Study of effects of puppy mills on dogs' emotional health

Dr. Frank McMillan of Best Friends Animal Society begins a long-term scientific study on the effects of puppy mills on the emotional health of dogs.
By Amy Abern

By the end of his first week with the dogs rescued from a decrepit Virginia puppy mill, Dr. Frank McMillan had evaluated the baseline emotional well-being of more than 120 of the adult dogs used in the breeding operation. Dr. Frank’s analysis is part of a Best Friends' study on dogs who are subjected to the isolation and deprivation of mass commercial breeding conditions.

First scientific study on toll puppy mills take on dogs

"There’s no scientific data out there," says Dr. Frank. "Any information at all is anecdotal. We’ve all heard about the physical conditions of dogs in puppy mills, but there’s no hard science about the psychological effects of those conditions."

It’s estimated that there are more than 10,000 puppy mills in the United States. Most of them operate as clandestine operations to avoid government regulation. They range from huge operations hidden in remote barns to backyard breeders keeping dogs in sheds and trailers. Although every state has puppy mills, Virginia is becoming one of the largest puppy mill centers in the nation. Altogether, such mills produce an estimated four million puppies per year.

A cruel irony: an estimated four million homeless animals are killed every year to control pet overpopulation in the U.S.

Inhumane conditions in puppy mills

It’s clear from the lengths puppy mills will go to in order to hide their operations that they know their dogs are being subjected to inhumane conditions.

Many puppy mills have their dogs stacked in small cages in the dark so they won’t bark and attract attention. With almost no medical care, breeding females are forced to produce two litters a year until they wear out and are discarded. Not only do these forced-bred dogs suffer from numerous illnesses, so do their puppies who are sold to pet stores, over the Internet, or directly to unwitting consumers. In addition to generic disorders and other ailments that appear months or years after these puppies are purchased, they frequently come out of puppy mills with parasites and infections, heart ailments, and other diseases.

In addition, the inhumane conditions in puppy mills, isolation, lack of human or animal contact and socialization, and confinement in small cages can have a profound psychological impact on the animals – particularly the breeding females. And while there is considerable evidence of the impact of puppy mills on dogs’ physical health, little research has been done on the short- and long-term mental health problems in dogs bred or held captive in these deplorable conditions. It is this aspect of puppy mill cruelty that is the focus of Dr. Frank’s research.

It’s an ambitious project, especially for a man who is taking on the Whole Health Initiative at Best Friends, collaborating with our medical team, introducing several new therapeutic disciplines, and conducting research into animal behavior and emotional well-being.

Dr. Frank had just moved from his California home to Utah when Best Friends became involved in rescuing 179 dogs from the Virginia puppy mill. "This rescue happened so fast," says Dr. Frank. "But I’m glad to be working on this, because there’s just nothing out there describing the long-term emotional and psychological effects in puppy mill dogs."

Dr. Frank McMillan's veterinary career

Long before arriving at Best Friends, Dr. Frank had built his veterinary career on the premise that animals’ emotional well-being is as important as their physical comfort, an epiphany born from a personal disaster. Dr. Frank lost his home in the 1994 California earthquake. As he slowly picked up the pieces of his life, he realized how important his emotions were in guiding every decision he made. And when those emotional needs were met, he felt stronger physically.

Dr. Frank began looking at the way he practiced veterinary care in a new light. He’d see stress in a dog’s eyes and wonder about its origin. He took note of animals’ delight at the sight of their human companions. A few affectionate strokes served as the perfect elixir for an animal in pain. Medical treatment often didn’t factor into these equations. Compassion, or lack of it, did.

Over time, the idea that true veterinary care includes an animal’s emotional well-being as well as physical health became the golden rule dictating Dr. Frank’s veterinary practice as medical director at the VCA Miller Animal Hospital in West Hollywood, California. In his book, "Unlocking the Animal Mind," Dr. Frank builds a strong case for his basic philosophy: Feelings rule.

The puppy mill study protocols

Dr. Frank arrives at Pets Alive prepared. He uses an evaluation form adapted from research by colleague James Serpell from the University of Pennsylvania; the template has been published in the Journal of the American Veterinary Medical Association.

For this study, Dr. Frank can have no prior contact with the dogs--not even casual visual connection. He sets himself up in an empty room with as little distraction as possible. He sits on the floor so that when he meets the dogs for the first time, he’s on their level. A volunteer opens the door, sets the dog in the room and leaves. Dr. Frank runs through a 20-minute battery of tests, looking for some kind of reaction to various stimuli:

  • Dr. Frank gently asks (rather than commands) the dog to come.
  • He walks back and forth, watching for the dog’s reaction.
  • Dr. Frank strokes the dog, if the dog will allow it.
  • He rolls a small ball by the dog.
  • Dr. Frank opens an umbrella, creating a loud, sudden noise.
  • He hugs the dog, if the dog will allow it.
  • He creates another loud, unexpected sound by dropping an aluminum can.

Throughout, he checks for behavioral reactions and physiological responses like pupil dilation and changes in heart rate.

So far, he’s seen nothing dramatic or surprising, which is just as he expected. This initial testing is necessary to set the stage for further study.

"I knew I wouldn’t be making statements like ‘The five adult female pugs all exhibited extreme fear when I opened the umbrella,’" he explains. "I’m conducting very general research at this point. I’m looking at basic sociability and fear factors. Eventually, this information can be connected to later research to see which long-term effects can be predicted by these initial findings."

Dr. Frank has a couple of general observations: Responses from the dogs vary from severely frightened and agitated to friendly. Part of his research will explore why some dogs subjected to isolation and lack of socialization in a puppy mill environment are more resilient and don’t exhibit the same signs of emotional trauma as others.

"In pure research, you can’t have an agenda," explains Dr. Frank. "You have to let the data speak for itself and then draw conclusions. The only conclusions I’ve drawn from this is that some of the dogs exhibit what I would consider typical behavior due to abuse and neglect, while others are very well-adjusted. But again, it’s a wide spectrum. Whatever we learn, we learn."

Honesty is of utmost importance

Dr. Frank also points out that absolute honesty in reporting is essential to the credibility of not just the study, but also for Best Friends, the sponsor of the study. "As an animal welfare organization, of course, we have strong opinions and ideas on how animals should be treated. But we can’t shape the data to suit our purposes. And by presenting the raw data without prejudice or slant, we show we’re a credible source for future studies."

What will be interesting in the research on puppy mill dogs’ long-term emotional well-being, he says, is finding how the well-being of these current puppy-mill dogs compares to future saved puppy-mill populations. Objective evaluations of conditions at each puppy mill site will be one of the factors included in future studies.

To support this important research, donate here.

The future of the project

Of course, one of the high priorities involving the Virginia dogs is finding them forever homes. Dr. Frank will ask each of the adopters to participate in the study. The involvement requires little more than filling out a yearly evaluation form by mail, e-mail or telephone. In this way, Dr. Frank will learn how future factors continue to influence, and hopefully improve, the emotional well-being of his subjects. For instance, do children in the house help these dogs recover from the emotional trauma of their former living situation? Does having other dogs in the house help these dogs to enjoy their lives? What about cats and other animals? Does the time people spend with the dogs at home make a difference?

For now, Dr. Frank is pleased that most of the dogs seem to be doing well. "They just want to be loved and want to love back," he says. "I hope they all get that chance."

There are still a variety of health issues that must be addressed for the dogs rescued from the Virginia puppy mill. Once the dogs were rescued, Best Friends’ staff partnered with several local veterinarians to assess the health of the dogs and provide triage. One dog was limping very badly and it was discovered that the poor dog actually had feces caked between the pads on his paws!

Some of the dogs had horrible abscesses in their mouths and one had a broken jaw that had never been treated. "A good percentage of the dogs would snap at people out of fear and lack of socialization and handling," says Best Friends animal care director Patty Hegwood. "None of the dogs are used to walking outside and were quite fearful. It was obvious that most of the dogs had never touched or seen grass before. They were forced to urinate where they ate and slept, and most of the dogs had toenails so overgrown they could barely walk. Several dogs had a life-threatening uterine infection called pyometra which was so far advanced that they could have died without immediate medical attention."

It’s important to remember that animals rescued from puppy mills are not all puppies. In the Virginia rescue, there were more than 120 adult dogs. "We rescued dogs, including pregnant geriatric moms, who were being bred to death," says Patty. "All of the dogs we rescued in Virginia are dogs who have never napped on a sofa, gone for walks, been given treats or any individual love and attention. While we’re working on their health issues, we’re also giving them love and attention for the first time in their lives."

During the course of his study, Dr. Frank will offer updates on his research findings. He also welcomes readers’ comments and questions by e-mail at

Learn more about puppy mills

Learn more about puppy mills, and how commercial breeders contribute to the national crisis of homeless pets and pet overpopulation.

Photo by Molly Wald

Ending Puppy Mills