It helps to reduce companion animal overpopulation. Most countries have a surplus of companion animals and are forced to euthanize or disregard their great suffering. The surplus is in the millions in the United States. Cats are 45 times as prolific as humans, dogs are 15 times! They do not need our help to expand their numbers; they need our help to reduce them.
Sterilizing your cat or dog will increase his/her chance of a longer and healthier life: for dogs, an average of 1 to 3 years; for cats, 3 to 5 years. Altered animals have a very low to no risk of mammary gland tumors/cancer, prostate cancer, perianal tumors, pyometria, and uterine, ovarian and testicular cancers.
Sterilizing your cat or dog makes him/her a better pet, reduces his/ her urge to roam and decreases the risk of contracting diseases or getting hurt as they roam. Intact male cats living outside have been shown to live on average less than two years. Feline Immunodeficiency Syndrome is spread by bites and intact cats fight a great deal more than altered cats. Surveys indicate that as many as 85% of dogs hit by cars are unaltered.