Abstract
Endotoxin from Salmonella typhimurium was administered intravenously to 3 cows. It produced an immediate increase in blood prostaglandin metabolite levels causing either luteolysis or a temporary drop in progesterone concentrations depending on the degree of prostaglandin synthesis. The clinical effects on heart rate, respiratory rate, ruminai contraction rate, body temperature and other general signs were studied. The cows showed a transient increase in heart and respiratory rate and a decrease in ruminai activity. The temperature responded by a small initial decrease and a secondary increase. Other symptoms included muscular weakness and shivering, excessive salivation and diarrhoea. Plasma Ca levels showed a direct decrease and then slowly increased to initial levels in the course of several days. The role of endotoxins in Gram-negative infections and their mode of action on the body are discussed with special emphasis on the role of prostaglandins on reproductive function.