Bloat

Abstract

Most cases of bloat are caused by a stable foam which covers the cardia of the stomach. Dougherty and Habel demonstrated in 1955 that the cranial esophageal sphincter would not permit foam to escape into the pharynx, thus blocking eructation when foam fills the esophagus (1). The observation that some bloated ruminants have a cap of free gas in the rumen and can be "Let down" with a stomach tube or trocar does not preclude the fact that a stable foam covers the cardia of the stomach (2).

Not all bloat is caused by a stable foam. Other causes are vagal nerve damage, esophageal obstruction, pressure on the esophagus as from a tumor, factors that interfere with eructation such as pneumonia or diphtheria, alkalosis as from urea (ammonia) poisoning, founder, cyanide and hydrogen sulfide poisoning.