What is the best age to neuter or spay your dog?

In the United States, it is now common practice for all dogs and cats not intended for breeding purposes to be spayed (oophorectomy) or neutered (neutered). In fact, 78% of dog-owned households have spayed or neutered their companion dogs according to the 2019-2020 National Pet Owners Survey conducted by the American Pet Products Association.

This semi-routine practice was the result of veterinarians and the animal shelter community working together to reduce the number of unwanted animals that would be euthanized. Currently, Statista estimates that 6.5 million animals enter US animal shelters each year. Of this number, it is estimated that 1.5 million died euthanized. Although euthanasia has declined over the past decade or so, there is still a very strong case for routine/neutral sterilization of pet cats and dogs.

Understand the basics

Often, spaying and neutering is done at a very young age of pets, at four to six months of age. However, studies have shown that this may not be the best age to spay or neuter your dog. The relationship between sex hormones and canine health was not well studied and understood decades ago when the early spay/neuter campaigns began. Today, we discover that some of these decisions may have affected the health of some dogs.

Research conducted by the University of California-Davis revealed that for some dog breeds, neutering and spaying may be associated with an increased risk of certain health conditions such as joint disorders including hip or elbow dysplasia, cruciate or cranial lacerations, and some types of cancer, such as lymphoma. Mast cell tumor, hemangiosarcoma, and osteosarcoma. The research conclusions are not surprising. Sex hormones are important in the growth of any animal. We know that they affect psychological development as well as the musculoskeletal, cardiovascular and immune systems.

Interestingly, different breeds and dogs of different sizes mature at different ages, which means that early spaying/neutering may not be bad for all dogs. The wide margin for maturation of dogs varies greatly, with toy breed dogs maturing sexually as early as six to nine months of age, while large and giant breeds may mature as late as 16 to 18 months of age. The final conclusion is that in general, larger breeds are more likely to be at risk in future health conditions than small or toy dog ​​breeds for early spaying or neutering since they mature at a later age.

Irish red and white laying on the lawn with a stuffed toy.

Your turn as the owner

The American Veterinary Medical Association promotes “the professional judgment of the veterinarian in developing an informed, case-by-case evaluation of each individual patient, taking into account all potential risks and benefits of spaying/neutering.”

My opinion on this topic is that the best age for spaying or neutering should not be the standard “six months of age” response that many vets have used as a guideline over the years, but rather tailored to each individual dog, especially if the dog is a large or giant breed . If you have a purebred dog, you should also speak with your breeder, who may be able to provide insight. Next, you should have a discussion with your veterinarian based on your dog’s breed or breed type, gender, and potential future medical concerns.

Six to nine months of age may be appropriate for neutering or spaying a toy breed puppy or small breed puppy but a larger or giant breed may need to wait until they are near or over 12-18 months of age. It is also important to understand that often, the earlier these procedures are performed, the easier the surgeries will be for the vet and the patient’s recovery. The only rule I would recommend is not to intentionally spay a female dog while they are going through their heat cycle as this can exacerbate excessive bleeding.


Spaying and neutering pets remains an important part of efforts to reduce the number of unwanted animals and unnecessary euthanasia in this country. When considering whether to spay or neuter your dog, with today’s information about the potential effects of age at the time of surgery on their future health, it is ideal to have a detailed discussion with your veterinarian to determine what is best for your dog.

Leave a Comment