Generalized Anxiety Disorder (GAD) in a teaching laboratory beagle: Presentation, relative contributions, and treatment

Abstract

A 4-year-old, female, spayed beagle—adopted from a veterinary school teaching beagle program—presented for behavioral reactivity toward dogs on walks and environmental noises, and repetitive locomotory behavior. Following medical and behavioral assessment, she was diagnosed with Generalized Anxiety Disorder (GAD) with secondary noise reactivity. Initial treatment included clomipramine (Clomicalm; Virbac) (20 mg Per os (PO) q. 12 hours; 2.5 mg/kg) and gabapentin (200 mg PO q. 12 hours; 25 mg/kg) with behavioral and environmental modification. After two months without improvement, clomipramine was switched to citalopram (5 mg PO q. 24 hours; 0.6 mg/kg), and alprazolam (0.25 mg PO q. 12 hours; 0.03 mg/kg) was added with continued gabapentin. During treatment, suspected seizure events occurred. Following consultation and diagnostics with an internal medicine specialist, a tentative diagnosis of idiopathic epilepsy was made, and phenobarbital was initiated (22.5 mg PO q. 12 hours; 2.88 mg/kg). Due to phenobarbital-induced cytochrome P-450 enzymes interacting with alprazolam, a regression of behaviors occurred and new abnormalities (anxiety when separated) developed. Alprazolam was increased (0.375 mg PO q. 12 hours; 0.05 mg/kg) to overcome this; however, this induced paradoxical adverse effects, namely aggression toward the housemate dog. After discussion with a consulting neurologist, phenobarbital was discontinued, and alprazolam was lowered to the original dose. Following 6 months of treatment with citalopram, gabapentin, alprazolam, and situational Sileo (Zoetis) (1 dot [0.25 ml @ 0.1 mg/ml = 0.025 mg] 20-30 minutes prior to walks), with behavior and environmental modification, the patient improved with reduced reactive and anxious behaviors.