The single most effective dietary change for a horse with loose droppings is increasing the amount of long-stem, mature hay in the diet. Fiber is what drives healthy fermentation in the hindgut, and when fiber intake drops or gets replaced by too much grain, lush pasture, or rich feeds, stool consistency suffers. Before adjusting the diet, though, it helps to understand what’s actually going on, because not all loose droppings have the same cause or the same fix.
Loose Droppings vs. Free Fecal Water
There are two distinct problems that owners often lump together. True loose droppings (diarrhea) means the entire stool is soft, cow-patty-like, or watery. Free fecal water syndrome is different: the manure balls themselves look normal, but thin, brownish water runs out before, during, or after the horse defecates. The feeding strategies overlap, but the causes can differ significantly.
Loose stools typically point to a digestive issue: hindgut imbalance, too much sugar or starch, parasites, infection, or sudden feed changes. Free fecal water syndrome is less well understood. A large study in Germany found it was more common in horses with low social rank in a group, especially during winter when confined spaces increase stress. Dental disease, parasites, and cold water intake were not linked to the condition in that research. If your horse has free fecal water rather than genuinely soft manure, social stress and management changes may matter as much as diet.
Make Hay the Foundation
A horse’s digestive system is built to process large volumes of fibrous forage over many hours. The current recommendation is a minimum of 1.5% of body weight per day in forage dry matter. For a 500 kg (1,100 lb) horse, that works out to about 7.5 kg of dry matter, or roughly 8.3 kg (18 lbs) of hay on an as-fed basis. Some nutritionists consider even that a floor, not a target, noting that amounts below 12.5 grams per kilogram of body weight fail to meet basic behavioral and health needs. In practical terms, most horses with loose droppings benefit from free-choice or near-free-choice hay access.
The type of hay matters. Timothy, orchard grass, and Bermuda grass hays are moderate in sugar and protein, making them good default choices for a sensitive gut. Alfalfa is higher in protein and calories, and some horses develop softer stools on it. If you’re currently feeding alfalfa, try switching to a grass hay or blending the two. Going without forage for more than four to five consecutive hours can itself disrupt hindgut function, so splitting hay into multiple feedings or using slow-feed nets helps keep the gut working steadily.
Limit Lush Pasture
Young, fast-growing pasture is high in water and low in structural fiber, a combination that commonly softens manure. Horses turned out on lush spring or fall grass often develop loose droppings simply because they’re consuming far more moisture and sugar than their hindgut can handle efficiently. If your horse grazes rich pasture and has soft stools, offer free-choice hay alongside turnout. Many horses will self-select the hay they need to balance their fiber intake. You can also limit grazing hours or use a grazing muzzle during peak growth periods.
Cut Back on Grain, Sugar, and Starch
When starch and sugar from grain or sweet feeds reach the hindgut undigested, they ferment rapidly, producing lactic acid. This drops the pH in the cecum and colon, kills off beneficial fiber-digesting bacteria, and draws water into the gut. The result is loose, acidic manure, sometimes with a sour smell. This process, called hindgut acidosis, is one of the most common dietary causes of persistent soft stools in horses that receive concentrates.
If your horse is getting grain or a pelleted concentrate, reduce the amount gradually and see if the droppings firm up. When concentrates are necessary for energy or nutrition, choose feeds labeled as low in non-structural carbohydrates (NSC), and split meals into smaller portions so less starch hits the hindgut at once. For many horses with loose droppings, replacing grain calories with a high-fat, high-fiber feed (like beet pulp or a stabilized rice bran product) resolves the issue.
Yeast Supplements for Hindgut Support
Live yeast supplements based on Saccharomyces cerevisiae (brewer’s yeast) have a growing body of evidence behind them for horses with digestive instability. In controlled studies, daily yeast supplementation increased fiber digestibility, boosted populations of beneficial fiber-digesting bacteria, and reduced lactic acid levels in the cecum and colon. It also increased populations of bacteria that consume lactate, helping stabilize hindgut pH.
These effects were seen across a range of dosages, from modest daily amounts to higher therapeutic doses. Commercial equine yeast supplements are widely available in pellet or powder form. Look for products that list a guaranteed live cell count on the label. Results typically take a few weeks to become apparent as the microbial population shifts.
Psyllium for Sand-Related Issues
Horses that eat off sandy ground or graze short, sandy pastures can accumulate sand in the colon, which irritates the gut lining and causes loose, gritty droppings. You can check for sand by placing a few manure balls in a rubber glove filled with water, mixing thoroughly, and letting it settle. Sand will collect in the fingertips.
If sand is the culprit, psyllium husk is the standard treatment. The dose used in veterinary research is 1 gram per kilogram of body weight once daily for a minimum of 10 days. For a 500 kg horse, that’s about 500 grams (roughly one pound) per day, mixed into a damp feed. Some manufacturers recommend lower doses, but the research supporting effective sand clearance used the 0.5 to 1 g/kg range. After the initial course, many owners feed psyllium one week per month as prevention.
Keep Electrolytes and Water Available
Loose droppings increase water and mineral loss. Fecal water output can more than double during bouts of diarrhea, and sodium losses through manure rise sharply. A plain white salt block should always be available, but horses with persistent loose stools may benefit from 1 to 2 tablespoons of loose table salt added directly to feed daily, since many horses don’t lick blocks aggressively enough to replace what they’re losing. Potassium losses also climb, though most forage-based diets supply adequate potassium on their own.
Monitor hydration by pinching a fold of skin on the horse’s shoulder into a tent shape and releasing it. In a well-hydrated horse, the skin snaps flat immediately. If it stays raised for two or more seconds, the horse is mildly dehydrated. Skin that stays tented for four to five seconds or longer signals serious fluid loss. You can also press a thumb against the upper gum: the pale spot should refill with color within one to two seconds. Anything slower suggests significant dehydration or circulatory compromise.
Make Feed Changes Gradually
The microbial population in a horse’s hindgut is specialized to whatever the horse has been eating. Abrupt changes, even beneficial ones, can temporarily worsen loose droppings because the microbes haven’t had time to adapt. Transition any new hay, feed, or supplement over 7 to 14 days, mixing increasing proportions of the new feed with the old. This is especially important when switching hay types or moving from pasture to hay.
When Loose Droppings Signal Something Bigger
Most cases of soft manure respond to the dietary adjustments above within a week or two. But loose droppings that are profuse and watery, contain blood or mucus, come with fever above 101.5°F, or are paired with a resting heart rate above 44 beats per minute deserve prompt veterinary attention. The same goes for droppings that don’t improve despite diet changes, since chronic diarrhea can indicate conditions like inflammatory bowel disease, liver dysfunction, or a heavy parasite burden that diet alone won’t fix. A fecal egg count is a cheap, easy first step to rule out worms as a contributing factor.