They require a minimum amount of space for each dog, shelter, a feeding and veterinary care program, fresh water every 24 hours, proper drainage of the kennel, and appropriate sanitary procedures to assure cleanliness. USDA licensed more than 4600 animal dealers, more than 3000 of them dealing solely in wholsale distribution of dogs and cats, in 1992. It's easy to say that John Jones or Mary Smith runs a puppy mill or that pet store puppies come from puppy mills, but the label is tossed about so frequently and with so little regard for accuracy that each prospective dog owner should ascertain for himself whether or not he wishes to buy a dog from John Jones, Mary Smith, a pet store, or a hobby breeder. The dogs may be healthy or not and the kennel may be clean or not. The dogs are probably not screened for genetic diseases, and the breeding stock is probably not selected for resemblance to the breed standard or for good temperament.
Most commercial breeders sell their puppies to pet stores or to brokers who sell to pet stores.
Brokers ship puppies by the crate-load on airlines or by truckload throughout the country. Brokers must be licensed by USDA and must abide by the shipping regulations in the Animal Welfare Act. A dog owner whose pet either gets bred by accident or who breeds on purpose for a variety of reasons. This breeder is usually ignorant of the breed standard, genetics, behavior, and good health practices. A backyard breeder can very easily become a commercial breeder or a puppy mill.