Acute neurological and cardiac sequelae of a canine hypothyroid crisis

ABSTRACT A 4‐year‐old mixed‐breed dog presented with acute circling, restlessness, and inappropriate mentation. Bloodwork revealed a marked hypertriglyceridaemia and hypercholesterolaemia, as well as a severely elevated creatine kinase. A thyroid panel was consistent with hypothyroidism. During hospitalisation, the dog developed ventricular arrhythmias requiring the use of antiarrhythmic therapy. It was also treated with injectable levothyroxine, fenofibrate and a heparin continuous rate infusion. Its neurological signs rapidly improved over 4 days of in‐hospital treatment, and by 6 weeks after discharge, there was only a mild residual vestibular ataxia. Given its rapid improvement, a cerebrovascular event (likely thromboembolic) was suspected to be the cause of its acute neurological signs. This case report is the first to describe the combination of severe hyperlipidaemia, severe creatine kinase elevation, central vestibular neurological deficits and ventricular tachyarrhythmias associated with a hypothyroid crisis in a dog.