The optimal age to spay or neuter a cat is before it reaches 5 months of age. For owned cats, the optimal age would be 4 to 5 months, while for cats in shelters, the optimal age could be as early as 8 weeks. Kittens can be spayed or neutered at about four months old. However, there are different opinions among veterinarians about the best time to spay or neuter a cat. Some recommend early or pediatric spay/neuter, which is done at six to eight weeks of age, while others recommend standard spay and neuter at five to six months. Waiting until after the first heat, somewhere between eight to twelve months of age, is another option.

Current scientific evidence shows no medical or behavioral reasons to delay spaying/neutering of cats past 5 months of age, and there are population and health benefits to early spay/neuter. Early spay/neuter can eliminate the behaviors displayed when in heat as well as unwanted pregnancies. Neutering male cats before 5 months of age can substantially reduce or eliminate male territorial marking, fighting, and roaming.

It is important to consult with a veterinarian to determine the best time to spay or neuter a cat, as each pet is unique and may have different needs.