Survey Results: How Veterinarians Prescribe Fluoxetine for Dogs and Cats

Veterinarians use fluoxetine to treat a wide variety of behavior disorders in dogs and cats, according to the results of a 2013 survey published in Veterinary Record Open. Most survey respondents prescribed fluoxetine to be given once daily. Those who treated both dogs and cats with fluoxetine usually prescribed a generic formulation, and those who prescribed it only for dogs generally used a product approved for use in dogs by the US Food and Drug Administration (FDA).

Fluoxetine hydrochloride, a selective serotonin reuptake inhibitor, is a psychotropic drug used to treat behavior disorders in humans and veterinary patients. A veterinary formulation of fluoxetine (Reconcile, Elanco Animal Health) was approved by the FDA in 2007 to treat canine separation anxiety together with behavior modification therapy. Reconcile is approved for use only in dogs, not in cats, and its labeled dosage schedule is once a day.

Investigators from Western University of Health Sciences College of Veterinary Medicine (Pomona, California) performed the survey to identify small-animal veterinarians’ prescribing habits for fluoxetine. The authors note that studies of off-label veterinary use of fluoxetine and the dosage schedules prescribed by veterinarians have not been conducted. “This study is an initial step in investigating the use of psychopharmacological drugs in veterinary behavior medicine,” they write.

The investigators recruited survey participants by email and at local veterinary meetings. They received 127 completed surveys from small-animal veterinarians in the United States and Canada.

Most respondents (83%) said that they treated dogs, cats, or both with fluoxetine. Of these, 91% prescribed once-daily dosing. Nearly two-thirds (61%) of the veterinarians who prescribed fluoxetine once daily did not specify a time for the drug to be given; 36% specified that it should be given in the morning.

Formulations prescribed by survey respondents were generic versions, compounded (not generic) formulations, Reconcile, and Prozac (approved by the FDA for use in humans and manufactured by Eli Lilly, the parent company of Elanco). Of the 60 practitioners who used fluoxetine for both dogs and cats, 48 (80%) prescribed the generic version. Most veterinarians who reported using fluoxetine only for dogs prescribed Reconcile (23 of 33, 72%). Thirteen practitioners prescribed fluoxetine only for cats; of these, 7 (58%) used a generic version and 5 (42%) used a compounded formulation.

Participants identified 32 behaviors for which they prescribed fluoxetine in dogs. The investigators classified these behaviors into five categories:

• Anxiety
• Aggression
• Compulsive disorders
• Phobias/fear
• Other

Anxiety was by far the most common behavior category for which veterinarians prescribed fluoxetine for dogs. Behaviors falling into the “other” category included “behavioral issues,” chronic lick granuloma, destructive behavior, hyperactivity, allergy, and excessive barking.

The respondents listed 22 indications for which they prescribed fluoxetine in cats. The authors organized these behaviors into six categories:

• Elimination behaviors
• Anxiety
• Aggression
• Dermatologic/grooming behaviors
• Compulsive disorders
• Other

Elimination behaviors were the most common reason respondents prescribed fluoxetine to cats. Behaviors in the “other” category included “behavioral issues,” pica, and tail chasing.

The investigators asked survey participants the year they graduated from veterinary school and examined prescribing differences between the 69 respondents who graduated before 2007 (the year Reconcile was approved) and the 35 who graduated in 2007 or later. The results showed no significant differences between groups in dose frequency, dosing schedule, formulations prescribed, or species treated with fluoxetine.

The authors conclude that survey respondents prescribed fluoxetine for many behavioral problems in dogs and cats, most commonly using generic formulations and once-daily dosing. “Widespread off-label use of fluoxetine for behavioral disorders highlights the need for research, academic education and continuing education of veterinarians regarding animal behavior and psychopharmacology,” they write.

The authors listed several study limitations, most notably the use of convenience sampling. Because some veterinarians who did not prescribe fluoxetine chose not to participate, the results could have overestimated practitioners who did prescribe the drug. In addition, the sample size was small. Manufacture of Reconcile was discontinued in the United States two months after the six-month study period began, and the investigators did not know how many respondents had Reconcile in stock at the time of the survey.

The authors note that this survey did not address adverse effects, dosages, or behavioral modification techniques used along with fluoxetine administration. However, they write, the study can be used as a baseline for further investigation.

The study was funded by Western University of Health Sciences.

Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is also a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC. She works as a full-time freelance medical writer and editor and continues to see patients a few days each month.