During puppy and kitten visits, we are commonly asked, “When is the best time to spay or neuter my pet?” While this is a great question, no magic number can determine when your furry pal should undergo a spay or neuter surgery. However, all pets should be sterilized, unless they are being bred responsibly to introduce desirable, healthy traits into their breed. 

Deciding on the best age to spay or neuter your pet is not always easy. Fortunately, the American Animal Hospital Association (AAHA) has set forth guidelines for the entire veterinary profession, and as an AAHA-accredited veterinary practice, our Haskell Valley Veterinary Clinic team adheres to AAHA’s standards. From there, our veterinarian can make a reasonable recommendation for an ideal sterilization age based on a multitude of factors.

AAHA guidelines for spaying and neutering cats and dogs

AAHA has provided guidelines for canine and feline spaying and neutering ages.

  • Cats — AAHA has endorsed the “Fix Felines by Five” initiative, which recommends that cats of both sexes be sterilized by 5 months of age. Although female kittens can enter their first heat cycle as young as 4 months of age, they more often are about 5 or 6 months old. Spaying a female kitten before her first heat cycle reduces her mammary cancer risk by 90%, while neutering a young male kitten minimizes the potential for unwanted spraying or marking that is common in intact male cats. Kittens who are spayed or neutered at this age quickly bounce back from surgery, and generally experience the greatest health and behavior benefits related to reproductive organs and hormones.
  • Dogs — AAHA has also produced recommendations based on a dog’s size and age, called the Canine Life Stage Guidelines. According to this set of guidelines, small-breed dogs (i.e., under 45 pounds at adulthood) should be neutered at 6 months of age, or spayed prior to the first heat cycle. Dogs in this size category receive the most health benefits by being sterilized by 5 to 6 months. A dog who is classified as a large-breed (i.e., more than 45 pounds at adulthood) should be neutered after growth stops, which is usually between 9 and 15 months of age. Deciding when to spay a large-breed female dog is more difficult, since multiple factors determine the best age to ensure adequate growth, while minimizing reproductive-related health risks. In general, a large-breed female dog should be spayed sometime between 5 and 15 months of age.

Why waiting to sterilize large-breed dogs is recommended

A decade ago, spaying and neutering all pets at an early age, regardless of their estimated adult size, was common practice. However, spaying and neutering large dogs at 4 months of age led to inadvertent health risks. Since fewer intact pets are strays and contributing to the pet overpopulation problem, waiting until these larger dogs are almost fully grown is now advised.

A study performed by the University of California, Davis (UC Davis) found that dogs weighing more than 44 pounds as adults were at a higher risk for one or more joint disorders if sterilized before 12 months of age. Dogs weighing up to 43 pounds had no increased risk for joint problems. Researchers examined common joint disorders, including hip dysplasia, elbow dysplasia, and cranial cruciate ligament tears. 

Another study performed by UC Davis looked at various breeds and their risk for certain cancers, including lymphoma, mast cell tumors, hemangiosarcoma, and osteosarcoma. This study examined 35 dog breeds and found vulnerability from sterilization varies greatly depending on breed. Some breeds sterilized at a young age are more likely to develop joint disease, while others are more prone to certain cancer types. The smaller breeds appeared to have no joint issues when spayed or neutered at any age, while a majority of the larger breeds tended to have joint disorders. One surprising exception was seen in two giant breeds—Great Danes and Irish wolfhounds—which showed no increased risk for joint disorders when spayed or neutered at any age.

Another important finding was that the dog’s gender sometimes made a difference in health risks after being spayed or neutered. For example, female Boston terriers spayed at the standard 6 months of age had no increased risk of joint disorders or cancers compared with intact dogs, but male Boston terriers neutered before a year of age had significantly increased risks.

With so many factors contributing to the best age for spaying or neutering a pet, deciding when to schedule your pet’s surgery can be difficult. However, your Haskell Valley Veterinary Clinic veterinarian can help you make the best decision for your furry pal, based on their lifestyle, size, breed, and health status.

Is your kitten or puppy reaching the age where they should be spayed or neutered? If so, let our Haskell Valley Veterinary Clinic team help you determine the best age for their surgery. Give us a call to schedule a consultation.