1. It has been shown that turpentine and two proprietary coal-tar
preparations have little or no inhibitory action on gas formation in ruminal
ingesta incubated in vitro when added in therapeutic concentrations.
2. Very small concentrations of these substances have a marked effect
on the physical consistency of the ingesta, raising surface tension and
breaking down foam.
3. This affords evidence that it is by their physical action on surface
tension that these drugs exert their undoubted beneficial effect in acute
4. The "foam theory" of the pathogenesis of bloat is discussed.
5. Formalin and copper sulphate may have some inhibitory action on
gas formation but the use of ruminal disinfectants cannot be recommended.