CASO CLÍNICO: BROTE DE ENFERMEDAD DEL MÚSCULO BLANCO O MIODEGENERACIÓN NUTRICIONAL EN TERNEROS Clinical Case: Outbreak of White Muscle Disease or Nutritional Muscular Dystrophy in Calves

An outbreak of White Muscle Disease, WMD, or Nutritional Muscular Dystrophy is reported in a flock of 56 Red Friesian calves, where 18 calves of 4 to 5 months of age died in a pe- riod of 45 days. The signs observed were tachypnea, difficulty to walk, tachycardia, dilated jugular veins, temperature 38- 39°C. Signs of alterations of the nervous or digestive systems were not observed. Muscles of the hind legs, dorsal and gluteal region were moderate swollen, painful and temperature was in- creased. In the flock sudden deaths of calves were observed within a few hours after appears the first signs. The blood ac- tivity of the selenium (Se) dependent enzyme Glutation peroxi- dase (GSH-Px) was decreased, indicating a Se deficiency. The serum activity of the enzymes associated to muscle damage, Aspartate Amino Transferase (AST) and Creatin Kinase (CK) were increased. The necropsy findings were cardiac enlarge- ment with hypertrophy of the right ventricle. In the myocardium white fine lines of degeneration and also multiple irregular ar- eas with the same colour were observed. Similar lesions were observed on the skeletal muscles. Histologically the myocar- dium lesions were eosinophilic and irregular muscular cells, with lost of the striation, segmental destruction, as well as great and pleomorfic nuclei; in addition, the Purkinje fibres pre- sented intense eosinophilia and hyaline degeneration corre- sponding to degeneration of Zenker. The skeletal muscles also presented hyaline degeneration of Zenker. It is concludes that it is White Muscle Disease associated to deficiency of Sele- nium or vitamin E. Surviving calves were treated with an intra- muscular solution of Se and vitamin E, in dose equivalent to 8 mg of Se and 340 U.I. of vitamin E. The treatment was re- peated after 7 days and new cases did not appear.