A study, co-authored by James Duffy, Deborah Duffy and Frank McMillan published in The Journal Of The American Veterinary Medicine Association in May, 2013, proves that puppies purchased from pet stores show an increased prevalence for behavioral problems as adults. The study, motivated by findings in a 2011 study by the same authors showing showed greater psychological problems in adult dogs rescued from commercial breeding facilities (also known as puppy mills) might suggest that turbulent early lives of dogs in commercial breeding facilities might be the reason for future undesirable behaviors. The extent of the abnormalities in dogs sourced from large-scale breeders was dramatic. Pet store puppies showed an increased risk of aggression toward their owners and other dogs, as well as a greater chance of escaping, roaming, and running away. Neutered dogs fared somewhat better, but still showed a higher risk of aggression than neutered dogs from non-commercial breeders. Serpell says puppies that end up in pet stores often live a disrupted early life and tend to be poorly socialized; he says they are weaned and separated from their litters too early, however, until the causes of the differences detected in puppies from pet stores can be speciﬁcally identiﬁed and remedied, Serpell and McMillan say they cannot recommend that puppies be obtained from pet stores.