Visiting Vet: Canine compulsive disorder

When does repetitive behavior cross the line into pathology? 

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I’ve known Stanley, an energetic Labrador-cocker mix, all his life. One November when he was 8 years old, he started nibbling fur on his feet, from his toes to his “ankles.” The end result was that, despite a beautiful coat everywhere else, the lower portion of all four legs had a scruffy, flea-bitten appearance, the fur thin and irregular, with tiny bald patches. When animals pull out their fur, veterinarians immediately think fleas, or allergies. Inhalant allergies to pollen, mold, or mites. Food allergies. Even contact irritants, or allergies to fibers or cleaning products. 

I checked Stanley carefully for evidence of fleas. None. Was he getting good flea control? Yes, a Seresto collar. Had there been a change in diet or anything new in his environment? No. “It’s probably seasonal allergies,” I said casually, and prescribed a course of the corticosteroid prednisone, which would reduce itchiness, regardless of the cause. 

The following September Stanley started biting his legs again. This time we found fleas, and switched to an oral flea product that is virtually 100 percent effective. By November Stanley was again flea-free, but still licking his legs. Hoping the issue would pass with continued flea control and the changing season, as it had previously, we opted for “tincture of time.” In other words, wait and see if it got better on its own. 

It didn’t. By his next visit Stanley was pulling out the fur on his legs year-round. We tried various medications to reduce itching. Although some seemed to help a little, nothing worked really well, and nothing worked consistently. The initial seasonality suggested pollen allergies, but the fact that it was now year-round and not responsive to traditional therapy added another possibility to our differential list. Could Stanley have a behavioral issue rather than, or in addition to, an allergy-driven one?

Canine compulsive disorder (CD) is defined as abnormal repetitive behavior related to anxiety or stress, without any other apparent initiating cause. Diagnosis is made essentially by ruling out all other behavioral or physical triggers. There is often a genetic component, with specific breed predispositions to each type. CD has been compared to obsessive-compulsive disorder in humans, with studies showing these dogs may have altered function in certain regions of the brain, and differences in serotonin-receptor binding, an important aspect of normal neurotransmitter activity. There are several categories of CD based on the main characteristics of the behavior. 

Locomotor CD manifests with motions such as circling, spinning, tail-chasing, and excessive pacing. Breeds predisposed include German shepherds, bull terriers, and Australian cattle dogs. Now, breeds like cattle dogs are raised to run huge distances herding livestock over vast terrain, not to sit in someone’s house all day. Pacing or spinning may be a “vacuum activity,” occuring in the absence of having a job like herding to occupy the dog’s mind and provide sufficient exercise. Some dogs just need adequate environmental stimulation and exercise. Others, however, may exhibit markedly abnormal activity no matter how busy they are. 

Visual or hallucinatory CD is manifest by light or shadow chasing, or “fly snapping,” an odd behavior in which the dog repeatedly bites at the air as though trying to catch flies. Breeds predisposed include Cavalier King Charles spaniels, border collies, and terriers. These behaviors may be associated with eye diseases, or a neurological condition called syringomyelia. 

Self-directed or self-injurious CD occurs in animals who suck, lick, or chew on themselves to the point of real self-harm. It includes flank-sucking in Doberman pinschers, hind-end checking in Schnauzers, and acral lick dermatitis in large breed dogs. Is this Stanley’s situation? Oral behaviors like excessive licking can be confusing, as they may not be “compulsive” at all, but rather triggered by discomfort from conditions such as gastrointestinal disease, orthopedic pain, even bladder stones. Is that big dog licking his legs because of a behavioral problem or because he has arthritis and hurts, or allergies and itches? When does repetitive behavior cross the line into pathology? 

True CD, i.e., abnormal behavior that is primarily psychological without other triggering causes, usually starts young in dogs, often by a year of age. But normal energetic young pups may chase their tails, or spin in circles, and dogs of any age may lick their paws for various reasons. How do we tell coping mechanisms from bad habits from serious disease? In many cases, the behavior is so dramatic, so clearly abnormal, diagnosis is easy. But others are less obvious. If only Stanley could talk. He might tell us, “I’m so itchy,” or “My joints ache when the weather changes,” on “I’m feeling anxious,” or even “I don’t know why I do it but I can’t seem to stop.” The best we can do is a thorough examination and laboratory tests to look for physical causes, then a comprehensive history and behavior evaluation, even consultation with behavior specialists, to suss out psychological components to the problem.

Once a presumptive diagnosis of CD is made, treatment usually involves both medication and behavioral modification, often lifelong. Goals are to minimize the behavior, find a substitute to replace it with, and reduce stress. Punishment is contraindicated, as it will only create more anxiety. No medications are specifically approved for treatment, but many human antidepressants have been used with moderate success, when combined with environmental and behavioral changes. 

I don’t think Stanley has true CD. His licking started fairly late in life, and the prednisone seems to be helping more this time around. His primary issue is probably allergies, but I suspect his high-strung nature, and the learned behavior of habitual licking, have contributed significantly to this problem. Options now include continued anti-itch medication, allergy testing and desensitization, hypoallergenic elimination diet trial, and behavioral modification. But it is also worth considering psychotropic medication. Stanley does not lick himself raw, and we love him even with scruffy-looking legs, but if this behavior is in part an external manifestation of internal anxiety, we want to pay attention and provide relief.