Enteritis in Horses: Inflammation of the Small Intestine

Quick Answer
  • See your vet immediately if your horse has colic signs, reduced manure, fever, depression, or large volumes of gastric reflux.
  • Enteritis means inflammation of the small intestine. In horses, it can cause pain, fluid loss into the gut, dehydration, and sometimes endotoxemia.
  • Some horses can be managed medically, but severe cases may need referral, repeated stomach decompression, IV fluids, and intensive monitoring.
  • Common diagnostics include physical exam, rectal exam, nasogastric intubation, bloodwork, ultrasound, and sometimes abdominal fluid testing.
  • Typical US cost range is about $350-$1,200 for an on-farm emergency workup, $1,500-$4,500 for medical hospitalization, and $5,000-$10,000+ if surgery is needed to rule out or treat a surgical colic.
Estimated cost: $350–$10,000

What Is Enteritis in Horses?

Enteritis is inflammation of the small intestine. In horses, that inflammation can interfere with normal movement of fluid and feed through the gut. The result may look a lot like colic at first, but the problem is more than pain alone. Affected horses can lose large amounts of fluid into the intestine, become dehydrated, and develop electrolyte imbalances or endotoxemia.

One important form is proximal enteritis, also called anterior enteritis or duodenitis-proximal jejunitis. This condition affects the upper part of the small intestine and is often associated with large volumes of gastric reflux when your vet passes a stomach tube. Horses may start with abdominal pain, then become quieter and more depressed as fluid builds up and the intestine becomes inflamed.

Because enteritis can resemble a surgical small-intestinal blockage, early veterinary evaluation matters. Some horses recover well with medical care, while others need hospital-level monitoring to sort out whether the problem is inflammatory, infectious, obstructive, or progressing toward shock.

Symptoms of Enteritis in Horses

  • Colic signs such as pawing, looking at the flank, lying down, or rolling
  • Depression, dullness, or reduced interest in feed
  • Fever
  • Reduced manure output or absent manure
  • Large volumes of gastric reflux found when your vet passes a nasogastric tube
  • Dehydration, tacky gums, prolonged skin tent, or increased heart rate
  • Abdominal distension or fluid-filled small intestine on exam or ultrasound
  • Signs of endotoxemia such as weakness, injected gums, or worsening shock

Call your vet right away for any horse with colic signs, especially if there is fever, worsening depression, little manure, or repeated pain after medication. Enteritis can change quickly. A horse that starts with mild discomfort may become dehydrated or develop dangerous stomach distension from reflux. If your horse is sweating, repeatedly going down, has dark or tacky gums, or seems weak, treat it as an emergency.

What Causes Enteritis in Horses?

The exact cause is not always clear. In proximal enteritis, the cause is considered poorly understood, though bacterial toxins have been suspected in some cases. Merck notes possible involvement of Clostridium difficile toxins in some horses. Other horses may develop small-intestinal inflammation secondary to infectious disease, toxin exposure, feed changes, medication effects, or another gastrointestinal problem.

Infectious causes can include bacterial disease such as Salmonella or clostridial disease, though these are more often discussed with enterocolitis and diarrhea than isolated small-intestinal inflammation. Parasites can also contribute to intestinal inflammation or obstruction in younger horses, especially where deworming plans and fecal monitoring are inconsistent.

Your vet will also think about problems that can look like enteritis, including strangulating small-intestinal lesions, impactions, ileus, peritonitis, and other causes of colic. That is why diagnosis focuses not only on confirming inflammation, but also on ruling out conditions that need surgery.

How Is Enteritis in Horses Diagnosed?

Diagnosis starts with an urgent colic exam. Your vet will assess heart rate, hydration, gum color, gut sounds, temperature, and pain level. A nasogastric tube is especially important because horses with proximal enteritis may have copious reflux, and stomach decompression can be lifesaving. Your vet may also perform a rectal exam to look for distended small intestine or other causes of obstruction.

Bloodwork often includes a CBC, chemistry panel, electrolytes, and sometimes lactate to look for inflammation, dehydration, protein loss, and systemic compromise. Abdominal ultrasound can help identify fluid-filled, thickened, or poorly motile small intestine. In some cases, your vet may recommend abdominocentesis to evaluate abdominal fluid, especially when trying to distinguish inflammatory disease from a surgical lesion.

Diagnosis is often a process of combining findings rather than relying on one single test. If the picture is unclear, or if pain, reflux, heart rate, or intestinal distension remain concerning, your vet may recommend referral to an equine hospital for repeated exams, around-the-clock decompression, IV fluids, and possible surgery if a strangulating lesion cannot be ruled out.

Treatment Options for Enteritis in Horses

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$350–$1,200
Best for: Mild to moderate cases early in the course, horses with stable vital signs, or situations where your vet is trying to determine whether immediate referral is necessary.
  • Urgent farm call or clinic exam
  • Physical exam and colic assessment
  • Nasogastric intubation to check for reflux and decompress the stomach
  • Pain control and anti-inflammatory medication as your vet recommends
  • Basic bloodwork if available
  • Short-term monitoring and referral discussion if signs persist
Expected outcome: Fair if the horse responds quickly, has limited reflux, and does not show worsening pain, dehydration, or shock.
Consider: This approach may stabilize the horse, but it offers less monitoring and fewer diagnostics than hospital care. Enteritis can worsen quickly, and some horses that seem manageable at first later need hospitalization or surgery.
Most Common

Recommended Standard Treatment

$1,500–$4,500
Best for: Most horses with confirmed or strongly suspected enteritis, especially those with significant reflux, dehydration, fever, depression, or ongoing colic signs.
  • Hospitalization or intensive ambulatory medical management
  • Repeated nasogastric decompression for reflux
  • IV polyionic fluids and electrolyte support
  • CBC, chemistry, lactate, and abdominal ultrasound
  • Rectal exams and close reassessment of pain and gut function
  • Anti-inflammatory treatment and additional medications based on your vet’s findings
  • Cryotherapy of the feet and monitoring for endotoxemia-related complications when indicated
Expected outcome: Often good with timely medical treatment when the horse improves over the first 24-72 hours and a surgical lesion is ruled out.
Consider: Requires more cost, transport, and monitoring. Some horses still fail medical treatment or need surgery if the diagnosis remains uncertain or the condition deteriorates.

Advanced / Critical Care

$5,000–$10,000
Best for: Severe cases, horses with persistent pain, large reflux volumes, worsening cardiovascular signs, uncertain diagnosis, or concern for a surgical small-intestinal lesion.
  • Equine hospital ICU-level care
  • Continuous or very frequent decompression and fluid therapy
  • Expanded bloodwork, abdominal fluid analysis, and serial ultrasound
  • Plasma or colloid support when protein loss or oncotic issues are present
  • Broad-spectrum antimicrobial therapy when your vet suspects bacterial translocation, sepsis risk, or specific infectious causes
  • Surgical exploration if strangulating obstruction cannot be ruled out or the horse fails medical management
  • 24-hour monitoring for laminitis, endotoxemia, and cardiovascular instability
Expected outcome: Variable. Some horses recover well with aggressive care, while others have a guarded prognosis if shock, intestinal compromise, or surgical disease is present.
Consider: This tier offers the most information and support, but it is resource-intensive and may still not change the outcome in the most severe cases.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Enteritis in Horses

Bring these questions to your vet appointment to get the most out of your visit.

  1. Does my horse’s exam fit enteritis, or are you more concerned about a surgical colic?
  2. How much gastric reflux was present, and what does that mean for risk and treatment?
  3. Does my horse need referral today for IV fluids, ultrasound, or around-the-clock monitoring?
  4. What bloodwork or abdominal fluid tests would help guide the next step?
  5. What complications are you most worried about right now, such as dehydration, endotoxemia, or laminitis?
  6. What signs at home would mean my horse needs to be rechecked immediately?
  7. If we start with medical treatment, what findings would make surgery more likely?
  8. What is the expected cost range for farm treatment, hospitalization, and possible surgery in my area?

How to Prevent Enteritis in Horses

Not every case can be prevented, especially when the exact cause is unclear. Still, good gastrointestinal management lowers risk. Work with your vet on a consistent feeding routine, gradual diet changes, clean water access, and a parasite-control plan based on fecal testing and targeted deworming rather than guesswork alone.

Reduce exposure to infectious disease by keeping feed and water clean, isolating horses with fever or diarrhea when advised, and practicing careful manure management. Review medication use with your vet, especially if your horse needs repeated NSAIDs, because some drugs can contribute to gastrointestinal irritation.

The most practical prevention step is early action. Horses with small-intestinal disease often do better when your vet evaluates them before dehydration, severe reflux, or endotoxemia become advanced. If your horse shows colic, fever, reduced appetite, or less manure than normal, prompt assessment can make treatment safer and more effective.

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