Common Digestive Problems in Horses and How to Spot Them Early

Last updated: June 15, 2026

By: Miles HenryFact Checked

One gelding in my barn looked perfectly healthy — good weight, eating well, no obvious signs of trouble. Then one morning he was off his feed, slightly dull, and showing just enough discomfort to worry me. By afternoon we had a vet on the way. Caught early, it resolved quickly; ignored another day, it might have been surgery. Horse digestive problems don’t always announce themselves — they build quietly until they can’t be ignored, and the difference between a manageable problem and an emergency is often just how fast you notice.

This guide covers the most common digestive problems in horses — what they are, what causes them, how to catch them early, and when to stop watching and call the vet. The anatomy behind all of it is covered in detail in our horse digestion guide; this article focuses entirely on what goes wrong and what you need to do about it.

Why Horse Gut Health Matters

The hindgut relies on billions of microbes to ferment fiber into energy, and that microbial ecosystem is sensitive to disruption. A large portion of the horse’s immune system is associated with the gastrointestinal tract — chronic digestive stress affects immunity, coat quality, energy metabolism, and behavioral stability. Problems that would barely register in other livestock species can escalate to emergencies in a horse within hours.

For horses in active work — particularly racehorses — the stakes are higher. Training stress increases gastric acid production. Transport disrupts the hindgut microbiome. Irregular feeding around race days creates gaps in forage access that leave the stomach unprotected. Managing gut health in performance horses is part of managing their performance, not separate from it.

How digestive problems affect horse health and performance — the cascade from gut to performance

Digestive issue	Primary health effect	Performance / behavioral signal
Gastric ulcers	Erosion of stomach lining; chronic pain	Girthiness, reluctance to work, weight loss despite eating, dull coat
Hindgut acidosis	Microbial collapse; pH disruption in cecum	Laminitis risk, loose manure, behavioral changes, poor recovery
Impaction colic	Obstruction in large colon; dehydration	Reduced manure output, mild pawing, loss of appetite — escalates quickly
Gas colic	Fermentation buildup; distension	Restlessness, flank-watching, kicking at belly — can resolve or rapidly worsen
Poor nutrient absorption	Malabsorption from damaged intestinal lining	Weight loss despite adequate feed, underperformance, dull coat, low energy
Chronic stress / ulcers	Elevated cortisol; reduced gut motility	Cribbing, wood-chewing, irritability, reduced willingness to train

Common Digestive Problems in Horses

These are the conditions you’re most likely to encounter in an active horse barn. They share overlapping symptoms — which is why early observation matters more than trying to self-diagnose. A veterinarian confirms the specific problem; your job is to notice something is off and act.

Common equine digestive problems — causes, signs, and veterinary urgency

Condition	Main causes	Key signs	Urgency
Gas colic	Fermentation buildup, feed changes, fast eating	Pawing, flank-watching, restlessness, mild rolling	Call vet — can resolve or escalate; don’t wait more than 30 min
Impaction colic	Dehydration, coarse dry forage, reduced gut motility	Reduced manure, decreased appetite, mild to moderate pain	Call vet — impactions worsen without treatment
Displacement / torsion	Anatomical variation, gas accumulation, unknown	Severe pain, sweating, rapid pulse, no response to pain relief	Emergency — often requires surgery
Gastric ulcers (EGUS)	Stress, fasting, high-grain diet, NSAIDs, irregular feeding	Girthiness, poor appetite, weight loss, dull coat, teeth grinding	Vet diagnosis needed — confirmed via gastroscopy
Hindgut acidosis	Starch overload, sudden feed changes, low forage	Loose manure, undigested feed in manure, laminitis risk, behavioral changes	Vet consultation — adjust management; urgent if laminitis signs appear
Diarrhea / colitis	Feed change, stress, infection, antibiotics, parasites	Watery stools, tail staining, dehydration, possible fever	Call vet if persistent over 24 hours or accompanied by fever
Choke	Bolting feed, dry pellets, poor dentition	Coughing, gagging, feed-laced nasal discharge, neck stretching, anxiety	Call vet immediately — horse cannot clear it alone

Colic is the condition most horse owners know to fear, and for good reason — it’s the leading cause of digestive-related death in horses. Gas colic is often the most benign, resolving with walking and time. Impaction is more serious and requires veterinary intervention to prevent worsening. Displacement and torsion are surgical emergencies. The problem is that early gas colic and early torsion can look identical in the first hour. That’s why the appropriate response to any colic sign is the same: call your vet and let them decide urgency. See our complete colic guide for what to do while you wait.

Gastric ulcers are the most common chronic digestive condition in performance horses. Research has found prevalence exceeding 90% in some racehorse populations — a figure that reflects how poorly twice-daily feeding matches the stomach’s design for continuous forage intake. The stomach secretes acid continuously; without forage to buffer it, that acid erodes the squamous mucosa. Mild ulcers produce subtle signs. Severe ones affect willingness to work, weight maintenance, and overall attitude. Our horse ulcer guide covers diagnosis and treatment in detail.

Hindgut acidosis develops when excess starch bypasses the small intestine and reaches the cecum, where rapid lactic fermentation drops the pH and kills beneficial microbes. The microbial collapse that follows increases laminitis risk and can cause significant behavioral changes — a horse that seemed fine one day becomes sour, foot-sore, and loose the next. This is the condition behind most of the catastrophic outcomes from grain overload. For the full anatomy of how this happens, the horse digestion guide covers it in detail.

Choke is an esophageal obstruction — feed lodged before it reaches the stomach. Because horses cannot vomit, they cannot clear the obstruction themselves. Signs are unmistakable: coughing, gagging, and feed-laced discharge from the nostrils. Some cases resolve with time and hydration; others require veterinary intervention to prevent aspiration pneumonia. Remove all feed and water, keep the horse calm, and call your vet.

Diarrhea and Colitis in Horses

Diarrhea in horses ranges from a loose stool that resolves in a day to severe colitis that requires intensive veterinary care. The most common causes are sudden feed changes, stress, antibiotic disruption of the hindgut microbiome, viral or bacterial infection, and parasites. In most cases, a single episode of mild loose stool with no other symptoms warrants monitoring rather than an emergency call. Persistent diarrhea — particularly when paired with fever, lethargy, or signs of dehydration — is a different situation entirely.

Colitis is an inflammation of the large colon that can develop from salmonella, clostridial infection, or severe hindgut dysbiosis following antibiotic treatment. It produces profuse, watery diarrhea that depletes fluids and electrolytes rapidly. Horses with colitis can deteriorate quickly — dehydration and electrolyte imbalance become the primary threats. Any horse with watery or bloody diarrhea, fever above 102°F, or rapid deterioration needs veterinary attention the same day. Do not attempt to manage colitis at home. While you wait for the vet, ensure water is accessible and isolate the horse from others if infectious disease is possible.

After diarrhea resolves — especially following antibiotic treatment — restoring hindgut microbial balance through gradual reintroduction of quality forage is more consistently effective than probiotics alone, though equine-specific probiotics may provide additional support in some cases.

What Causes Digestive Problems in Horses?

Most digestive problems in horses trace back to management decisions, not bad luck. Understanding which factors consistently cause trouble makes prevention straightforward — even if execution requires discipline.

Sudden diet changes are probably the most common single cause of acute digestive upset. The hindgut’s microbial population adapts slowly — it needs 7–14 days to adjust to a new hay type, grain blend, or pasture. Change it abruptly and the microbes that were thriving on the old diet struggle with the new one, producing fermentation imbalances that cause gas, loose manure, or colic. This applies to hay source changes between cuttings, switching grain brands, and introducing spring pasture.

High-starch, low-forage diets overload the small intestine’s absorption capacity and push undigested starch into the hindgut, where it ferments acidically. The resulting drop in pH kills beneficial bacteria, increases laminitis risk, and contributes to hindgut acidosis. The solution isn’t eliminating grain — it’s limiting grain per meal and keeping forage as the dietary foundation.

Stress from travel, competition, and herd changes disrupts gut motility and increases gastric acid production. Horses that compete regularly, haul frequently, or experience frequent herd changes are at elevated ulcer risk. The stress doesn’t have to be dramatic — even the routine stress of a busy race barn accumulates over a season.

Parasites — particularly strongyles — damage the intestinal lining and interfere with nutrient absorption. Heavy parasite burdens cause chronic digestive inflammation that’s often mistaken for other problems. A targeted deworming program based on fecal egg counts, rather than calendar-based rotation, is more effective at protecting gut health without contributing to resistance. Our parasite guide covers the current recommended approach.

Dental problems are a silent contributor. Improper chewing from sharp points, uneven wear, or tooth pain sends larger feed particles into the stomach and hindgut, where they ferment improperly or cause impactions. Annual dental exams are worth the cost — they protect the first step in the entire digestive process.

Dehydration concentrates digesta in the large colon and makes it difficult to move through. The pelvic flexure — a sharp bend in the large colon — is the most common impaction site, and dehydration is its most common precursor. In Louisiana heat, water intake in horses drops significantly when water temperatures rise; cold or room-temperature water in summer, heated buckets in winter, and free-choice salt year-round all help maintain intake.

Moldy or contaminated feed produces mycotoxins that reduce appetite, disrupt fermentation, and increase colic risk. Small amounts of mold can be dangerous. Horses rarely refuse moldy hay if they’re hungry enough — which means the owner has to catch it before it goes in the rack. Store hay elevated in a well-ventilated area, and check each bale before feeding.

Long gaps between meals leave the stomach producing acid with nothing to buffer it. Horses were designed to trickle-feed for 16–18 hours per day. A barn that feeds twice daily at 6 AM and 5 PM leaves an 11-hour overnight gap with no forage — in a stomach that secretes acid around the clock. The simplest fix is making sure hay is available between meals rather than waiting for the next feeding.

Early Warning Signs to Watch For

Digestive problems often show up behaviorally before they become clinical. The horse that’s slightly off, slightly resistant, slightly less interested in feed — these are the signals that matter. By the time a horse is rolling in the stall, the problem has usually been building for hours or days.

Manure is the most consistent daily diagnostic tool available. A healthy horse in active training produces 8–12 manure piles per day with well-formed fecal balls and visible fiber content. Deviations from that baseline — in volume, consistency, or frequency — are among the earliest reliable signals of a developing problem. The cost of paying attention to manure is zero; the cost of missing what it’s telling you can be considerable.

Daily Prevention Practices

Prevention is not complicated, but it requires consistency. The horse that gets managed the same way every day — same feeding times, same forage access, same monitoring routine — is the horse that rarely develops digestive problems. The horse that’s managed inconsistently, even with good intentions, is the one that ends up with a vet call.

Daily digestive health practices — what to do, why it matters, and how often

Area	Practice	Why it matters	Frequency
Forage access	Keep hay available between meals; never let the hay rack go empty overnight	Continuous forage buffers stomach acid and feeds the hindgut microbiome	Daily — non-negotiable
Feeding schedule	Feed at consistent times; minimize gaps between meals over 4 hours	Irregular schedules create acid exposure periods and stress hormones that increase ulcer risk	Daily
Feed transitions	Change hay type, grain brand, or pasture access over 7–14 days minimum	Hindgut microbes need time to adapt; abrupt changes trigger fermentation imbalances	Whenever changing feed
Grain limits	Keep each grain meal under 4–5 lbs for an average-sized horse	Larger meals overflow the small intestine and send starch into the hindgut	Every meal
Water access	Fresh, clean water available at all times; monitor intake in heat and cold	Dehydration is the leading cause of impaction colic	Daily
Manure monitoring	Count and assess manure piles daily; note changes in consistency or volume	Manure is the earliest and most reliable diagnostic signal for developing problems	Daily
Dental care	Annual dental exam; float teeth as needed	Poor dentition creates large feed particles that ferment improperly or cause impactions	Annually minimum
Deworming	Targeted deworming based on fecal egg counts, not calendar rotation	Parasite damage to intestinal lining disrupts nutrient absorption and causes chronic inflammation	Per vet recommendation
Stress reduction	Consistent turnout, familiar herd mates, low-disruption routines	Stress elevates cortisol, reduces gut motility, and increases acid production	Daily management
Feed storage	Store hay elevated and ventilated; inspect each bale before feeding	Mold produces mycotoxins that disrupt fermentation and reduce appetite	Ongoing

For racehorses specifically, race-day and travel management deserve extra attention. The combination of transport stress, irregular feeding around race time, and Lasix-induced dehydration creates a perfect environment for ulcer development and electrolyte imbalance. Maintaining forage access as close to race time as practical, and prioritizing rehydration and a calm post-race routine, protects gut health during the highest-stress periods. Our racehorse nutrition guide covers the race-day feeding protocol in detail.

When to Call Your Vet Immediately

Early signs warrant observation and monitoring. These signs warrant a phone call right now — don’t wait to see if they improve.

Digestive emergencies — symptoms requiring immediate veterinary contact

Symptom	What it may indicate	What to do
Violent rolling, thrashing, sweating	Severe colic — displacement, torsion, or severe impaction	Call vet immediately. Remove feed. Walk gently only if directed. No medication without vet instruction
No manure passed for 12+ hours	Impaction — dehydration-related obstruction	Call vet promptly. Impactions worsen quickly without treatment
Coughing, gagging, feed from nostrils	Choke — esophageal obstruction	Remove feed and water. Keep horse calm. Call vet. Do not attempt to clear it
Reluctance to move, warm hooves, shifting weight	Early laminitis secondary to hindgut acidosis	Call vet urgently. Remove grain. Limit movement unless directed otherwise
Distended abdomen, failure to respond to initial colic treatment	Possible displacement or torsion — surgical risk	Emergency. Call vet immediately. Be prepared for transport to a surgical facility
Persistent diarrhea with fever or lethargy	Colitis, severe hindgut infection, or systemic illness	Call vet same day. Monitor hydration. Do not attempt to manage without diagnosis

Frequently Asked Questions