As consumers finalize their Christmas shopping plans, the Humane Society of the United States encourages families to avoid buying puppies from pet stores and online sellers. Pet stores typically source from puppy mills–which often are associated with hidden illnesses, overwhelming veterinary bills and a cycle of suffering for mother dogs–as do online puppy sellers, and that’s if the puppy in the photo even exists! Too often, either of these choices lead to heartbroken families. Here’s how to avoid falling victim to a puppy scam or supporting a puppy mill if you’re looking to bring a new pet into your home this holiday season. Scam alert! Why you should never buy a puppy online:…