Dog breeding is the practice of mating selected dogs with the intent to maintain or produce specific qualities and characteristics. When dogs reproduce without such human intervention, their offspring's characteristics are determined by natural selection, while "dog breeding" refers specifically to the artificial selection of dogs, in which dogs are intentionally bred by their owners. Breeding relies on the science of genetics, so the breeder with a knowledge of canine genetics, health, and the intended use for the dogs attempts to breed suitable dogs.
Programs which breed cats responsibly will not compromise a cat’s health for breeding purposes. Female cats should not be bred before they are 2 years of age, and they should only be bred every other year. Many legitimate breeding programs put a cap on the number of litters that a queen can produce, and they require medical check-ups for the queen before each and every litter.