Lipid storage myopathy in a dog with trismus (locked jaw) and generalised myopathy

Summary

Lipid storage myopathy has been infrequently reported in veterinary medicine, with no reports of trismus. A 3‐year‐old, male, neutered Border Collie dog presented for a 7‐month progressive history of pelvic limb stiffness and trismus. Initial investigations were unremarkable, including magnetic resonance imaging of the vertebral column. At referral to our practice, the dog presented with a 2‐month history of hyporexia and trismus. Complete haematology, biochemistry (including creatine kinase and aspartate transferase), urine analysis and electrophysiological studies were normal. Muscle biopsies revealed excessive intramyofibre lipid droplets within type I muscle fibres. Low total and free plasma carnitine concentrations were identified. Oral supplementation with L‐carnitine and vitamin B complex, alongside intermittent meloxicam and gabapentin, resulted in significant improvement in clinical signs, but moderate trismus and intermittent myalgia were still present. This case report presents a unique clinical presentation for this uncommon myopathy, being the first report of a dog with trismus associated with lipid storage myopathy.