On Puppies, Pet Stores, and Behaviour Problems

Research finds puppies from pet stores are more likely to have behaviour problems than those from non-commercial breeders.

Puppies from pet stores are more likely to have behavior problems - but this cute puppy is sleeping

By Zazie Todd, PhD

If you buy a puppy from a pet store, could you be getting more than you bargained for? It has long been thought that puppies from pet shops might have behavioural problems. A new study by Franklin D. McMillan et al investigates this by comparing puppies from pet stores to those from non-commercial breeders.

The puppies that are for sale in pet shops originate from commercial breeding establishments, also known as puppy mills or puppy farms. These are large establishments that breed puppies for profit.

The ASPCA says they “usually house dogs in overcrowded and unsanitary conditions, without adequate veterinary care, food, water and socialization. Puppy mill dogs do not get to experience treats, toys, exercise or basic grooming. To minimize waste cleanup, dogs are often kept in cages with wire flooring that injures their paws and legs—and it is not unusual for cages to be stacked up in columns.”

This page contains affiliate links.

A large number of dogs took part in this study: 413 dogs that were bought as puppies from pet stores, and 5,657 that were obtained from breeders. Although predominantly in the US, some were in other countries. Dogs from breeders were likely to have been obtained at around the same age as dogs from pet stores, and also to be purebred dogs, so they are a good comparison group to the pet store dogs.

Participants answered an online questionnaire that included the C-BARQ (Canine Behavioural Assessment and Research Questionnaire). This is a standardized questionnaire that assesses 14 behavioural factors as well as a number of miscellaneous items. 

The pet store dogs were significantly worse than breeder-obtained dogs on twelve of the fourteen scales (on the other two scales, they were about the same). The biggest differences were in terms of aggression. Looking only at entire/intact dogs, those obtained from pet stores were three times more likely to display aggression directed at their owner, and almost twice as likely to show aggression to other dogs they did not know, compared to dogs obtained from a breeder.

This is terrible, because aggression can have serious consequences for both dog and owner. 

Other problems that were found significantly more often in dogs from pet stores are aggression to strangers, aggression to other dogs in the household, fear of dogs, separation problems, and touch sensitivity.  They were also more likely to have miscellaneous problems such as soiling in the house and mounting. They were more excitable, energetic, attention-seeking and, if they were not working dogs, they were also rated as less trainable.

Puppies from pet stores are more likely to have behavior problems, especially aggression; illustrated by a cute Siberian Husky puppy
Photo: ingret; top photo, watchara (both Shutterstock)

The authors suggest several reasons for these findings. They say “the formative stages of the puppy’s life in the CBE [commercial breeding establishment] are periods where stress may exert an impact on brain development.”

The puppies are likely stressed by their environment both prenatally and during the first eight weeks of their life. They may experience stress during transit when they are shipped to the pet stores. They also miss out on important early socialization experiences because they are not able to get used to a normal household environment during this time.

It is possible that other factors play a role, since people who get puppies from pet shops may be different from those who go to breeders; for example, they might be less knowledgeable about puppies and the importance of early socialization, or tend to use different training techniques. These were not assessed in the current study. 

This is not the first research to find problems with dogs from puppy farms. An earlier study of dogs that were used as breeding stock at CBEs and then re-homed found they had significantly more health and behavioural problems than a sample of non-puppy mill dogs that were matched for age, breed and gender.  And a study by Carri Westgarth last year showed that it’s best to see both parentsbefore purchasing a puppy; if neither parent was seen, puppies were 3.8 times more likely to have a behavioural problem than if both parents were seen. 
Some places have banned the sale of puppies in stores. You can help by not purchasing anything from pet stores that sell puppies.  It’s also important to know that puppies from puppy farms are not just sold in pet stores; they are widely available via free ads and the internet, sometimes with semi-convincing cover stories about new pups that suddenly need to be re-homed.

Warning signs include wanting to meet at a neutral location (instead of where the pup was raised); the same puppy photo appearing in different adverts; and the same phone number appearing in adverts for many different puppies. For more information, see my post on how to choose the right puppy.

If you want to know more about puppy mills, you can read a closer look at puppy mills by the ASPCA, information from the BC SPCA, or join the Dogs Trust battery farmed dogs campaign. And please share the results of this research, so that people understand buying puppies from pet shops has risks of behavioural as well as health problems.

Are puppies for sale in pet stores near you?

Zazie Todd, PhD, is the author of Wag: The Science of Making Your Dog Happy. She is the founder of the popular blog Companion Animal Psychology, where she writes about everything from training methods to the human-canine relationship. She also writes a column for Psychology Today and has received the prestigious Captain Haggerty Award for Best Training Article in 2017. Todd lives in Maple Ridge, BC, with her husband and two cats.

Useful links:
McMillan, F., Serpell, J., Duffy, D., Masaoud, E., & Dohoo, I. (2013). Differences in behavioral characteristics between dogs obtained as puppies from pet stores and those obtained from noncommercial breeders Journal of the American Veterinary Medical Association, 242 (10), 1359-1363 DOI: 10.2460/javma.242.10.1359  
McMillan, F., Duffy, D., & Serpell, J. (2011). Mental health of dogs formerly used as ‘breeding stock’ in commercial breeding establishments Applied Animal Behaviour Science, 135 (1-2), 86-94 DOI: 10.1016/j.applanim.2011.09.006  
Westgarth, C., Reevell, K., & Barclay, R. (2012). Association between prospective owner viewing of the parents of a puppy and later referral for behavioural problems Veterinary Record, 170 (20), 517-517 DOI: 10.1136/vr.100138
Photo: ingret (Shutterstock.com)
P.S. Why you need to socialize your puppy

As an Amazon Associate I earn from qualifying purchases. As an Etsy affiliate, I earn from qualifying Etsy purchases.


  1. Great post. One can't emphasize enough the importance of those early weeks in a puppy's life, when both environment and human interaction shape a dog's future. Puppy socialization, with an informed program of introductions to new sights, sounds, smells, tastes, and handling are critical to a happy, social dog. Puppy mills don't provide this, and neither do many irresponsible backyard or even registered breeders. The best breeders will be able to discuss their breeding goals AND their socialization program with a potential buyer. That said, there are some wonderful young adult and adult dogs in rescues and shelters just waiting to be adopted - and some of them probably came from bad beginnings but were born with great temperaments.

  2. Thanks for your comment. I agree completely! Socialization is so important. And there are some fantastic puppies and adult dogs in rescues and shelters, which use foster homes to ensure puppies get the extra care and socialization they need.

  3. Did they test for toxoplasmosis ?

    1. Thanks for your question. The answer is no, in this case they didn't test for toxoplasmosis because they were only looking at behaviour, not health issues. If you want to know more about the typical health problems found with puppies from puppy mills, you could follow the links to the ASPCA etc. as they have a list.

  4. I think it all comes down to like previously stated the puppies need the same kinds of stimulation needed by human babies in their early years. Pupped need cognitive, social, and physical stimulation in order to develop properly. If born into bad places of course the animal will develop more agressive or other typed of unwanted behavioral issues in adulthood. Like CAPB stated those awesome rescue shelters could always be better for the dogs than being born and raised in a animal shop for the reason of receiving better socialization and stimulation. Thanks for the post!

    1. Thank you for your comment. I'm really glad there is more awareness now of the need for socialization and hopefully more and more people will become aware. Many rescues are amazing and work very hard for their dogs & puppies, and to keep up-to-date with best practice. This piece of research is an important one and at the same time it makes me very sad to think of the conditions in which these pet store puppies are raised.

  5. I think terms such as "positive/ negative punishment" and "positive/negative reward" definitely need to be clarified, since most people take their meanings to be postive=reward & negative=punishment. Without college classes in psychology, people don't know. This use of the word "positive" means ADDING something, & negative means REMOVING something. For instance, positive reward means ADDING something that will increase liklihood of a desired response, such as
    giving a dog a cookie when it sits. Positive punishment means ADDING something that will make a response less likely to occur. For example, Adding a smack on the rump when a dog wets on the couch.
    Negative reward means REMOVING a stimulus to make a behavior more likely to occur.An example would be stopping/REMOVING the electrical shocks to a rat's feet each time he presses the lever. He learns that all he has to do is press the lever to make the shocks stop, & comes to press it more & more quickly. Negative punishment means REMOVING something to make a behavior less likely to occur. Example: REMOVE an adolescent's iphone when he breaks curfew.

    Negative reward means REMOVING something to make a response more likely to occur. For instance, when a mouse finally presses a lever, one stops the electrical shocks occuring to it's feet. Negative punishment

  6. Great article; I believe it simply re-affirms what many animal lovers knew; animals and pet shops are a bad mix! I'm so glad Franklin D. McMillan et al did such a comprehensive research though and truly do thank him for releasing his findings!

  7. In my opinion, this information really reinforces something many people have thought for a long time - that dogs (and cats and cows and lots of other animals) have very similar childhood needs to humans, and that significant disruption or trauma has long lasting effects into adulthood. We wouldn't remove a child from its parent as an infant without providing it with care, love, attachment, connection, etc, and we have seen that children who experience poor attachment and care in infancy can grow up to have significant social, physical and mental issues. I think it follows that this is the same for animals, and I wish more people knew this (about humans and animals, actually!)

  8. I have worked with service dogs in several countries and WOW they are treated WELL, and so don't get a "dogs PTSD"... I also lived in countries where selling pups in shops did not happen... so there were no puppy-mills... one had to go to a breeder ans SEE the mum of the pups and the conditions there. One would think the dogs in such a country were more healthy? I think they are... they are also more expensive. Initially. But hey.... some of the bargain pups from mills end up costing the owner A LOT in a short time due to infections, need for expert training and so on? For US I suggest a study in total COST as well, since money speak so loud here...

  9. What about stray mom's puppies? My sweetheart was rescued when she was 15 weeks old, all by herself on the streets. She's 9 and our walks are nothing but endless food searches...


Post a Comment

Popular posts from this blog

Don't Punish Your Dog for Peeing in the House

What Is Positive Punishment in Dog Training?

Eight Tips to Help Fearful Dogs Feel Safe