I have always believed that there are a million reasons not to buy dogs from pet stores. Most of those can be boiled down to two words: puppy mills. But now I have found the million and first reason: According to a new study, pet store puppies have higher rates of behavioral problems as adults, relative to puppies obtained from breeders.

Please do not take this article as an endorsement of buying from breeders. I’m a shelter/rescue man. My pal Buster is from the pound. I will never buy a dog from a breeder, or from anywhere. I don’t believe in buying things that can be had for free, and I believe, in principle, that it is good and honorable to rescue dogs.

I have had extensive experience with bad and unethical breeders. Consider the owner of the pregnant Shih Tzu who was presented to my office not long ago for a cesarean section. The dog had a heart murmur, retained deciduous teeth, entropion, and an umbilical hernia. All of these problems are potentially hereditary.

The mother also was suffering from dystocia, or the inability to deliver puppies. No ethical person would continue to breed such a dog, but her owner insisted that she not be spayed. He didn’t care that this would endanger the mother and potentially create more puppies with problems later on. He cared about nothing but money.

Of course, not all breeders are unethical, but it can be hard for someone buying a puppy to distinguish between a good one from a bad one. The bad ones often talk a good talk. But this article isn’t about breeders; it’s about pet stores.

Breeders are only involved because the study compared only two groups of puppies: those purchased from pet stores and those purchased from breeders. It sought to determine whether puppies purchased from pet stores might go on to develop more behavior problems as adults. The answer was a clear yes.

Owners of these puppies were questioned about the behavior of their dogs as adults. The survey compared undesirable behaviors such as separation anxiety, owner-directed aggression, stranger-directed aggression, dog-directed fear or aggression, mounting of objects or people, and house soiling.

The results speak for themselves. The authors state, “Pet store-derived dogs received significantly less favorable scores than did breeder-obtained dogs on 12 of 14 of the behavioral variables measured; pet store dogs did not score more favorably than breeder dogs in any behavioral category. Obtaining dogs from pet stores versus noncommercial breeders represented a significant risk factor for the development of a wide range of undesirable behavioral characteristics … the authors cannot recommend that puppies be obtained from pet stores.”

The why of the matter is purely speculative, but again it appears to boil down to my favorite bugbear: puppy mills. Pet store dogs generally come from puppy mills, and such dogs suffer stress in utero and in early puppyhood during crucial periods of brain development. They do not experience proper socialization with humans or other dogs. They suffer transport stress at a young age.

I will concede that the studies might also compare apples and oranges, because the sort of person who purchases a dog from a pet store is … the sort of person who purchases a dog from a pet store. Such dog owners might not put as much effort into their dogs as other people.

Now, before breeders use the study and this article as an argument in favor of dog breeding, let me point out that this study was run to make up for the minor deficits of another study. A previous study showed that pet store dogs suffered more behavioral problems than breeder dogs, animal shelter dogs, dogs obtained from friends or relatives, dogs found and rescued from the streets, and dogs that were home-bred. However, this study used only a small sample of pet store dogs, so the new study sought to replicate the results on a larger scale. And it did.

Therefore, this new study should not be taken as an endorsement of breeder dogs, but rather as another reason not to buy dogs from pet stores. I intend to stick with animal shelter dogs or dogs found and rescued from the streets.

The study discussed in this article is McMillan et al, J Am Vet Med Assoc 2013;242:1359-1363. It was published so recently (May 15, 2013) that I am not able to find a link to it at press time, but here is a link to a PDF of the abstract.

Other stories by Dr. Eric Barchas:

• The Top 8 Summer Hazards for Dogs
• What’s Euthanasia Like for a Vet? The More I Do, The Harder It Gets
• Is Your Flea-Control Product Hurting Your Dog?

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