To maximise profits, puppy mills often resort to poor breeding practices and inbreeding (the practice of breeding two dogs who are related to each other). This can result in genetic consequences for the puppies, including serious inherited conditions, deformities, heart defects, reduced immunity and temperament issues.
Coupled with the poor living conditions and often a lack of routine veterinary care, the dogs in puppy mills are exposed to diseases, infections, skin problems, injuries, psychological and socialisation issues.
The breeding dogs have it worse. Treated like puppy-producing machines, they are forced to breed very often with little rest, resulting in great physical and mental strain. Many of these breeding dogs stay in small cages their whole life, except when they are mating. When they are unable to produce any more puppies, they are abandoned or put to sleep.