Fluoxetine. Fluoxetine, a selective serotonin reuptake inhibitor, may also be useful in treating repetitive surface licking behavior. It has fewer effects on other neurotransmitters than do other antidepressants, such as the tricyclic antidepressants, so it may have fewer side effects.¹⁹ Similar to clomipramine, fluoxetine has been shown to be effective in treating canine compulsive disorders²⁰ as well as other anxiety-related disorders in dogs and cats.¹⁹ In one study in dogs receiving fluoxetine, the adverse events were limited to lethargy and decreased appetite, and no side effects were severe enough to warrant discontinuing the medication.²⁰

The recommended dosage for fluoxetine in dogs is 1 to 2 mg/kg administered orally once daily.¹⁹ Fluoxetine may affect blood glucose concentrations, so diabetic patients should be monitored carefully while receiving this medication.¹⁹ As with clomipramine, never give fluoxetine with monoamine oxidase inhibitors, and use caution when giving fluoxetine or clomipramine to patients with existing renal or liver failure.^18,19

Duration of drug therapy. More information about the safe and appropriate use of the psychotropic drugs can be found in the text Veterinary Psychopharmacology. Remind clients that while some anxiety-related disorders might respond to pharmacologic intervention within a few days or weeks, compulsive disorders might respond much more slowly. An owner should be prepared to treat for a minimum of four to six weeks before deciding if improvement is noticeable.¹⁰ If the medication appears to be helping, continue treatment for at least one or two months after the cessation of the clinical signs and then gradually taper the dosage and stop the drug if signs do not reappear during dosage reduction.² Some patients with compulsive disorders will always require medication to maintain remission, especially if the causal factors cannot be identified and changed.

A dog's excessive licking of surfaces is most likely a result of a medical condition leading to nausea or gastrointestinal distress. It may occasionally be a result of anxiety or conflict leading to displacement behaviors and eventually an actual compulsive disorder. An accurate diagnosis will require excellent history-taking skills and patience on the part of the clinician and dog owner. If the cause is determined to be primarily behavioral, treatment includes attention to the dog's environment and behavior modification in addition to pharmacologic therapy. Pharmacologic therapy is not as likely to be effective without behavior and environmental modification, and remission is likely when the drug is discontinued if causative factors have not been identified and changed.

Valarie V. Tynes, DVM, DACVB
P.O. Box 1040
Fort Worth, TX 76101