Rhabdomyolysis and myoglobinuric acute renal failure (capture myopathy) in a stranded striped dolphin (Stenella coeruleoalba) in the Canary islands

Abstract

An adult male striped dolphin was found stranded alive on the coast of Fuerteventura. The animal had a good body condition and presented a rostral mandibular fracture attributed to a fishing interaction, which was considered the cause of the active strand. The animal was kept in a small private swimming pool and transported by car and helicopter to Gran Canaria dying 48 hours after the stranding. During necropsy, no relevant gross lesions were detected and tissue samples were collected for histopathological examination. An immunohisthochemical study was performed using anti-fibrinogen and myoglobin as primary antibodies. Histologically, the main lesions were related to skeletal and cardiac muscle and kidneys. Muscular lesions were characterized by hyaline change in segments of fibers with no inflammatory response. Degenerated fibers did not present striations using PATH stain, and immunohistochemically showed complete depletion of myoglobin and a strong, diffuse, intracytoplasmatic immunorreaction for fibrinogen was detected. Renal lesions consisted with severe swelling of tubular cells and the presence of pigmented orange granules both in cells and in homogenous casts, which occupy the tubular lumen. Granules and casts presented in the lumen and in the cytoplasm of renal tubules were strongly immuno-labelled by myoglobin. Capture Myopathy is an acute myopathy characterized by rhabdomyolysis and acute tubular necrosis described in wild animals following a chase, a struggle or transport. Trauma, excessive muscle activity and prolonged muscle compression during the fishing interaction, the active stranded and the transport were considered the most probable origin of the muscle necrosis in this case. This disease should be included in the differential diagnostic of acute death in active stranded cetaceans, emphasizing the importance of an exhaustive examination of skeletal muscle in order to find degenerative changes and the usefulness of fibrinogen and myoglobin as markers of early ischemic muscle damage and myoglobinuric renal failure in dolphins.