How Old Does a Kitty Have to Be to Get Fixed?

The age at which kittens and cats can be fixed, spayed, neutered or altered has been the subject of controversy among and between veterinarians, shelter professionals and pet owners since the 1970s. Complications, advantages and disadvantages exist with any surgical procedure, and each cat should be evaluated on an individual basis. Talk with your veterinarian about the benefits and risks for spay and neuter surgery for your cat or kitten.

Many veterinarians recommend to cat owners that spaying or neutering their cats should be part of a general health care plan, but controversy exists about when to perform the surgery. Veterinarians traditionally advised people that the optimal age for the procedure was about six months old, despite a lack of scientific data establishing an ideal age for the surgery. Dr. Dave Sweeney, a proponent and veterinary practitioner of early pediatric spaying and neutering -- especially for shelter kittens -- believes pet owners should have their young, unfixed kittens spayed or neutered when they are no older than 16 to 18 weeks old. Kittens enter puberty at around four months old, so waiting any longer increases the risk of an unplanned, unwanted pregnancy, he says.

Shelters and rescue facilities usually spay and neuter kittens as young as two months old and weighing at least 2 lbs. The American Veterinary Medical Association supports pediatric spaying and neutering for 8- to 16-week-old kittens, because the result is a reduction in unwanted and homeless felines. Spaying a kitten before her first heat may prevent mammary gland tumors in adulthood. Kittens reach puberty and go into heat at around four months old, so waiting until a female cat is six months old increases the risk of accidental pregnancy and of mammary gland cancer, according to Dr. Lila Miller.

Some veterinarians consider early spaying or neutering of kittens unsafe. Those opposed to performing the procedure before kittens reach puberty argue that doing so could cause stunted growth, obesity, behavioral changes, urinary incontinence or bone fragility. According to Dr. Margaret V. Root Kustritz, most of these fears are unfounded and “no correlation has been found between the age a cat is altered and the final body weight and amount of body fat” or the incidence of bone fractures. Dr. Lila Miller of the ASPCA reports that “researchers at Texas A&M University found no increase in cats’ physical or behavioral problems" at least three years postoperatively.

Cats who are not altered are seven times more likely than spayed cats to develop mammary gland tumors when they are mature. Ninety percent of mammary gland tumors in cats are malignant, but “spaying at an early age, especially before the first estrus or heat, has a sparing effect and reduces the risk,” according to The Merck Veterinary Manual. Unpleasant and potentially dangerous behaviors of intact male cats, including spraying, fighting and wandering, can make them difficult to keep as pets. Neutering male cats protects overall health and is beneficial, especially when the neutering takes place before the cat begin spraying. Most people notice positive changes in their male cats' behavior after neutering.