When we’re extremely frustrated, we say we are “pulling our hair out.” People often pull their hair or engage in self-grooming when they’re under stress. Stuck at a traffic light, for example, stymied motorists start adjusting their hair in the rearview mirror. They can get so wrapped up in what they’re doing that when the light turns green, a honk from behind is needed to get them to move on. An extreme form of hair pulling—the obsessive-compulsive disorder known as trichotillomania—can leave people practically bald.
Like people, like cats. Felines engage in a version of hair pulling and excessive grooming called psychogenic alopecia. The cat compulsively licks itself, almost invariably on the parts of its body that it can reach most easily. That would be the “undercarriage”—the chest and abdomen and inside the front or back legs. Bald patches often result. Cats that exhibit such behavior are high-strung types, often of Oriental breeds like Siamese, suggesting that the roots of the disorder are genetic.
In the cats we see, psychogenic alopecia is often brought on by a stressful experience, such as an owner’s prolonged absence or the arrival of an unwelcome visitor. If the stressful situation ends immediately, that might put a stop to the excessive grooming. But if the stress persists, the behavior can take on a life of its own, becoming ingrained in what could be thought of as well-worn neural pathways.
One of the first cases of psychogenic alopecia I saw illustrates how directly the condition is linked with stress. The cat was owned by a good friend and colleague, the late Robert Fleischman, then a veterinarian in Northborough, Mass. Bob had adopted this cat after it was brought into his clinic as a stray. The trouble was, he already had another cat at home—a tortoiseshell that did not appreciate having company.
From the get-go, the incumbent was hiding, hissing and running away from its new housemate. Within hours it began to groom itself compulsively along the underside of its body. Bob contacted me for help. I treated the cat with a drug that blocks the effects of opioids—believing in those days that nature’s own morphine-like substances, the endorphins, were involved in propagating repetitive behaviors. (I now realize that I was actually blocking glutamate, a neurotransmitter that aids in the formation of memories.) The cat’s condition improved considerably, but the medicine was extremely bitter, and it became almost impossible to administer it to the cat. Bob and his wife decided it was easier just to let the cat keep licking.
As part of our ongoing efforts to study compulsive disorders in animals, my colleagues and I propose to delve deeply into the genetics of feline psychogenic alopecia. Ultimately, we hope to find a common gene that confers susceptibility to the whole range of compulsive disorders. Along with that, we hope to find modifier genes that determine how severe a sufferer’s compulsive disorder might become, and what kinds of behaviors could result.
It’s apparent that an animal may have the gene for compulsive disorders without displaying any compulsive behaviors. But in research on Doberman dogs, we have discovered genetic clues as to how likely these unaffected animals are to develop a compulsive disorder if they’re exposed to stress.
The gene that makes cats susceptible to feline alopecia might prove to be the same one that makes people susceptible to trichotillomania. Perhaps it will even turn out to be the one behind other compulsive disorders in both humans and dogs. Such findings could lead to a better understanding of, and treatment for, compulsive behavior—yet another instance of veterinary research benefiting animals and people alike.
This article first appeared in the Summer 2012 issue of Tufts Magazine.
Nicholas Dodman directs the Animal Behavior Program at the Cummings School of Veterinary Medicine. He has written several bestsellers, including The Well-Adjusted Dog.