Pets are homeless everywhere
In every community, in every state, there are homeless animals. In the U.S., there are an estimated 6-8 million homeless animals entering animal shelters every year. Barely half of these animals are adopted. Tragically, the rest are euthanized. These are healthy, sweet pets who would have made great companions.
The number of homeless animals varies by state—in some states there are as many as 300,000 homeless animals euthanized in animal shelters every year. These are not the offspring of homeless "street" animals—these are the puppies and kittens of cherished family pets and even purebreds.
Many people are surprised to learn that nationwide, more than 2.7 million healthy, adoptable cats and dogs are euthanized in shelters annually. Spay/neuter is the only permanent, 100 percent effective method of birth control for dogs and cats.
Your pet's health
A USA Today (May 7, 2013) article cites that pets who live in the states with the highest rates of spaying/neutering also live the longest. According to the report, neutered male dogs live 18% longer than un-neutered male dogs and spayed female dogs live 23% longer than unspayed female dogs. The report goes on to add that in Mississippi, the lowest-ranking state for pet longevity, 44% of the dogs are not neutered or spayed.
Part of the reduced lifespan of unaltered pets can be attributed to their increased urge to roam, exposing them to fights with other animals, getting struck by cars, and other mishaps.
Another contributor to the increased longevity of altered pets involves the reduced risk of certain types of cancers. Unspayed female cats and dogs have a far greater chance of developing pyrometra (a fatal uterine infection), uterine cancer, and other cancers of the reproductive system.
Medical evidence indicates that females spayed before their first heat are typically healthier. (Many veterinarians now sterilize dogs and cats as young as eight weeks of age.)
Male pets who are neutered eliminate their chances of getting testicular cancer, and it is thought they they have lowered rates of prostate cancer, as well.