A puppy mill is dog breeder that cares about profit over the well-being of dogs. Puppy mills are disgusting, the dogs are usually in stacked wire cages where they can get injuries on their paws and legs. Puppy mills treat dogs like products, they live in overcrowded and unsanitary conditions without adequate veterinary care, socialization, or even food and water. Because of this they can develop diseases and behavioral issues.
I actually believe that my dog (toy poodle) was from a puppy mill we had no idea because we didn’t get to see where she was coming from we just found a website and ordered her online (very expensive too). She came from Missouri and apparently Missouri is the leading puppy mill state in the country! When she arrived at the airport she had worms, and kennel cough (my other dog got kennel cough from her too). She is now perfectly healthy but this just goes to show that puppy mills do not take care of the dogs, they only care about the profit they make and breeding as much dogs as possible to sell the puppies.
You definitely need to do research before buying a dog anywhere (we should have). Purchasing a puppy for sale at a pet store or online often supports the horrible puppy mill industry. Some pet stores lie about where they get their dogs from, a lot of the time they are from puppy mills. The Humane Society says in order to help stop puppy mills we need to do research before buying a dog or adopt from a local shelter or rescue.