Dystrophin-Deficient Muscular Dystrophy in an Australian Cattle Dog (Blue Heeler)

X-linked dystrophin-deficient muscular dystrophy is associated with a mutation of the DYS gene located on the X chromosome. To date, dystrophinopathy has been identified in 16 different dog breeds with 20 different variants confirmed. In this report, a 9 mo old male Australian cattle dog was evaluated for progressive generalized weakness and dysphagia beginning at 4 mo of age. A markedly elevated creatine kinase activity was noted on blood chemistry, and muscle biopsies confirmed a dystrophic phenotype. Dystrophin deficiency was identified by immunohistochemistry. In this report we identify dystrophin-deficient muscular dystrophy for the first time in a 9 mo old intact male Australian cattle dog. This finding expands the list of breeds confirmed with dystrophinopathy. Whole-genome sequencing is required to identify the causative mutation.