Cyanide intoxication in sheep: therapeutic value of oxygen or cobalt

The combination of cobalt salts and oxygen with the traditional sodium nitrite-sodium thiosulfate antidote may have value as cyanide antidotes. Results reported previously in mice were extended to sheep in the present experiments. Cobaltous chloride (15 mg/kg of body weight) or oxygen with or without sodium nitrite and sodium thiosulfate were compared with respect to the median lethal dose of oral sodium cyanide. Although cobaltous chloride or oxygen used alone did result in a significant increase in the median lethal dose of sodium cyanide in sheep, the protection was minor compared with the overall protection provided by the classic antidotal combination of sodium nitrite and sodium thiosulfate. Cobaltous chloride combined with sodium nitrite and sodium thiosulfate did not provide any increase in protection more than that observed with sodium nitrite and sodium thiosulfate alone. Oxygen used in combination with sodium nitrite and sodium thiosulfate did significantly increase the protection. However, the increase in protection was not of sufficient magnitude to recommend it as a practicable addition to the present therapeutic regimen.