Overpopulation of companion animals is a serious problem in the United States, resulting in overcrowded animal shelters and widespread euthanasia. The severity of the situation stems from breeding operations and lack of awareness and action by animal owners/guardians to sterilize their pets and keep them separated from potential mates. The problem is exacerbated by ongoing relinquishment of companion animals, and the large populations of feral cats that continue to reproduce at alarming rates. This HRC primer summarizes the
available research regarding these and related issues.