A horse with colitis needs food that is easy to digest and gentle on an inflamed colon. The specific approach depends on whether your horse has acute colitis (sudden onset, often with diarrhea) or right dorsal colitis (typically caused by overuse of anti-inflammatory drugs), but the core principle is the same: reduce the workload on the large intestine while keeping calories and protein coming in.
Keep the Horse Eating
One of the biggest mistakes during a colitis episode is pulling all feed. Horses with colitis often still have some appetite, and they should be encouraged to eat. Good-quality hay, fresh green grass, and highly digestible concentrate feeds with 12% to 14% protein are the standard recommendations for horses with acute colitis who are willing to eat. The goal is to maintain body condition and provide the nutrients the gut lining needs to repair itself, while avoiding anything that could worsen inflammation.
Small, frequent meals are better than two large ones. Smaller portions reduce the volume of material hitting the colon at any given time, which matters when the tissue is swollen and struggling to absorb water normally.
Right Dorsal Colitis Requires a Different Approach
If your horse has right dorsal colitis, the feeding strategy changes significantly. This form of colitis develops when non-steroidal anti-inflammatory drugs damage the lining of a specific section of the colon. The damaged tissue can’t handle the physical bulk of normal forage, so long-stemmed hay needs to be restricted or eliminated entirely for at least three months.
In place of hay, horses with right dorsal colitis are fed a forage-based complete pelleted feed. These pellets contain the fiber the horse needs but in a form that’s already broken down, so the colon doesn’t have to do the heavy mechanical work of processing long stems. This allows the mucosal lining to heal without constant irritation. It’s a significant dietary shift, and the timeline is not short. Three months is the minimum, and some horses need longer before they can tolerate hay again.
Fiber Over Starch
Regardless of the type of colitis, the diet should prioritize fiber and minimize starch. Research comparing high-fiber and high-starch diets in horses found that starch-heavy feeding caused more severe inflammation in the jejunum and the pelvic flexure of the colon, along with worse stomach lesions. For a horse whose colon is already inflamed, adding starch is like pouring fuel on a fire.
For horses that need a low-sugar diet, forages with less than 10% nonstructural carbohydrates (the combined total of sugars, fructans, and starch) are the general target. You can get this number from a forage analysis, which any hay supplier or agricultural extension office can help with. Sweet feeds, grain-heavy concentrates, and treats high in sugar or molasses should be off the table entirely during recovery.
Beet pulp (without added molasses) is a useful fiber source for colitis horses because it’s highly digestible and low in starch. It also absorbs a significant amount of water, which can help with hydration in a horse losing fluid through diarrhea.
Omega-3 Fatty Acids Can Help With Inflammation
Supplementing with omega-3 fatty acids, specifically the types found in marine-derived fish oil (EPA and DHA), may reduce inflammation in the colon. These fatty acids work by dialing down the production of inflammatory signaling molecules in the gut.
The source matters here. Vegetable oils like corn oil or soybean oil are not effective substitutes. They contain a different type of fatty acid that doesn’t have the same anti-inflammatory effect. You need a marine-derived omega-3 supplement designed for horses to get the EPA and DHA that actually make a difference.
What About Probiotics?
Probiotics are a common suggestion for horses with gut problems, but the evidence is limited. One controlled study tested Saccharomyces boulardii (a probiotic yeast) in horses with antibiotic-associated diarrhea, giving 25 grams orally every 12 hours. The yeast did survive in the gut of about 58% of treated horses by day three, confirming it can stay alive in a sick horse’s digestive system. However, the study found no significant differences between treated and untreated horses in how quickly diarrhea resolved, how fast vital signs normalized, or survival rates. Probiotics won’t hurt, but they shouldn’t be relied on as a primary treatment.
Hydration Is as Important as Feed
Colitis causes significant fluid loss through diarrhea, and dehydration can become dangerous quickly. Fresh, clean water should always be available. Adding a small amount of loose salt to feed or offering a salt block can encourage drinking. Some owners add water to pelleted feeds or beet pulp to create a soupy mash, which is an easy way to sneak in extra fluid with every meal. Electrolyte supplements designed for horses can help replace sodium, potassium, and chloride lost through watery stool, but severe cases typically need veterinary-administered fluid support that goes beyond what oral supplementation can provide.
Reintroducing Hay After Recovery
The transition back to a normal diet should be gradual, especially for horses recovering from right dorsal colitis. After at least three months on a pelleted diet (and with veterinary confirmation that healing is progressing), long-stemmed forage can be reintroduced slowly. Start with small amounts of soft, high-quality grass hay and monitor for any return of symptoms like loose stool, discomfort, or weight loss.
Grain or concentrate feeds should be the last thing added back, and only after the horse is tolerating forage well and gastrointestinal function looks normal. Rushing this process risks re-irritating tissue that hasn’t fully healed. For horses recovering from acute colitis, the timeline is generally shorter, but the same principle applies: hay first, grain later, and only when the gut is clearly moving material through at a normal rate.
Foods to Avoid During Colitis
- High-starch grains like corn, barley, and oats in large quantities. These ferment rapidly in the hindgut and can worsen inflammation.
- Sugary treats and molasses-coated feeds. Excess sugar feeds the wrong microbial populations in a disrupted gut.
- Long-stemmed hay if the horse has right dorsal colitis. The physical bulk irritates the damaged colon wall.
- Lush, fructan-rich pasture. Spring and fall grass can be especially high in nonstructural carbohydrates, which are problematic for an inflamed colon.
- Vegetable oils as a substitute for marine-derived omega-3s. Corn and soybean oil don’t provide the specific fatty acids that help reduce gut inflammation.
Any horse with colitis should have its diet managed in close coordination with a veterinarian, particularly when deciding how long to restrict roughage and when to begin reintroduction. Ultrasound imaging of the colon wall can help track healing and guide those decisions with more precision than symptoms alone.