One out of every four dogs brought into shelters is a purebred. Breed does not guarantee a dog free of medical or behavioral problems. For every puppy placed in a home, four others will remain homeless. The drive to mate is one of a cats strongest instincts. A female cat in heat will find a way out and attract unaltered males from around the neighborhood.
Cats have no taboos about mating with siblings or even their offspring.
Dogs and cats get fat and lazy from lack of exercise and from being overfed by their owners. A female cat will come in and out of heat approximately every two weeks until it is pregnant or spayed. A female cat nursing kittens may come into heat again and get pregnant before the last litter is weaned. Most die horrible deaths from disease, malnutrition, or some misadventure. The strong drive to mate will cause both male and female cats to roam, making them more susceptible to accidental death.