Long‐term outcome of presumptive idiopathic hyperesthesia syndrome in a dog treated with fluoxetine

Abstract A 9‐year‐old, 10 kg, male, neutered, mixed‐breed dog was evaluated for a history of daily episodes of thoracic and lumbar hair horripilation with potential hypersensitivity and discomfort for at least 1 year, as reported by the owner. Dermatological disease was ruled out. Physical and neurological examinations were normal, and diffuse thoracolumbar disease with intermittent paresthesia was suspected. The main differential diagnoses were syringomyelia/hydromyelia, dynamic radicular compression, or presumptive idiopathic hyperesthesia syndrome. Inflammatory disorders or epileptic seizures with forebrain localisation were considered less likely. The results of spinal cord and brain magnetic resonance imaging examination and a lumbar cerebrospinal fluid analysis were normal. A suspected diagnosis of canine hyperesthesia with an idiopathic origin was made. Oral treatment with corticosteroids and, subsequently, gabapentin did not lead to any improvements. The use of the selective serotonin reuptake inhibitor fluoxetine (at a dose of 2 mg/kg/day orally) led to complete remission of the clinical signs throughout the 4‐year follow‐up.