There has long been discussion around the most appropriate age for dogs to be neutered.
Certain dog breeds have been shown to have an elevated risk of developing cancers and/or joint disorders when neutered at an early age. However, that risk had only been assessed across a very limited number of breeds. A new study published by researchers from the School of Veterinary Medicine at University of California, USA, sheds new light on this topic. ‘Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence’, a 10 year study of 35 dog breeds, has uncovered a large disparity of risk of joint problems and cancer amongst different breeds.
The joint disorders include hip dysplasia, cranial cruciate ligament tear or rupture, and elbow dysplasia. The cancers include lymphoma, mast cell tumour, hemangiosarcoma, and osteosarcoma.
The researchers analysed data from thousands of dogs examined at the University of California Veterinary Medical Teaching Hospital to try to determine whether neutering, the age of neutering, or differences in sex affected certain cancers and joint disorders amongst different breeds of dog.
In most of the breeds examined, the risk of developing problems was not affected by the age of neutering. Not surprisingly researchers found that vulnerability to joint disorders was mostly related to body size.
Small-dog breeds seemed to have no increased risks of joint disorder while a majority of the larger breeds tended to have joint disorders. Interestingly, an exception to this was among the two giant breed, great Danes and Irish wolfhounds, which showed no increased risk to joint disorders when neutered at any age.
The researchers also found the occurrence of cancers in smaller dogs was low, whether neutered or kept intact. In fact, only two small breeds, Boston Terrier and Shih Tzu, showed a significant increase in cancers associated with neutering.
In most cases, a dog’s owner can safely choose the age of neutering without increasing the risks of joint disorders or cancers.
However, of the 35 breeds studied, 9 breeds showed increased risks and were recommended to be neutered after 23 months of age. For males these breeds included Bernese Mountain Dog, Boxer, German Shepherd, Irish Wolfhound, Standard Poodle. For females the breeds included Boxer, Cocker Spaniel, Doberman Pinscher, German Shepherd, Shetland Sheepdog and Shi Tzu.
To assist pet owners and veterinarians in deciding the appropriate age of neutering a specific dog, guidelines are laid out for neutering ages on a breed-by-breed and sex basis. The study suggests that dog owners should carefully consider when and if they should have their dog neutered.