Effect of fluoxetine at a dosage of 2-4 mg/kg daily in dogs exhibiting hypersensitivity-hyperactivity syndrome, a retrospective study

Abstract

Hyperactivity in dogs is discussed as being increasingly linked with human Attention Deficit Hyperactivity Disorder. The French veterinary psychiatry community has proposed a precise definition of an Attention Deficit Hyperactivity Disorder -like syndrome in dogs called Hypersensitivity-Hyperactivity syndrome (HSHA). Dogs suffering from severe HSHA present 3 main symptoms: hypermotricity, lack of satiety, and shorter sleep duration with normal cycles. Because these symptoms suggest involvement of the serotonergic pathway, fluoxetine is the main medication proposed by the French veterinary psychiatry community to treat these dogs. We present the results of a retrospective study of dogs suffering from severe HSHA syndrome and treated with fluoxetine at dosages of 2 mg/kg/day and above. Ninety-eight dogs’ file were studied with the help of 23 French veterinary behaviorists and 89 dogs were included in the final sample. The 3 main symptoms of severe HSHA and 5 main adverse effects were evaluated according to the dog's file at the first consultation and at a follow-up 4-8 weeks later. Eighty-eight dogs showed at least some degree of improvement. Improvement was quite high or perfect for 48 of the 89 dogs in motricity, 63 of the 89 in sleep, and 44 of the 89 in satiety. Fifty-four of the 89 dogs (61%) showed adverse events at various levels, with very few dogs experiencing severe adverse effects. In 6 cases the dosage was reduced due to adverse effects but remained at least 2mg/kg. Given the positive reactions to the treatment within our sample, fluoxetine at a dosage of 2-4 mg/kg PO q. 24 hour may be considered as a safe and effective treatment for some dogs suffering from severe HSHA. Further prospective studies also using a lower range of dosages are required for validation.