AAHA Your pet Education Center Ask AAHA: Answers from the experts When should I spay or neuter my pet?
Cats: Female kittens can enter their first heat cycle as young as four months, but usually not until they are five or six months old. AAHA has endorsed the “Fix Felines by Five” initiative, which recommends sterilization of cats by five months of age. This recommendation prevents unwanted litters and greatly decreases mammary cancer risks in female cats as well as spraying/marking in male cats, but still allows kittens time to grow. Kittens sterilized at this age quickly bounce back from surgery.
Dogs: According to the AAHA Canine Life Stage Guidelines, small-breed dogs (under 45 pounds projected adult body weight) should be neutered at six months of age or spayed prior to the first heat (five to six months). Large-breed dogs (over 45 pounds projected adult body weight) should be neutered after growth stops, which usually is between 9 and 15 months of age. The decision on when to spay a large-breed female dog is based on many factors—your veterinarian can help narrow down the recommended window of 5 to 15 months depending on your dog’s disease risk and lifestyle.