In brief, Puppy Mills hurt dogs in several ways. Puppy Mills promote negative genetic traits, keep breeder dogs in inhumane conditions and sell puppies that often are ill or die soon after being purchased.
Read about The National Mill Dog Rescue
This post was inspired by this article. http://www.examiner.com/dog-behavior-in-san-francisco/puppy-mill-awareness-day-hopes-to-educate-the-public?CID=examiner_alerts_article