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Friday, 1 March 2013

Controversial new study says neutering your dogs can triple their risk of cancer or joint disorders -

Controversial new study says neutering your dogs can triple their risk of cancer or joint disorders - 

Neutering dogs can double or triple their risk of cancer or joint disorders, a controversial new study reveals.
In fact, the risk of lymphatic cancer (lymphosarcoma) was three times more common in early neutered males than non-neutered males. And cancer of the blood vessel walls (hemangiosarcoma) was quadrupled in late-neutered females than non-neutered.
The study also found neutering male and female golden retrievers produced weak protection against mammary or prostate cancer, contrary to popular belief.
Researchers at the University of California Davis studied 759 golden retrievers registered at their Veterinary Medical Teaching Hospital.
Golden retrievers are popular and common but also more vulnerable to certain cancers and joint disorders than other breeds, the study pointed out.
The results can only be extrapolated to other breeds to a certain extent, lead researcher Dr. Benjamin Hart told the Toronto Star.
What’s a dog owner to do?
“Two things. Certainly avoid early neutering, before a year. This takes away the developmental effect of gonal hormones,” said Hart, a veterinary professor and animal behaviourist at UCD.
“A golden retriever is not much of a behaviour (aggressive) dog. Why not just not neuter unless you have to? There is nothing to be gained by neutering a male early.”
“If it’s females, don’t spay too early. Wait until she’s a year or 13 months so you can get past the knee and elbow and hip dysplasia problems. That’s early enough in goldens.”
Hart has been debating his results — since they were published in PLOSone — with staff at animal shelters, which often forbid adoptions of unneutered animals regardless of age.
“I don’t want to adopt a dog if the neutering doubles or triples the chance of a hip disorder,” Hart said. “I can be a responsible pet owner. People should have the dignity of deciding for their pets.”
He advocated a vasectomy or tubal tying for dogs before a shelter adoption instead of neutering.
“These operations are much less expensive and less traumatic for the dogs. The weird thing is we don’t teach these simple operations yet in vet schools, but shelter vets could learn it in an afternoon wet lab.”
The Ontario SPCA chief veterinary officer disputed the findings.
“There is no clear or obvious link between these diseases and neutering, we can say there is no clear nor proven causal relationship. There were various issues with this study such as the lack of numbers of cases for comparison, lack of discussion of limitations and potential bias, and therefore we would conclude very little from this study,” said Dr. Magdalena Smrdelj.
“We recommend spay/neuter for all animals, preferably at early age.”
The study is the first to examine the effects of early (before one year) and late neutering on several types of joint disorders and cancers in one breed of dog, the report said.
Hart made it clear that even with the strong evidence in the study, the numbers of golden retrievers that developed cancer or joint disorders were still low.
For example, while the number of early-neutered males diagnosed with lymphosarcoma was tripled, it was still only 10 per cent of the golden retrievers studied.
And while cases of hemangiosarcoma in late-neutered females quadrupled, compared with early-neutered or unspayed females, it was still only 8 per cent.
“You have to remember most of the dogs did not get cancer. It’s a matter of risk. Most people don’t want to double or triple the risk.”
The UCD researchers next intend to study the effects on Labrador retrievers and then German shepherds.


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