Clinical, biochemical and pathological studies of adult buffalo calves at Basrah, Iraq were conducted on 64 suspected calves with muscular dystrophy, and other 10 clinically healthy animals was served as controls. Suspected calves have a history of recent turnout of exercise and reared in lush green grazing areas. Diseased calves showed different clinical signs, include sudden onset of dullness, Loss of appetite, lateral recumbence and difficulty to rise , panting with mouth breathing, Irregular heartbeats on auscultation, and acute death within 24hrs. However, Macrocytic normochromic anemia was detected by the hematological examinations. A significant hypo -thrombocytopenia and a significant difference of clotting factor indices were also indicated. Moreover, the results of the biochemical changes showed a statistically significant decrease (P<0.05) in α-tocopherol, Glutathione peroxidase, Whereas, a significant increase (P<0.05) in the values of Aspartate aminotrasferase (AST), Creatine kinase(CK) and Troponin I in the diseased animals than controls has been indicated. The cross pathological results of carcasses indicated enlargement of the heart which appears spherical-like in shape. There were small white patches on the epicardial surface. However, petechial hemorrhages on the epicardial surface were also indicated. The histopathological findings revealed mild to severe diffuse vacuolar changes (degeneration) in the myocardial fibers, a thrombotic mass revealed to inflammatory cell infiltration, and areas of severe fibrosis accompanied by inflammatory cell infiltration which revealed to interstitial diffuse fibro-myocarditis was also detected. It was concluded that acute dystrophy of cardiac muscles has a harmful effect on diseased calves mostly terminated with sudden death.