Transient echocardiographic and cardiovascular changes temporally associated with trazodone administration in a geriatric dog.

A 14-year-old neutered male Toy Poodle was presented for elective bilateral phacoemulsification surgery. After initial physical examination at the hospital, oral trazodone (5 mg kg-1) was given approximately 2 hours before anaesthesia to facilitate preoperative handling. Approximately 1 hour after trazodone and before anaesthetic premedication, a previously undocumented grade 3/6 left apical systolic heart murmur was auscultated during repeat physical examination. Focused echocardiographic assessment revealed subjectively reduced left ventricular internal dimensions with an appearance suggestive of concentric hypertrophy. No overt clinical evidence of dehydration was identified, although serum biochemistry revealed a mild increase in symmetric dimethylarginine concentration (16 μg dL-1; reference interval 0-14 μg dL-1). Elective anaesthesia and surgery were postponed, and the dog was hospitalised overnight for intravenous fluid therapy. Repeat cardiovascular assessment approximately 22 hours after the initial trazodone dose revealed resolution of the heart murmur and normal left ventricular internal dimensions on echocardiography. Similar cardiovascular findings did not recur after subsequent trazodone dosing under conditions of improved intravascular volume. This case describes transient cardiovascular changes temporally associated with trazodone use in a geriatric dog undergoing preanaesthetic assessment and highlights the potential influence of intravascular volume status on interpretation of cardiovascular findings.