Fluoxetine for Behavior Disorders in Dogs

In the Literature

Chutter M, Perry P, Houpt K. Efficacy of fluoxetine for canine behavioral disorders. J Vet Behav. 2019;33:54-58.

The Research …

Behavior problems in dogs are common, with ≈85% of dogs in the United States affected.¹ Fluoxetine is commonly used in the treatment of these disorders.^2-4

In this retrospective study, the records of 88 dogs were analyzed. Dogs given a behavior modification plan and prescribed fluoxetine were included. Some were treated with an adjunct medication in addition to fluoxetine. Owners were surveyed on the effects of fluoxetine for up to several years after their dog began treatment. Fluoxetine doses varied and were grouped into ranges (ie, 0-0.49 mg/kg, 0.5-0.99 mg/kg, 1-1.49 mg/kg, 1.5-1.99 mg/kg, and ≥2 mg/kg PO every 24 hours). Thirty-nine dogs received only fluoxetine as a pharmaceutical treatment; of these, 59% responded positively and 10% responded negatively. Best responses to fluoxetine were seen with dosages between 0.5 and 1.49 mg/kg PO every 24 hours. The lowest response rates were seen with dosages between 1.5 and 1.99 mg/kg PO every 24 hours. Dogs receiving higher dosages (≥1.5 mg/kg PO every 24 hours) were more likely to show negative signs. Dogs that received trazodone or clonidine in addition to fluoxetine represented the highest percentage of positive responses.

This study had several limitations. Results were based on owner reports provided up to several years after treatment was initiated. Dogs treated with fluoxetine alone were included with dogs treated with adjunct medication (ie, clonidine, trazodone), and there was no control group. All owners were given a behavior modification plan; however, the authors did not follow up on the level of compliance with that plan. Implementation of a behavior modification plan can significantly affect owner perception and objective outcomes.

… The Takeaways

Key pearls to put into practice:

• As with other selective serotonin reuptake inhibitors, the response to fluoxetine is often dose dependent; however, dosages >1.5 mg/kg PO every 24 hours do not always yield a positive response and are more likely to produce adverse effects.

• The best response may be achieved by using an adjunct medication in addition to fluoxetine.

• A reasonable expectation of improvement (ie, ≈60%) can be expected when fluoxetine is used in conjunction with a behavior modification plan.