Spaying a dog or cat eliminates her heat cycle. Estrus lasts an average of six to twelve days, often twice a year, in dogs and an average of six to seven days, three or more times a year, in cats. Females in heat can cry incessantly, show nervous behavior, and attract unwanted male animals. Spaying and neutering makes pets less likely to bite. Unsterilized animals often exhibit more behavior and temperament problems than do those who have been spayed or neutered.
Neutering makes pets less likely to roam the neighborhood, run away, or get in fights.
Excuses, Myths . . . The truth is that most pets get fat and lazy because their owners feed them too much and don't give them enough exercise. It's better to have one litter first. Medical evidence indicates just the opposite. In fact, the evidence shows that females spayed before their first heat are typically healthier.