Bit & Bridle

Equine Gastric Dilatation and Volvulus (GDV)

Other Names

  • Gastric rupture
  • Stomach torsion
  • Gastric bloat
  • Acute gastric dilation

What is Gastric Dilatation and Volvulus (GDV) in Horses?

Gastric dilatation and volvulus (GDV) — also referred to in equine medicine as acute gastric dilatation or, in severe cases, gastric rupture — is a rare but rapidly life-threatening emergency in horses. Unlike dogs, in which GDV is a common and well-characterised condition, true gastric volvulus (rotation of the stomach on its axis) is exceptionally rare in horses due to the anatomy of the equine gastrointestinal tract. However, primary gastric dilatation — extreme distension of the stomach with gas, fluid, or ingesta — is a recognised and urgent equine condition that shares some features.

The equine stomach is a relatively small organ (capacity of approximately 8–15 litres in an adult horse) compared to the total volume of the gastrointestinal tract. Horses cannot vomit effectively, which means any obstruction to gastric outflow or excessive gas accumulation can lead to rapidly increasing pressure within the stomach. If left untreated, this can progress to gastric rupture — a catastrophic event that is almost universally fatal.

Secondary gastric dilatation is far more common than primary dilatation in horses and occurs as a consequence of small intestinal obstruction, impaction colic, or ileus (failure of intestinal motility) — all of which prevent normal gastric emptying.

Causes

Gastric dilatation in horses can arise from several causes:

  • Obstructive causes: Duodenal impaction, proximal jejunal obstruction, or strangulating lesions of the small intestine can prevent gastric contents from passing forward into the intestine, resulting in reflux accumulation and gastric distension.
  • Excessive fermentable carbohydrate ingestion: Consuming large amounts of rapidly fermentable feed (lush spring grass, grain overload) can lead to excessive gas production in the stomach, causing acute dilatation. This is a particular risk in horses that gain access to feed rooms or lush pasture without gradual introduction.
  • Ileus: Post-surgical ileus or paralytic ileus (loss of intestinal motility) following colic surgery or systemic illness can lead to accumulation of fluid and gas in the stomach.
  • Grass sickness (equine dysautonomia): This serious neurological condition, caused by Clostridium botulinum-related toxins, causes profound ileus and frequently leads to severe gastric reflux accumulation.
  • Sand impaction: In some cases, sand accumulation in the stomach or duodenum can impair gastric outflow.

Symptoms and Signs

  • Severe abdominal pain (colic): The horse shows signs of extreme discomfort — pawing, looking at the flank, rolling, inability to stand still, throwing itself to the ground.
  • Distended abdomen: The left flank in particular may appear visibly bloated in severe cases.
  • Elevated heart rate: Tachycardia is a consistent finding; heart rates above 60 beats per minute indicate significant pain and cardiovascular compromise.
  • Nasogastric reflux: When a stomach tube is passed by a veterinarian, large volumes of foul-smelling fluid reflux back — sometimes 10–20 litres or more. This is both diagnostic and immediately therapeutic.
  • Sweating and anxiety: Profuse sweating, dilated nostrils, and a visibly distressed demeanour.
  • Signs of shock: Pale or congested mucous membranes, prolonged capillary refill time, cold extremities, and weak pulse in severe or late-stage cases.
  • Sudden deterioration or death: Gastric rupture typically causes sudden, dramatic deterioration — the horse may appear to calm momentarily as the pressure is released, then rapidly deteriorate into irreversible shock.

Diagnosis

  • Nasogastric intubation: Passing a stomach tube through the nostril into the stomach is both diagnostic and therapeutic. Recovery of large volumes of reflux (>2 litres) confirms gastric dilatation and provides immediate relief. This is one of the most important early interventions in any colic case.
  • Rectal examination: Allows assessment of other gastrointestinal structures and identification of concurrent intestinal pathology causing secondary gastric dilatation.
  • Abdominal ultrasonography: Can identify distended small intestine, assess gut motility, and identify free abdominal fluid (which may indicate rupture).
  • Peritoneal fluid analysis (abdominocentesis): Sampling abdominal fluid can assess for signs of intestinal compromise or rupture. Abnormal fluid with high protein and white cell count indicates serious pathology.
  • Blood tests: Haematology and biochemistry assess the degree of dehydration, electrolyte imbalances, and metabolic compromise, and help guide treatment.

Treatment

Gastric dilatation is a veterinary emergency requiring immediate intervention:

  • Nasogastric decompression: Passing a stomach tube and allowing or facilitating drainage of gastric contents is the single most important initial treatment. This relieves pressure, reduces pain, and prevents progression to rupture.
  • Intravenous fluids: Rehydration and electrolyte correction are essential, particularly in horses that have been colicking for several hours.
  • Pain management: Analgesics including flunixin meglumine and butorphanol are used to manage pain. Sedation with detomidine or xylazine may be required for horses in severe pain.
  • Treating the underlying cause: If gastric dilatation is secondary to intestinal obstruction or strangulation, surgical colic (exploratory laparotomy) is frequently necessary to resolve the primary problem and prevent recurrence. This is a major surgical procedure performed at equine referral hospitals.
  • Repeated nasogastric intubation: In horses with ongoing reflux, the stomach tube may need to be passed repeatedly (every 2–4 hours) or left in place to allow continuous drainage.
  • Prokinetics: Drugs that stimulate gut motility (such as neostigmine, metoclopramide, or lidocaine infusions) may be used in cases of ileus.

Suspected gastric rupture requires emergency veterinary assessment. If rupture is confirmed, humane euthanasia is almost always the only option, as the prognosis is universally fatal without immediate intervention that is rarely feasible or successful.

Prevention

  • Feed horses in small, frequent meals rather than one or two large ones — this reflects natural grazing behaviour and reduces the risk of gastric overload.
  • Introduce new feeds, lush pasture, and dietary changes gradually over a minimum of 7–14 days.
  • Ensure horses cannot access feed stores, grain bins, or concentrated feed unsupervised.
  • Monitor grazing on lush spring pasture carefully — restrict grazing hours on rich grass, particularly in horses with a history of digestive sensitivity.
  • Maintain regular dental care to ensure adequate chewing and digestion of feed.
  • Provide constant access to fresh, clean water — dehydration contributes to impaction and reduced gut motility.
  • Ensure regular veterinary checks, particularly for horses with a history of colic, and seek prompt attention for any horse showing signs of abdominal pain.

Prognosis

Prognosis depends entirely on the underlying cause and whether gastric rupture has occurred. Horses with uncomplicated primary gastric dilatation that is treated promptly with nasogastric decompression generally recover well. Horses with secondary gastric dilatation caused by surgical lesions (strangulating obstruction, volvulus) have a prognosis that depends on the severity and duration of intestinal compromise — these cases require emergency surgery and carry variable prognoses depending on how much intestine is affected. Gastric rupture is almost universally fatal.

When to Call the Vet

Any horse showing signs of abdominal pain — however mild — requires veterinary attention without delay. Do not wait to see if it resolves. Gastric dilatation can progress to rupture very rapidly, and early nasogastric decompression can be life-saving. Never administer oral fluids, feed, or bute to a colicking horse before your vet has passed a stomach tube — in a horse with gastric dilatation, this can dramatically worsen the situation. For related conditions, see our guides on Equine Colic and equine gastrointestinal health. The British Equine Veterinary Association provides guidance on finding qualified equine vets for emergency care.

Frequently Asked Questions

Why can’t horses vomit?

Horses have a very powerful cardiac sphincter (the muscular valve between the oesophagus and stomach) that essentially only allows material to pass in one direction — into the stomach. Combined with the relatively small stomach capacity and the position of the stomach relative to the abdominal cavity, this anatomy makes vomiting extremely difficult. This is why gastric distension in horses is so dangerous — there is no safety valve, and pressure can only be relieved by passage forward into the intestine or via a nasogastric tube placed by a veterinarian.

How quickly can a horse die from gastric dilatation?

The timeline varies depending on the cause and rate of accumulation. In severe cases — particularly following grain overload — gastric pressure can reach dangerous levels within hours. Gastric rupture can occur at any point once the stomach reaches capacity. This is why any horse showing signs of colic, particularly if the abdomen appears bloated or the horse is in severe unrelenting pain, should receive emergency veterinary attention without delay — ideally within the first 1–2 hours of symptoms appearing.

Is gastric dilatation the same as colic?

Gastric dilatation is one of many causes of colic — which is simply a term for abdominal pain in horses. Not all colic is gastric dilatation, and not all gastric dilatation presents in the same way. Colic is a symptom, not a diagnosis. Only a veterinarian passing a stomach tube and performing a thorough examination can determine whether gastric dilatation is present.

What is the difference between primary and secondary gastric dilatation?

Primary gastric dilatation arises from problems originating in the stomach itself — such as excessive fermentable feed intake or pyloric (stomach outlet) obstruction. Secondary gastric dilatation occurs when intestinal disease downstream of the stomach (small intestinal obstruction, ileus) prevents gastric emptying, causing fluid and gas to accumulate. Secondary dilatation is far more common and often indicates the need for surgical intervention to address the underlying intestinal problem.