Polioencephalomalacia was diagnosed in two sheep, one goat and two cows. These animals were in differe nt ages. Clinical signs of affected animals were central blindness, tremor, muscular spasms specially in limbs, recumbency, clonic convulsion, opisthotonus, nystagmus and hypersensitivity to sounds and touch. Treatment was performed by administration of thiamin hydrochloride and dexamethasone. Two affected cows recoverd following treatment but sheep and boat died. Histopathological study on brain sections of died animals reveald laminar degeneration of neurons with ischemic changes in cerebrum, congestion of meninges, perivascular and perineuronal edema, liquifaction necrosis of cerebral panrenchyma, necrosis of neurons and microgliosis. Affected sheep and goat did not respond to treatment because of development and progression of brain lesions.
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