Adult-Onset Muscular Dystrophy in a Cat associated with a Presumptive Alteration in Trafficking of Caveolin-3

A 10-year-old neutered female domestic longhaired cat was referred for evaluation of forelimb weakness and lameness. There was hypertrophy and firmness of the musculature with no neurological deficits. Moderate increase of creatine kinase activity was present. Muscle biopsy showed rounded atrophic and hypertrophic fibres, an increased number of centrally located myofibre nuclei, scattered rimmed vacuoles and mild perimysial and endomysial fibrosis. Myofibre necrosis with phagocytosis was present in the gluteal muscle. Immunohistochemistry revealed absence of sarcolemmal caveolin-3 in almost all muscle fibres and sarcoplasmic accumulation of the protein in approximately 30% of myofibres. Normal expression of caveolin-3 was detected by immunoblotting, so protein mislocalization in the sarcoplasm due to aberrant trafficking towards the sarcolemma was suspected. This case represents the first example of muscular dystrophy due to a caveolinopathy in animals.