A study published in the Journal of the American Veterinary Medical Association (JAVMA) has concluded that dogs obtained from pet stores as puppies are more likely to develop undesirable behavioral characteristics than puppies obtained from non-commercial breeders.

The study's authors conducted a cross-sectional study to gather data from 5,657 pet owners who obtained their puppies from breeders, and 413 owners who obtained puppies from pet stores. They collected data using the Canine Behavioral Assessment and Research Questionnaire (C-BARQ), which is a standardized survey instrument that provides quantitative assessments of dogs' behavioral characteristics.

According to the results of the data analysis, dogs obtained from pet stores as puppies scored worse than breeder-obtained dogs in almost all behavioral variables measured, the study authors reported.

"Results of the present study indicated that compared with dogs obtained as puppies from NCBs (non-commercial breeders), dogs obtained as puppies from pet stores had significantly greater aggression toward human family members, unfamiliar people, and other dogs; separation-related problems; and urination and defecation problems in the home," the authors wrote.

While researchers said the data supports the idea that pet store dogs tend to exhibit worse behavior, they wrote that they could not point to a just one definitive cause for the behavioral problems. For stranger-directed aggression alone, they listed several possible causes including inadequate socialization, maltreatment by humans, genetic factors, and prenatal stress.

The authors also discussed previous research studies showing that stress in a dog's early life can set the stage for behavioral problems later in life. According to the authors, puppies from pet stores may be more exposed to stressors in their early lives including transport-related stress, spatial restriction, limited access to positive human and conspecific social interactions.

"Substantial evidence in humans and other animals indicates that stressful experiences in early life may have extensive and enduring effects with strong correlations to later development of behavioral abnormalities and psychopathologic abnormalities," the wrote.

The researchers wrote that more studies are needed to determine specific causes of the behavioral differences between the two groups of dogs, and until the additional research is conducted they cannot recommend obtaining puppies from pet stores.

"On the basis of these findings combined with earlier findings regarding pet store-obtained dogs, until the causes of the unfavorable differences detected in this group of dogs can be specifically identified and remedied, we cannot recommend that puppies be obtained from pet stores," the study's authors wrote.

Read the full study in JAVMA (paid only)