Progressive increases in creatine kinase activity in an anorexic cat with necrotising myopathy

CASE SUMMARY: A 5-year-old castrated male domestic shorthair cat with weight loss and reduced appetite was evaluated for increased and progressively rising creatine kinase (CK) activity. The cat had recently been diagnosed with hepatic lipidosis. Muscle biopsy and histopathology revealed mild myonecrosis and phagocytosis without obvious inflammatory cell infiltrates. Resolution of necrotising myopathy was observed after a short course of anti-inflammatory prednisolone and nutritional supplementation. RELEVANCE AND NOVEL INFORMATION: This is the first report of a necrotising myopathy in a cat associated with progressively increasing CK activity and decreased appetite. Anorexia in cats has been associated with increased CK activity, but an underlying cause of this CK elevation has only been postulated. Here we document muscle necrosis and muscle stiffness in a cat with anorexia.