Centronuclear myopathy in a Labrador Retriever presenting for evaluation of a ‘bunny‐hopping’ gait

Abstract

A 3‐year‐old female neutered Labrador Retriever presented with a chronic history of ‘bunny‐hopping’ gait, presumed secondary to hip dysplasia. They exhibited moderate exercise intolerance, developing a stiff, short‐strided gait and collapsing into sternal recumbency after a brief period of exercise. Physical examination identified crepitus upon abduction of the left hip. Neurological examination at rest identified absent patellar reflexes, with repeat examination at the time of collapse identifying concurrently reduced withdrawal reflexes in all limbs that spontaneously resolved over a short period of time. A neuromuscular localisation was made. A conscious thoracic radiograph and clinical pathology (including measurement of creatine kinase and aspartate aminotransferase), were normal. An electrodiagnostic study identified spontaneous activity on electromyography coupled with normal nerve conduction studies and repetitive nerve stimulation, consistent with a myopathy. Genetic testing identified a homozygous mutation of the protein tyrosine phosphatase‐like A (PTPLA) gene, causative of centronuclear myopathy.