Cardiac toxicity from phenylpropanolamine overdose in a dog.

A 5-year-old, 29-kg, female Labrador retriever developed tachypnea, tachycardia, and ataxia following ingestion of approximately 48 mg/kg of phenylpropanolamine. Initial diagnostic tests showed multiform ventricular tachycardia, left ventricular dilatation with a focal dyskinetic region in the dorsal interventricular septum, and elevations in creatinine kinase and cardiac troponin I. All abnormalities resolved within 6 months. The transient electrocardiographic, echocardiographic, and biochemical abnormalities were consistent with myocardial necrosis from infarction or direct catecholamine-induced myocardial toxicity.