Also known as TYMPANY this condition occurs in cattle and sheep, but is more common in cattle. When animals digest food, gas is produced in the rumen. This is normal and the cow gets rid of the gas by frequent belching, made possible by rumen contractions. If the gas builds up faster than the cow can get rid of it, the rumen swells up, may become paralysed and presses up against the lungs, causing eventual death by suffocation. The cause of this sudden gas build up is usually excessive starch and often seen when animals are grazed on young green fast growing lucerne or clover. If the bubbles of gas are large and sit above the food, the bloat is normally fairly easy to treat. However, if the surface tension of the gas bubbles is low, the bubbles are small and mix up with the food. This is the condition known as “frothy bloat” and is much more difficult to treat.
• Visible swelling of the rumen (see picture)
• Bloat can be a secondary symptom of another condition eg a physical obstruction in the oesphagus, or extremely swollen lymph glands eg with tuberculosis.
In mild cases, walking the animal for 30 minutes will often encourage the belching reflex and the animal will release the gas build up.
If there is no response in 30 mins the animal should be drenched with a treatment designed for relief of bloat (BLOATGUARD DRENCH) or with liquid turpentine.
If this is not effective and as a last resort, the rumen has to be pierced with a trochar and canula and the gas released. The trochar is inserted into the left side of the animal, in the centre of the rumen, a space equidistant to the last rib, the hip and the vertebrae of the spine. Drench can be inserted into the rumen through the trochar to increase surface tension and help the gas bubbles to burst. Relief should be rapid.
• Feeding roughage such as dry hay before turning animals onto new young grazing
• Feeding starchy foods eg concentrates at least 2 hours before turning animals onto Lucerne or clover
• Lucerne should be cut and wilted for 24 hours rather than allowing animals to graze.