Risks of Spaying & Neutering Too Early

Veterinarians often recommend spaying or neutering of puppies early to prevent sex hormone-related cancers (mammary, ovarian, testicular and prostate cancer) and pyometra (a serious uterine infection), as well as for population control. This advice must be weighed against the serious risks associated with spaying or neutering puppies too early.

Testosterone and estrogen from the reproductive organs are crucial for proper growth and development of bones, muscles, joints, and several body systems including the urinary tract and cardiovascular system. Early removal of these hormones can cause problems in growth and development, joints, bones, and muscles.

Studies show that early spaying/neutering significantly increases the risk of several joint disorders including CCL tears and hip dysplasia. The risk is increased because the dog's long bones continue to grow without the normal hormone-mediated signals to stop growing at the appropriate time, leading to disproportionate bone growth and increased joint stress.

Neutered male dogs have 2–4 times the risk of developing prostate cancer than intact dogs. Female dogs spayed before their first heat cycle have increased risk of urinary incontinence — early spaying increases this risk by as much as 5–20 times. Behavioral issues can also be increased due to early spaying/neutering, as testosterone and estrogen play important roles in brain development.

Most veterinarians now recommend waiting until a dog is at least 12–18 months old before performing spay/neuter surgery. For toy breeds like Cavaliers, discuss timing with your vet based on your individual dog's health and circumstances.