into animal welfare, then the overall health of animals needs to be a consideration. Additionally, if we are to remain credible as organizations working to help people's animals, we have to be aware, and honest, about health impacts of spay/neuter. We also need to be exploring other alternatives to spay/neuter such as vasectomies and tubal ligations that may have the same positive impact on population control, without removing the important growth hormones.
This also further highlights that pushes for government mandates of spay/neuter are ill-advised as they may over-ride the information coming from the veterinary community about what is best for canine health.
The amount of research being done in this area is growing. And while there appear to be solutions that all parties can benefit from, we need to be aware of the research so that we are knowledgable, aware of what I think will be the growing change in how we view spay/neuter in this country, and prepared to change our current practices based on the most current information available. Remaining ignorant on this topic, or hiding our heads in the sand will not change it or make it go away.
The full study is here.