Acute selenium toxicosis in sheep

Acute selenium (Se) toxicosis was evaluated in 20 female crossbred sheep, 8 to 14 mo of age. Five groups of 4 sheep each were given 0.4, 0.6, 0.7, 0.8, or 1.0 mg Se/kg body weight IM. The LD50 for sodium selenite was 0.7 mg Se/kg body weight with a standard error of 0.035 over a 192 hr observation period. The most evident clinical signs were dyspnea and depression. At necropsy, the most consistent lesions in animals which received 0.7, 0.8, and 1.0 mg Se/kg body weight were edematous lungs and pale mottled hearts. Highest tissue Se concentrations in declining order were found in the liver, kidney and heart.