Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Clostridial, Clostridium Colitis (in Adult)


Colitis in the adult horse is a challenge to definitively diagnose and often costly to successfully treat. It is also a difficult disease to explain to horse owners.

Colitis is inflammation of the large colon, the lower part of the intestine where most of the critical fermentation, digestion, and absorption of feed takes place. The colon is a piece of intestine that is approximately 9 feet long, 10 inches in diameter and weighing 150 lbs when it contains feed. When this giant organ is unhealthy, so is the horse.

The key to understanding colitis is understanding the delicate bacterial balance that exists in the colon. Anything that disrupts this balance, including infectious agents or antibiotics, can cause life threatening disease. Colitis is usually caused by Salmonella, Clostridial infection, and Potomac Horse Fever (protozoal infection).

My approach to acute colitis is to treat as it aggressively as possible early in the course of disease. This provides the best chance for survival and lowers the likelihood of complications, especially laminitis. This is a costly approach up front, but may save money in the long run. If we are able to identify the infectious agent, not only can the treatment be tailored to that agent but more is learned about the specifics of the disease process, which can help prevent recurrence in the future.

Usually these horses require intensive care (at a well equipped hospital) with IV fluids, antibiotics, anti-inflammatories, and plasma, along with many other medications and excellent nursing care. They will usually offer a variety of diagnostics which will be necessary for a specific diagnosis, and for effectively monitoring the patient through treatment.

In order to diagnose and treat colitis, a horse owners should recognize diarrhea in the adult horse as a sign of life threatening disease. Once horses begin losing large quantities of body fluid through the intestine, they rapidly go into shock and reach a point where saving them becomes very difficult and expensive.

my vet's role


Prognosis depends on the nature of the causative agent (certain bacterial species cause more serious disease than others), the immune status of the horse, and how soon treatment is provided. Horses that develop laminitis or are debilitated are less likely to survive.

further reading & resources

Author: Doug Thal DVM Dipl. ABVP