A new study has found that puppies purchased from pet stores are more likely to have behavioral problems later in life than puppies purchased from breeders. According to researchers at the University Of Pennsylvania School Of Veterinary Medicine, who conducted the study, puppies from pet stores carry a much higher risk of developing behavioral problems due to increased aggression, fearfulness, sensitivity, and separation-related issues.

Researchers say this is primarily due to the fact that pet store puppies are not adequately socialized during their first few months. Another factor, says study leader Dr. Frank McMillan, is prenatal stress. Commercial kennels, says McMillan, typically keep puppies and their mothers in small enclosures with little human interaction. For pet owners that end up with pet shop pups, McMillan recommends starting training as early as possible.