Horses that develop long-term difficulty with colon ulcers may have more than one factor operating, as well as more than one cause. It pays to understand what may cause these ulcers and to learn to recognize the symptoms early on.
The symptoms of colonic ulcers are varied and depend on both the duration and severity of the problem. The most common sign, and the one that is most likely to get your attention, is repeated bouts of abdominal pain.
Rectal examinations typically don't reveal any helpful findings, and many cases are diagnosed as spasmodic/gas colics or possible mild impactions, and may be tubed with mineral oil, treated for a while with Banamine and recover, only to do it again. Aggressive deworming may be tried to no avail. Gastric ulcers may be suspected, may even be found on endoscopy, but treatment for this doesn't resolve the problem either. If the horse has progressed to the point where he's losing enough blood protein (albumin) through the ulcerated areas and this is picked up on a serum chemistry, focus may be directed to the liver, particularly if there is any mild elevation of liver enzymes, but this isn't the problem either. It may take several vets before you find one that has dealt with the problem, recognizes the symptoms and runs the right tests, or the horse may actually end up in surgery before a diagnosis is made.
Directly examining the horse's stomach is a lot simpler matter than getting a look at his colon. The large and small colon combined are about 25 feet long. Physical examination and rectal examination may not reveal much more than some increased gas. Short of opening the horse surgically to get a look and do biopsies, diagnostic techniques were largely limited until recently. In 2003, clinicians from the North Carolina State College of Veterinary Medicine published information on using ultrasound to diagnose right dorsal colitis. Because the colon lies close to the body surface, it is easily imaged using ultrasound and a thickened, inflamed wall can be seen. Another test is intravenous administration of radioactively labeled albumin. The manure is then tested to see how much passes into the intestinal tract.