Puppy Mills’ Damage to Mental Health

Many subtle things go into canine behavior. Have you ever had a dog with significant behavior problems even though you did everything right? Not just a minor lapse like a snatched sandwich, but issues such as anxiety, fear, impulse control, aggression, obsessive-compulsive disorders? Just like people, dogs are bundles of influences, a mixture sometimes called GEE: genes, environment, and experience. “Good genes” might give a dog a leg up on trainability and dealing with its environment; and dogs, like people, can also inherit trouble.
A recent study touches on the crucial second and third parts. It shows a remarkable correlation between the age when a puppy leaves its mother and whether it has behavior disorders.
Researchers led by Italian veterinarian Ludovica Pierantoni checked in on two groups of adult dogs: some who had been separated from their dam and litter for sale or adoption at 30-40 days old, and some who had been acquired at 60 days. They found that the dogs separated young were significantly more prone to unwanted behaviors: excessive barking, fear on walks and around strangers, stranger aggression, and destructiveness.
That socialization period for dogs is critical. It’s when these highly social animals get their start on life. In a mere 2.5 to 14 weeks—some researchers think the window may be even shorter—a puppy tunes into signals from its mother and littermates to establish a secure base for exploring its world and gaining confidence.
Puppies raised to be sold are hurried into the marketplace and robbed of these vital interactions. The Italian study reported that a significantly higher proportion of dogs bought from pet stores showed destructiveness, excessive barking, toy possessiveness, reactivity, fearfulness, and aversion to strangers. They theorized that these dogs had come from puppy mills—and we know puppy mills supply virtually all pet shop puppies—and called for intervention:

Behavioral intervention can address the development of problem behaviors and improve the dog’s relationship with the owners, ultimately reducing the number of dogs that are relinquished or abandoned.

Intervention sounds hopeful, but the damage may already be done. Many studies have pointed out the permanence of puppy trauma and poor socialization. Because a bad start is such a big obstacle in the broad struggle to keep dogs healthy and in happy homes, it’s clear why it’s so important to stop supporting the pet shops or online vendors/brokers who work with puppy mills.
Breeders who rush pups out the door also have mother dogs living in chronically stressful environments. They develop lifelong problems too, as I’ll get to in a moment.
What happens in early life matters on a deep level—cell deep, in fact. Severe stress or trauma causes stress hormones (glucocorticoids) to be released and affects the structural development of the hippocampus—the part of the brain that handles associative learning and integrates that learning into cortical function. Among lab rats, prenatal and ongoing chronic stress causes shrinking of the hippocampus and difficulties in controlling fear. Scale that up to dogs and you realize that investing in adequate socialization—60 days—with littermates and dams is a small price to pay if it saves pups from a lifetime of fear or abandonment.
A related sort of trauma, that of dogs used for breeding, shows through in Franklin McMillan’s recent research on puppy mill breeding stock. You can find it in Applied Animal Behaviour Science. McMillan gauged their mental health by comparing the psychological and behavioral characteristics of 1,169 rescued former puppy-mill dogs (70 percent female, 30 percent male) with those of 332 pet dogs that had no mill history.
The most striking difference was in their level of fear. Dogs coming out of puppy mills exhibited far more fear in response to people, other dogs, and stairs. Some seemed to have learning disabilities: less trainable and less energetic. They were worse at house-soiling and compulsive behavior. Heartbreaking too, the mill dogs were more fearful of being touched, and more prone to “star(ing) intently at nothing visible” and “shadow chasing.”
For many of these victims, the fears continued even after years in their adoptive households. The authors say the most likely reasons are “stress-induced psychopathology and inadequate early socialization and/or lack of exposure to environmental stimuli normally found in the lives of typical pet dogs.” In other words, the lack of any normal canine life. For either the mother dogs or their puppies. I’m sure that the more you learn about the real face of puppy mills, the more you’ll shun them.