Bloat occurs when rumen gas production exceeds the rate of gas elimination. Gas then accumulates causing distention of the rumen. The skin on the left side of the animal behind the last rib may appear distended. Bloat can be a medical emergency, and timely intervention may be necessary to prevent death. Bloat is a common cause of sudden death in livestock. It usually results from nutritional causes.
There are two types of bloat: frothy and free gas.
Frothy Bloat (pasture bloat)
Frothy bloat is usually associated with the consumption of legumous forages, but may also occur in sheep grazing lush cereal grain pastures or wet grass pastures or consuming grain that is too finely ground. Animals with frothy bloat can be treated with anti-foaming agents such as cooking oil or mineral oil or a commercial product such as Poloxalene.
Free Gas Bloat (feed lot bloat)
Free grass bloat is associated with grain feeding and occurs when animals were not given enough of an adjustment period. Many of the same factors causing acidosis are associated with free-gas bloat. Simple passage of a stomach tube may be effective at relieving free gas bloat. Inserting a trochar or needle into the abdomen is a life-saving procedure that should only be attempted as a last resort.