"Spaying" (females) and "neutering" (males) refer to the surgical sterilization of animals. Having a dog or cat spayed or neutered means that they cannot ever breed/reproduce.

During a spay surgery, the ovaries and uterus are surgically removed. During a neuter surgery, the testicles are removed.

Reasons to spay/neuter your dog or cat:
Spayed/neutered dogs and cats live longer, healthier lives.

Millions of healthy, temperamentally sound dogs and cats die in animal shelters every year simply because there are not enough responsible homes for all of them. Many more who are not taken to animal shelters are heartlessly abandoned to try to fend for themselves and they, too, end up not surviving.

Spaying/neutering reduces or eliminates the risk of mammary cancer, prostate problems, testicular cancer and in females, the complications which may arise during pregnancy or while giving birth or nursing a litter.
Spaying/neutering reduces a dog or cat's desire to roam - thereby reducing the risk that he or she will be hit by a car, injured in a fight, exposed to disease or perhaps come into contact with a human being who may seek to harm them.

Spaying/neutering reduces fighting and aggression.

Myth: Spaying/neutering makes dogs/cats fat.
Fact: Dogs and cats become overweight for the same reasons people do - too much food, too little exercise.

Myth:
My dog won't hunt, protect me, etc., if he/she is spayed or neutered.
Fact: Spaying or neutering a dog or cat will only eliminate the instinct to reproduce. The U.S. Customs Department aquires the majority of their dogs from animal shelters and these dogs are spayed/neutered. These dogs' drive to hunt and seek drugs, etc., is not affected by the animal being sterilized. An animal's instinct to protect loved ones is not at all diminished by spay/neuter.