Are Dogs Purchased From Pet Stores More Aggressive?

Pups bought from pet shops develop more behavior problems, including aggression.

Posted Mar 17, 2016

Smerikal photo — Creative Commons license
Source: Smerikal photo — Creative Commons license

It is a well-established fact that the vast majority of puppies sold in pet stores come from so-called "puppy farms" or "puppy mills". In such mass breeding facilities the standards of care are often quite low and no attempts are made to socialize the young dogs. A number of different nations, states, and municipalities have been considering legislation to control the sale of puppies in pet stores. For example in England a ban was imposed on selling puppies less than eight weeks old in pet stores because of data demonstrating that pups which are separated too early from their litter often have psychological problems (click here to see more about that).

In the past few years several reports have come out suggesting that the stressful early rearing conditions and lack of socialization in the puppies usually sold by pet stores can lead to a variety of behavior problems (click here for more about that). Now a new study by a team of Italian researchers from the Department of Veterinary Science in Public Health at the University of Milan has added some new important data to our understanding of the problems associated with dogs acquired from pet stores.

In a report published in the Journal of Veterinary Behavior* a group of researchers headed by Federica Pirrone decided to compare the behaviors of dogs obtained from pet stores with those of dogs obtained directly from breeders. However these researchers decided to measure a number of owner related variables as well. This team of investigators wondered whether some of the problems observed in pet store purchased dogs were really due to the nature of the people who typically get their companion dogs from pet shops.

The reasoning is that most people who are knowledgeable about dogs have become aware of reports suggesting that the best source for getting a puppy is directly from a recognized dog breeder, and that purchasing a dog from a pet store may be a risky matter. So it occurred to these researchers that, perhaps some of the problems observed afterward in dogs obtained from pet stores, comes from the fact that many of the people who purchase puppies from pet shops are not particularly well-informed about dogs. Without adequate knowledge about dogs these individuals may be using the wrong rearing and care practices. That could mean that the problems often found in pet shop dogs might not be just be due to the source from which the store obtains its puppies, but could also be the results of the dogs' later treatment once they get to their new homes.

This problem is considerably less in dogs obtained from breeders who often go out of their way to provide information about the care and behavior of the dogs that they sell. For example, I recently obtained a new puppy, and despite the fact that the breeder knew that I have had many dogs in my life and am considered to be educated and up-to-date in matters concerning dog behavior, she still gave me a package of information about puppy rearing, and advice as to how to care for and educate my new dog.

This latest study used a web based set of questionnaires. Data was obtained on the behaviors of 349 dogs obtained from breeders and 173 dogs purchased from pet stores. In addition a lot of additional information was obtained about the owners and the way in which they treated their dogs. In the initial analysis of the data, the researchers found four behavior problems which were significantly worse in dogs obtained from pet stores as opposed to those obtained from dog breeders.

The pet shop dogs showed considerably more separation anxiety (30%) as compared to dogs from breeders (17%). House soiling was three times more common in pet shop dogs (15% versus 5%). Generalized anxiety behavior, which often appears as body licking was also considerably greater in pet shop dogs (30% versus 14% for breeders). One of the most troubling findings had to do with aggression directed at the owner or other family members, which was more than twice as frequent in pet shop dogs (21% versus 10%).

Now remember, what these investigators wanted to do was to see which problem behaviors observed in the pet store dogs were due to the nature of the people who typically obtain their pups from pet shops versus of those problems which arise as a result of the early stressors associated with being reared in a puppy mill. For this reason they ran a series of complex statistical analyses which are called logistic regressions, to tease apart the variables.

When all of this was done they found that three of the problem behaviors (separation anxiety, house soiling, and body licking) were not specifically associated with the source from which the puppies were obtained. Rather they found that the dogs with these difficulties seem to be the result of being reared by owners who simply did not know much about canine behavior. Thus, not surprisingly, people who had never owned dogs in the past were more likely to have dogs with problem behaviors regardless of the source from which the dog was purchased. Other owner-related variables that led to difficulties included not taking a dog to a basic dog obedience class, treating misbehaviors in a punitive fashion, and not giving the dog adequate exercise.

However, even when all of the owner variables were taken into account, there was one important problem which seemed to a more frequent characteristic of dogs obtained from pet shops. This was the likelihood that the dog would act aggressively toward its owner or other familiar people. Specifically the pet shop dogs were more than twice as likely to bite or threaten their owners than were dogs obtained from a recognized breeder. This increased aggression is most likely due to inadequate socialization of the puppies that the shops obtain from puppy mills, or a result of early stressors while still in the breeding facility, or possibly due to the fact that many pups showing up in such stores have been removed from their litter when they were too young.

Clearly these data sound yet another note of caution about purchasing those puppy mill dogs usually sold in pet stores. The evidence suggests that the dogs' early negative experiences may lead to later patterns of aggression against family members in their new home. On the other hand, these data also emphasize, that when owners have adequate knowledge and education as to how to treat and rear dogs they can reduce the likelihood of the most commonly observed canine behavior problems. The authors conclude that:

"The role of the breeder is not only to raise healthy and sociable puppies but also to appropriately select and educate potential owners about the importance of correct ongoing socialization and training for companion dogs."

Stanley Coren is the author of many books including: The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission

* Data from: Federica Pirrone, Ludovica Pierantoni, Giovanni Quintavalle Pastorino, Mariangela Albertini (2016). Owner-reported aggressive behavior towards familiar people may be a more prominent occurrence in pet shop-traded dogs. Journal of Veterinary Behavior 11, 13-17.