section name header

Basics ⬇

Outline

BASICS

Definition!!navigator!!

Distention of the stomach due to accumulation of dehydrated ingesta that does not clear after an appropriate fasting period.

Pathophysiology!!navigator!!

  • Can be primary or secondary; however, this definition is not used consistently.
  • Primary gastric impactions can result from disturbance of the motility of the GI tract. These can include abnormal motility patterns, abnormal gastric secretion, or functional outflow obstructions. Thickening of the muscular layers without obvious cause has been reported.
  • Secondary gastric impactions can be due to ingestion of expandable feeds, persimmon seeds, dental disease, mechanical outflow obstruction, inadequate water intake, or reduced GI motility due to systemic disease. Persimmon seed has a water-soluble tannin that polymerizes in the presence of gastric acid to form an adhesive coagulum. The coagulum reacts with cellulose and hemicellulose to form a hard solid mass. Hepatic disease, particularly caused by ragwort poisoning, has also been described as a cause of gastric impaction.
  • Dehydrated gastric impaction can be an incidental finding during surgery for intestinal obstruction.
  • Chronic impaction can result in thickening and severe dilation of the stomach wall. Up to 60 kg of ingesta has been removed from gastric impactions during surgery or at necropsy

Systems Affected!!navigator!!

  • GI—the main signs are acute or chronic colic, anorexia, weight loss, and abnormal fecal output
  • Cardiovascular—dehydration can be present

Genetics!!navigator!!

No genetic predisposition.

Incidence/Prevalence!!navigator!!

There is no prevalence data but the condition is rare. Engorgement with ripe persimmon fruit is more likely in the fall.

Geographic Distribution!!navigator!!

Worldwide

Signalment!!navigator!!

There is no reported breed, age, or sex predilection. Foals may also be affected.

Signs!!navigator!!

Historical Findings

Anorexia is the predominant reported clinical sign, often accompanied by weight loss and signs of colic. The duration of clinical signs at presentation can range from days to months. Colic signs can be acute or chronic, constant or intermittent, and can range from mild to severe. Fecal output is sometimes reduced and can be abnormal in consistency.

Physical Examination Findings

  • Horses can be lethargic and show varying degrees of anorexia and colic.
  • In acute cases tachycardia and tachypnea can be present; however, in chronic cases this is usually not seen.
  • Abdominal wall tension may be increased and GI sounds decreased. Affected horses often have a decreased body condition score.
  • Cardiovascular parameters are usually normal. Signs of dehydration can be present. Rarely, in acute cases horses have GI reflux, which can be visible at the nares or is diagnosed upon nasogastric intubation

Causes!!navigator!!

  • Primary impaction of unknown origin
  • Secondary to
    • Gastric masses (neoplasia, polyp)
    • Pyloric masses (neoplasia, polyp)
    • Pyloric thickening (chronic ulcer disease)
    • Obstruction due to expandable feeds (wheat, barley, and sugar beet pulp)
    • Phytobezoar (persimmon seeds, mesquite beans)
    • Any systemic disease affecting GI motility
    • Hepatic disease
  • In some cases an obvious cause cannot be found

Risk Factors!!navigator!!

  • Ingestion of certain feeds that swell or form a mass after ingestion
  • Dental disease resulting in improper chewing of the food
  • Inadequate water supply
  • Rapid eating

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

Delayed gastric emptying due to systemic disease.

CBC/Biochemistry/Urinalysis!!navigator!!

Abnormalities are inconsistent and depend on the duration of the disease as well as the underlying cause.

Other Laboratory Tests!!navigator!!

None

Imaging!!navigator!!

Abdominal US

Should be performed to evaluate the stomach. The normal equine stomach usually extends over 5 ICSs (10th–15th ICS) and is visible dorsal to the spleen and ventral to the lung on the left side. In horses with gastric distention the stomach is displaced dorsocaudally, extends >5 ICSs and can be visible from both sides, sometimes up to the paralumbar fossa. Care has to be taken not to overinterpret findings from US. Repeated US should be performed to assess whether findings are consistent. Gastric wall thickness of >10–35 mm has been reported (normal 1–5 mm).

Abdominal Radiographs

Often inconclusive and are mainly used to rule out differential diagnosis for recurrent colic.

Other Diagnostic Procedures!!navigator!!

Rectal Examination

The spleen is often displaced medially and caudally in the abdomen. In chronic cases with severe gastric dilation the enlarged stomach can be felt on rectal examination.

Nasogastric Intubation

Should be performed to rule out or relieve gastric distention. While reflux is not a feature in chronic cases, it can occur in acute cases. Difficulties passing the nasogastric tube beyond the cardia have been reported.

Gastroscopy

Visualization of the stomach, in particular of the margo plicatus, is precluded owing to dehydrated feed material. The horse should have been fasted for a minimum of 16 h to diagnose this condition. In the case of persimmon fruit phytobezoars the seeds can often be seen on the surface of the gastric impaction

Laparoscopy or Exploratory Laparotomy

The only definitive method to diagnose a gastric impaction is exploratory celiotomy.

Liver Biopsy

Should be performed when clinical or laboratory findings suggest an underlying hepatic cause.

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

Horses can be managed on the farm. As diagnosis often requires specialized equipment referral to a hospital may be indicated. Medical and surgical treatment has been described.

Nursing Care!!navigator!!

  • IV fluid therapy using an electrolyte solution (e.g. lactated Ringer's solution) should be instituted if dehydration is present and to attempt to soften the gastric contents. The rate of fluid administration depends on the degree of dehydration and should exceed maintenance requirements (2–4 mL/kg/h). Once the gastric impaction resolves, IV fluid therapy should be discontinued. If no improvement or resolution within 3–5 days, IV fluid therapy should be discontinued; it likely will not have further benefits.
  • Enteral fluid therapy should be instituted to attempt to resolve the gastric impaction. Care should be taken to avoid rupture of the stomach. Note that rupture can occur even if fluid therapy is done correctly. The amount of fluid administered depends on the fill and size of the stomach (2–6 L every 2–4 h over 1.5 days).
  • Gastric lavage can be attempted using water alone or with mineral oil or magnesium sulfate. The use of carbonated cola has also been reported to be successful to resolve gastric impactions. In most cases gastric lavage has to be performed repeatedly. Gastric rupture can occur during gastric lavage. Gastric lavage should therefore be started conservatively using small amounts (1–2 L of fluid at a time). If this is tolerated well, the amount of fluid used can be increased gradually

Diet!!navigator!!

  • Fasting is indicated until a diagnosis is reached and during resolution of the gastric impaction. Once the impaction is resolved, feeding should be reinstituted gradually.
  • Animals that are held off feed for prolonged periods of time and present in poor body condition may benefit from parenteral nutrition

Client Education!!navigator!!

Clients should be made aware of:

  • The guarded prognosis in cases where the impaction cannot be resolved or the stomach shows signs of thickening and enlargement
  • The risk of gastric rupture, which could occur spontaneously or during treatment with gastric lavage or enteral fluid therapy

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • The use of laxatives is suggested in the literature; however, there is no conclusive evidence for the effectiveness. Mineral oil (1–5 L every 4–6 h per nasogastric tube for 1–5 days) or magnesium sulfate (1 g/kg every 12–24 h per nasogastric tube for 1–5 days) can be used. Carbonated cola has been reported to resolve gastric impactions in humans and horses, although its effect is questionable.
  • Flunixin meglumine (1.1 mg/kg every 12 h IV) if needed to control signs of colic.
  • Prokinetic drugs such as bethanechol (0.2–0.4 mg/kg PO every 6–8 h or 0.03–0.04 mg/kg SC or IV every 6–8 h) or metoclopramide (0.6 mg/kg PO every 4–6 h or 0.04 mg/kg/h CRI) can be used in an attempt to facilitate gastric emptying. They are unlikely to show effect without lavaging the stomach and breaking up the impaction

Contraindications!!navigator!!

None

Precautions!!navigator!!

Caution should be used when treating horses with preexisting renal disease with NSAIDs.

Possible Interactions!!navigator!!

None

Alternative Drugs!!navigator!!

  • Other NSAIDs can be used as analgesics. An alternative to NSAIDs for analgesia is butorphanol (0.01–0.1 mg/kg every 4–6 h IM or IV or as CRI)
  • Sodium sulfate (1 g/kg) or dioctyl sodium succinate (20 mg/kg, 2 doses over 48 h) can be used instead of magnesium sulfate as a laxative

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

The horse should be monitored closely during enteral fluid therapy or lavage as gastric rupture can occur. If signs of colic worsen or persist nasogastric intubation should be performed to check for reflux.

Prevention/Avoidance!!navigator!!

Depends on underlying cause. Instruction should be given to owners on how to correctly feed expandable feedstuffs to horses.

Possible Complications!!navigator!!

  • Gastric rupture
  • Peritonitis

Expected Course and Prognosis!!navigator!!

  • If gastric impaction does not resolve within 5 days after instituting medical treatment, it is unlikely to be successful. Surgical therapy should then be considered. If surgery is not feasible or declined by the owner the horse can potentially be managed with dietary recommendations. The surgery is difficult to perform and has a guarded prognosis.
  • Once dilation of the stomach has occurred, success of treatment (medical or surgical) is unlikely. Even if the impaction can be resolved, recurrence is likely.
  • Depending on the underlying cause prognosis varies. Recurrence has been reported and likely depends on the underlying cause

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

Chronic gastric ulceration (pyloric outflow stenosis).

Age-Related Factors!!navigator!!

  • Pyloric outflow stenosis due to gastric and pyloric ulcers is more common in foals <6 months of age.
  • Neoplasia of the stomach and resulting outflow obstruction is more common in older horses

Pregnancy/Fertility/Breeding!!navigator!!

N/A

Abbreviations!!navigator!!

  • CRI = constant rate infusion
  • GI = gastrointestinal
  • ICS = intercostal space
  • NSAID = nonsteroidal anti-inflammatory drug
  • US = ultrasonography, ultrasound

Suggested Reading ⬆ ⬇

Bird AR, Knowles EJ, Scherlock CE, et al. The clinical and pathological features of gastric impaction in twelve horses. Equine Vet Educ 2012;44(Suppl.):105–110.

Hurtado IR, Stewart A, Pellegrini-Masini A. Successful treatment for a gastric persimmon bezoar in a pony using nasogastric lavage with carbonated cola soft drink. Equine Vet Educ 2007;19:571–574.

LeJeune S, Whitcomb MB. Ultrasound of the equine abdomen. Vet Clin North Am Equine Pract 2014;30(2):353–381.

Vainio K, Skyes BW, Bilkslager AT. Primary gastric impaction in horses: a retrospective study of 20 cases (2005-2008). Equine Vet Educ 2011;23:186–190.

Author(s) ⬆

Author: Angelika Schoster

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa