Sudden cardiac death associated with severe atherosclerosis in a young dog.

A two-year-old female neutered wirehaired Dachshund presented with a four-week history of progressive intermittent pelvic limb weakness, pain and collapse episodes. Serum biochemistry revealed moderate hypercholesterolaemia and hypertriglyceridemia. Electrolytes and haematology were unremarkable. Thyroid and adrenal testing were unremarkable. Initial treatment for suspected spinal disease did not alleviate symptoms. The possibility of cardiac collapse was considered, a 24-h Holter monitor was placed, and additional blood was obtained to assess serum troponin I levels. Further cardiac investigations were declined. While wearing the Holter monitor, the dog collapsed and experienced cardiac arrest, resulting in unsuccessful resuscitation attempts and death. The analysed Holter recording showed bradycardia-induced cardiac arrest, atrioventricular-block, and ST segment depression, suggestive of myocardial infarction or coronary spasm. A postmortem examination showed severe generalised atherosclerosis of the coronary, renal segmental, intervertebral, aorta, carotid, meningeal, and internal thoracic arteries. Severe multifocal myocardial fibrosis and necrosis was noted around the coronary arteries and papillary muscle. As the patient was very young and no other underlying cause was identified, primary hyperlipidaemia (hypercholesterolaemia and hypertriglyceridaemia) was deemed the most likely cause of the severe arteriosclerotic changes leading to sudden cardiac death.