Every male dog has the capacity to father hundreds of puppies.
Often, intact dogs are allowed to wander at will, and they manage to find females in season with whom they mate. Unwanted puppies are born, many which are abandoned or euthanized. The ranks of unwanted pets include purebreds, approximately 30 percent. Birth control for animals is a necessity and a kindness. A sexually active dog can become infected with, and in turn become a carrier of, brucellosis.