Compulsive Behavior in Dogs

A pointer mix continually licks the carpus of its right front leg, causing localized hair loss and skin lesions.

The dog is apparently healthy (medical and dermatologic problems were ruled out) and does not show any local abnormalities upon orthopedic examination, which includes radiographs. What can be done to treat the problem?

Repetitive behaviors in animals (locomotor, oral, aggressive, and vocal) that occur out of context and serve no obvious purpose are commonly described as compulsive disorders because of their similarity to the psychiatric condition OCD in humans. Acral lick dermatitis was the first canine compulsive disorder proposed as a model for OCD when psychiatrists noticed the similarities of this self-grooming behavior in dogs with that of human patients who could not stop washing their hands.¹

OCD in humans manifests in ways that may vary over the course of a lifetime. Children seem to be affected more frequently by compulsive counting. In puberty or adulthood, compulsive behaviors may change and focus on religious rites, sexuality, or cleanliness. Some people have trouble leaving home without first spending hours turning off the coffee machine, relocking the door, and repeating other such safeguarding behaviors. The Diagnostic and Statistical Manual of Mental Disorders, which classifies OCD as an anxiety-related condition, defines it as recurrent obsessions and compulsions that are time-consuming, excessive, and unreasonable.

In dogs, compulsive disorders are described as repetitive behaviors occurring out of context that are not easily deterred or interrupted by normal stimuli. Several behaviors have now been classified as compulsive disorders in dogs, including tail chasing or spinning, fly snapping, air licking, and flank sucking. As in humans, manifestations vary greatly, but differences have been shown in regard to breed-specific dispositions. For example, Doberman pinschers are known to show flank sucking behavior and acral lick dermatitis. German shepherd dogs and Bull terriers seem to be more likely to spin in circles or compulsively chase their tails than dogs belonging to other breeds. Aside from breed predilection, certain families or lines within a breed are more frequently affected. As in humans, as many as 70% of dogs with acral lick dermatitis have comorbid anxiety-related conditions, such as separation anxiety or noise phobia. In some dogs, onset is associated with puberty; others show signs later in life, especially if they are kept under suboptimal conditions or if other environmental factors induce stress.

Dogs are very responsive to intermittent reinforcement schedules, so it is possible that the patient has acquired a learned behavior that may seem odd or unusual. The owner may have inadvertently reinforced the behavior by reacting in a positive or negative manner when the dog displayed it. So-called attention-seeking behaviors are easily mistaken for compulsive behavior problems; however, most attention-seeking behaviors occur exclusively or more intensely during the owner's presence. Stereotypic behavior may also be catalyzed by a need for aerobic exercise or mental stimulation that is not fulfilled under the given housing conditions.

Diagnosis is made on the basis of clinical signs, including the quality and quantity of the repetitive behavior. Consequently, all potential differential diagnoses have to be excluded, beginning with medical/dermatologic conditions (e.g., hypothyroidism, allergies, neoplasia, local pain-inducing conditions).

Acral lick dermatitis is presented as an ulcerative plaque or skin erosion that is self-inflicted by the dog. The surrounding fur is typically stained by saliva. The lesion is commonly found on the dorsal portion of the carpus or metacarpus (unilateral or bilateral) or the dorsolateral tarsus. Secondary infections may cause irritation and require antibiotic treatment.

The diagnostic process includes a complete behavior and medical history, physical examination, complete blood count, serum biochemistry, and thyroid panel. An orthopedic examination and radiographs will exclude local problems. It is necessary to perform a dermatologic workup, including trichogram, skin scraping, and biopsy as well as further diagnostics to rule out allergies and atopic dermatitis.

Treatment of acral lick dermatitis includes behavior modification as well as drug treatment. Owners must avoid unintentionally reinforcing the unwanted behavior. Negative interventions or punishment will at best suppress the frequency of an unwanted behavior if the behavior is disrupted reliably and consistently. Because punishment may increase the fear and anxiety that is already common in animals with compulsive disorders, this approach is not recommended. In other cases, positive punishment (e.g., reprimanding, scolding, pulling the dog away, hitting) may be perceived as attention in response to the behavior, which fulfills the criteria of reinforcement. Instead, owners should reinforce wanted behaviors and apply so-called negative punishment by ignoring the unwanted behavior consistently and actively (turning away or walking away as the dog engages in the behavior). Improvement of suboptimal housing conditions and exercise/activity schedules with interactive play, physical exercise, and learning tasks will enrich the dog's environment and may lead to additional improvement.

Successful treatment of compulsive disorders depends heavily on the use of psychopharmacologic intervention. Drugs, such as clomipramine, have been used for many years. This drug, a tricyclic antidepressant, is not labeled for use in compulsive disorders in the United States, but its efficacy has been reported in several publications. Clomipramine may lower thyroid hormone concentrations and can alter results of thyroid tests. This drug should not be used in dogs treated for hypothyroidism. Newer generation drugs, selective serotonin-reuptake inhibitors such as fluoxetine or fluvoxamine, are used to treat OCD in humans. In companion animals, these types of drugs have also been reported to show good results and fewer side effects (e.g., sedation, anorexia, vomiting, diarrhea, arrhythmia) than tricyclic antidepressants.²

Clients should be aware that initial improvements may take 4 to 6 weeks, and in some cases it may be necessary to try different drugs until the ideal solution is found. Once response is achieved, duration of treatment depends largely on the individual case. When improvement is satisfactory, gradual weaning schedules adapted to the half-life of the drug should be used. It may be necessary to maintain the medication for extended periods or continue it on the minimal effective dosage.

If a dog fails to respond to the drugs used most commonly for the treatment of compulsive disorders, it might be best to consult a veterinary behaviorist to discuss other drugs or combinations of drugs that are currently used on a more experimental basis by specialists.

What to Do
• Confirm diagnosis of acral lick dermatitis by exclusion
• Turn and walk away when dog begins to lick
• Encourage and reward alternative behaviors (not licking/grooming)
• Do not punish or scold
• Improve housing
• Enrich environment with exercise, play, learning activities
• Administer psychotropic drug

In addition:
• Administer antibiotic: Cephalexin (22 mg/kg Q 12 H or Q 8 H for 12 weeks)
• Manage wound (no bandages or Elizabethan collars, if at all possible)