There are several types of "bloat"...........you have frothy bloat also know as Acidiosis and then there is non-frothy bloat.
Frothy comes from diet, ie.......certain types of clover, not properly transitioning cattle from pasture to grain etc., the is very common in feedlots and clover fields. The frothy bloat happens when the cow cannot belch due to blockage in the digestive system caused by frothy fluid forming in the stomach. The cow will become enlarged on the left side and high up into the shoulder.
Non-frothy is generally caused by metals............nails, staple and wire that the cow might swallow which then embeds in the stomach of the cow infecting the cows digestion tract there by preventing the cow from belching.