Progress in the prevention of acute bovine pulmonary emphysema

Abstract

The control of pulmonary emphysema by management techniques, the effectiveness of drugs and the possibility of preventing ruminal production of 3-methylindole (3MI), which causes the disease, are discussed. In vitro studies on rumen fluid showed that several compounds (Desoxysalinomycin, X-206Na, chloral hydrate, nigericin, lasalocid, monensin, narasin and salinomycin) effectively inhibited conversion of L-tryptophan to 3MI. In a field trial, rumen production of 3MI in 10 cows given daily doses of 200 mg of monensin was compared with 3MI production in 10 cows, on the same pasture, given placebos. Mean levels of 3MI in monensin treated cows was less than half that in cows given placebos after 144 h and was less than a third after 216 h. Although neither group developed pulmonary emphysema results suggest that monensin may be effective in preventing the disease. However, food and drug regulations in the USA prohibit the use of monensin in breeding stock.