A puppy mill is a breeder who produces puppies with no breeding program, little attention to puppy placement, and poor health and socialization practices. Conditions in puppy mills are generally substandard and may be deplorable, and puppies and adult dogs may be malnourished, sickly, and of poor temperament. .

A puppy mill breed dogs for the sole purpose of maximum profit. The phrase comes

 from World War II, when the US Agriculture Department encouraged struggling farmers to raise puppies as an alternative "crop”. Retail pet stores opened across the US in response to the growing supply of pups, paving the way for mass puppy production. Novice puppy farmers, however, often launched their ventures with little money and even less knowledge of canine husbandry. To this day, the folks, also known as puppy-millers, who run these disgusting businesses do not take proper care of their animals and do not take genetic defects or hereditary disorders into consideration. They just don’t care. They just want to make a buck.

There are different degrees of "puppy mills". The breeding mothers, called bitches, live a horrendous life breeding one litter after another with no socialization at all. At the age of about six or seven, or when they cannot produce anymore, they are often killed since they are now a financial burden.

Most dogs are confined in tiny, cramped, wired cages on top of each other, living in unsanitary conditions with little or no veterinary care. There are some puppy-millers who offer a tad of veterinary care and try to keep the kennels clean but if it walks like a duck and talk likes a duck then pretty much 99% of the time it is a duck!

Puppy mills produce dogs that are of poor quality and, more often than not, sickly. Puppy mill pups are stripped from their mothers as young as six weeks and transported by trucks and airplanes when their immune system is low. With this come illnesses such as the deadly parvo and distemper. A pup with distemper or parvo is not a good way to start a life. You begin with vet bills and no guarantee that your new pup will even live.