Acid pain

THE equine stomach is single chambered, with the top third covered by a white squamous mucosa and the bottom two-thirds covered by a pink glandular mucosa (see image, far right).

Equine gastric ulceration syndrome (EGUS) has two forms: equine squamous gastric disease (ESGD), which is caused by increased acid in the stomach directly injuring the squamous tissue; and equine glandular gastric disease (EGGD), which is caused by failure of the glandular tissue’s defensive mechanisms (mucus, bicarbonate and blood flow) against stomach acid.

Horses produce stomach acid continuously, but the amount produced increases during eating and during exercise. The pH of the squamous mucosa in horses with free access to feed follows a 24-hour rhythm, being neutral in the day (as the horse eats) and acidic at night (as the horse sleeps and the stomach contents empty into the small intestine). The main risk period for ESGD is therefore increased