1) Spaying or neutering increases your cat's or dog's chances for a longer, healthier life.
Spaying your pet before her first estrous cycle (that is, before she reaches sexual maturity) greatly reduces her chances of developing breast cancer and completely eliminates the threat of uterine and ovarian cancer and uterine infection, which are common occurrences in unaltered females.
Neutering your male cat or dog prevents testicular tumors and may prevent prostate problems. Neutering also decreases the possibility of perianal tumors and hernias, which are commonly observed in older, unaltered dogs. Because neutered pets are less likely to roam, the threat of abscesses caused by bites and diseases transmitted by fighting are greatly reduced.
2) An altered cat or dog is a better pet for your family.
Males neutered early in life are less aggressive toward other males and are not distracted by females in heat. Therefore, a neutered male will be less tempted to leave your property and cross that dangerous highway searching for a mate. Neutered males also are less likely to mark every one of your (or your neighbor's) expensive shrubs with his urine as well as inside the house.
Spaying your female pet eliminates the problem of stray males camping in your yard and decreases her desire to roam and breed.
3) No family wants to cope with an unwanted pregnancy.
Spaying prevents your pet from giving birth to unwanted puppies or kittens. A cat and her litter can theoretically produce 420,00 kittens in 7 years.
4) You are helping to alleviate the cat overpopulation problem.
Each year, millions of unwanted cats and dogs are euthanized at shelters across the country. Many orphans are the result of accidental breeding by free-roaming, unaltered pets. The more pets spayed or neutered, the fewer cats will have to be destroyed.