Treatment of phenobarbital overdose by hemodialysis in a cat with suspected porto-systemic shunt

The management of phenobarbital overdose using hemodialysis in a cat with suspected portosystemic shunt is described. An 8 year old British blue intact male cat was referred due to convulsions and stupor. The cat had a lifelong history of abnormal behavior and convulsions every approximately 6 months. The cat was tentatively diagnosed with portosystemic shunt based on high serum ammonia concentrations and abdominal ultrasound. The cat was hospitalized for further diagnosis and treatment, and was accidentally overdosed with phenobarbital at 25 mg/kg IM. Hemodialysis was performed in an attempt to enhance clearance of the drug. Phenobarbital levels decreased gradually during the treatment, however, there was no improvement in the neurological status of the cat and the owners elected euthanasia. To the best of the author’s knowledge, this is the first report demonstrating the utility of hemodialysis in the management of phenobarbital overdose in small animals.