Horses are vegetarians, and most of them pass gas on a regular basis in the process of digesting their food. Excessive flatulence can occur when food is not digested within the stomach and ferments within the large intestine or caecum.
Flatulent colic is commonly found in horses that are eating large quantities of fermentable food such as rich spring grass or hay. These foods cause the "flora," or healthy bacteria, population within the horse's intestine to change, stimulating increased production of gas. Flatulent colic causes mild to severe abdominal pain. Horses sometimes can be encouraged to pass gas with controlled exercise such as walking and slow trotting.
Causes of colic include stress, impaction, sand and strangulation. If you put your ear against your horse's belly, you can listen for gut sounds. A horse with an impaction or twisted intestine will have little or no gut sounds. High-pitched gurgles are commonly associated with flatulent colic.
If a horse has colic, a veterinarian will tube the horse with mineral oil and give it an anti-inflammatory drug such as Banamine.