By Matthew Kearns, DVM
My last article (issue of April 30) describes the benefits of spaying or neutering dogs and cats for both medical and behavioral reasons. Overall, dogs and cats that are spayed and neutered live longer than unspayed and unneutered pets, so the question of “when” is usually before, or after puberty. Full disclosure is that there is far more published data on the advantages and disadvantages of spay/neuter in dogs than cats. This article also focuses on dogs and cats that were not spayed or neutered before adoption/rescue.
Studies have shown a significant reduction in euthanasia at shelters that employ an early (8 to 12 weeks old) spay/neuter program. Euthanasia is still the number one cause of death for pets in the United States so I want to make clear that I applaud shelters and rescues that employ juvenile spay/neuter programs.
The risk of certain types of cancer associated with the reproductive tract (mammary, ovarian, uterine, testicular) decreases significantly. Prostatic cancer remains unchanged neutered versus unneutered males but prostatic cancer is very uncommon in dogs or cats, so it is not really an issue. The risk of other types of cancer may actually increase in spayed/neutered purebred large to giant breed dog: specifically, osteosarcoma (bone cancer), splenic hemangiosarcoma, mast cell tumor, and bladder transitional cell carcinoma. These studies only evaluated risk in purebred dogs. Purebred breeds at higher risk include Golden Retrievers, Newfoundland, Irish Wolfhound, German Shepherd, American Staffordshire Terrier, and Rottweiler.
Non-cancerous developmental disorders in dogs such as hip dysplasia and cranial cruciate ligament rupture (the veterinary equivalent of anterior cruciate ligament) were in higher percentages in spayed and neutered patients. One should keep in mind that many of these studies compare dogs that were spayed or neutered before six months of age, which means before puberty.
Obesity and urinary incontinence (females only) are increased in spayed or neutered dogs. The studies that also covered obesity specifically also noted that owners that were obese tended to have obese dogs regardless of spay/neuter status.
In conclusion I have started to discuss with owners when to spay or neuter their pets. I still recommend spaying/neutering cats by, or before, six months of age. I don’t make recommendations for when to neuter dogs, but rather explore with owners pushing back the spay/neuter date until around a year of age to allow the dog to go through puberty (as long as there are no unwanted behaviors developing).
I do not recommend leaving dogs or cats intact throughout their lives unless they are breeding animals but that is just my opinion. I would recommend discussing the pros and cons with your own veterinarian before making a decision as to when the right time is for your pet.
Dr. Kearns practices veterinary medicine from his Port Jefferson office and is pictured with his son Matthew and his dog Jasmine. Have a question for the vet? Email it to [email protected] and see his answer in an upcoming column.