The only way to shut these inhumane puppy mills down is to close down the pet stores that keep them in business--or one other alternative: convince the pet store owners to remain open and go humane by offering adoptable dogs from shelters. It can be done. The Los Angeles area has seen quite a few pet stores adopt a humane model. Here is how to convince a store owner it is the right and humane decision.
Instructions
Ask to speak to the owner of the pet store. Ask if he/she knows about puppy mills. Odds are, they will say yes, but will tell you that they don't get their dogs from puppy mills. This is likely not true, and they are telling their customers this as well, which is basically consumer fraud. Write down what the owner tells you. The most common tale is that their pets come from individual breeders that raise the dogs in their homes.
Request the breeder information on a few particular dogs they have for sale, which they are required by law to provide you with. There is a good chance the breeder is located in the Midwest, "the puppy mill capital of the United States," or perhaps Lancaster, Pennsylvania, "the puppy mill capital of the East Coast" where many Amish "farmers" have puppy mills. The store owner should be willing to provide you with that information. Why not? They figure you're not gonna make a trip there anyway, especially if the mill is in Missouri and you're in California, New York or Florida.
Feel out the pet store owner and see if he/she seems friendly and open enough to listen. Then ask if they are familiar with all of the pet stores in the Los Angeles area that went from selling puppy mill dogs to having adoptable dogs from shelters. Keep in mind that they are in business to make money, and the only way this will work is if they offer other services such as grooming and/or have a large enough inventory of pet supplies. If they only sell dogs, they may not be a good candidate for having only adoptable dogs from shelters (they won't be able to charge nearly as much). Suggest to them to look into these humane stores and see how they stay successful. (See Resources below for links to articles about humane pet stores. Perhaps you can print out copies and give them to the owner.) Inform the owner (without it sounding like a threat) that various pet stores in the Los Angeles area, which opted not to switch to a humane model, were forced to shut down due to continued protesting.
Refer the owner to Best Friends Animal Society or Last Chance for Animals (see Resources), two reputable organizations that have helped pet stores transition from selling puppy mill dogs to rescuing shelter dogs instead. They also help promote these humane stores.