Behavioral Therapy and Fluoxetine Treatment in Aggressive Dogs: A Case Study

SIMPLE SUMMARY: Despite dog aggression representing a frequent and serious threat to public health, currently there are no licensed drugs for treating dog aggression. Treatment approaches include behavior management programs and empiric administration of fluoxetine for extended periods. The drug is used at 1–2 mg/kg of body weight every 24 h according to the clinician’s prescription. Studies concerning long-term dosage schedules and the effects of fluoxetine on clinical and blood parameters have not been undertaken in veterinary medicine. In the present study, fluoxetine (1.5 mg/kg/die PO) combined with a behavior modification program were used for treatment in eight dogs with a diagnosis of dominance-related aggression. Clinical outcomes for fluoxetine, norfluoxetine, and serotonin circulating levels were periodically evaluated over a six-month period. After one month of treatment, significant clinical improvement was observed, although dogs were classified as fully responsive starting from T2 (two months of treatment). At the end of the follow-up (six months of treatment), a correlation between norfluoxetine levels and clinical scores (r = 0.75, p < 0.05) was observed. Blood serotonin levels were significantly decreased. The results suggest that the dosage schedule is useful in the management of dominance aggression in dogs and that norfluoxetine levels seem reliable in predicting clinical efficacy. ABSTRACT: Canine aggression is a major concern, affecting millions of people worldwide, and treatment can be challenging even for skilled veterinarians. Empiric use of fluoxetine is sometimes attempted, although few data regarding long-term effects in aggressive dogs are available. The aim of the study was to investigate clinical effectiveness of fluoxetine (1.5 mg/kg/die PO) combined with a behavior modification program for treatment of canine dominance-related aggression. Circulating levels of fluoxetine, norfluoxetine, and serotonin (5-HT) were also measured. Eight dogs with a diagnosis of dominance aggression (owner-directed) were enrolled. Before treatment (T0), and after one (T1), two (T2), four (T3), and six (T4) months of fluoxetine administration, clinical outcomes were graded using a five-point frequency scale (0–4), and blood samples were collected to measure fluoxetine/norfluoxetine (high-performance liquid chromatography) and 5-HT (ELISA) levels. Following treatment, a decrease in behavioral test scores was observed at T1–T4. Increasing concentrations of circulating fluoxetine and norfluoxetine were measured throughout the follow-up. Correlation between norfluoxetine levels and clinical scores was observed at T4. Starting from T1, a significant decrease in 5-HT levels was observed. Our data suggest that fluoxetine (1.5 mg/kg/day) when associated with behavior treatment is effective in controlling canine aggression over a six-month period, and that, in dogs norfluoxetine levels seem reliable in predicting clinical efficacy.