Gastric Impaction - Horse
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Description
Gastric impaction can occur as a primary condition but is often diagnosed at surgery as a finding secondary to other disturbances in the intestinal tract. In some cases there be predisposing causes such as ulceration or fibrosis at the pylorus, whereas in other cases it may occur spontaneously.
Aetiology
Impaction of the stomach typically consists of excessive dry, fibrous ingesta, but may also be composed of ingested materials that form a mass, suchas persimmon seeds or mesquite beans.1-3 Other feeds that tend to swell after ingestion, including wheat, barley, and sugar beet pulp, may also cause impaction. Furthermore, dental disease may increase the likelihood of gastric impaction because of improper chewing of feed. (Bliks)
Predisposing factors
- Ingestion of certain feedstuffs including beet pulp, bran, straw, wheat and barley - beet pulp and bran can become dessicated within the stomach and may not become rehydrated by water or gastric secretions
- Dental disorders - roughage may be incompletely masticated
- Feeding a horse that has signs of colic - there may be poor gastric emptying associated with generalised decreased gastrointestinal motility
Clinical signs
Abdominal discomfort If the signs are mild and resolve spontaneously or with analgesics, owners often inclined to feed the horse, worsening the impaction
Diagnosis
Suspected if cannot pass NGT, with gastric distension the gastoroesophageal junction can become distorted making it difficult to pass an NGT If poorly macerated or digested feed material is recovered from the NGT when the horse has been starved for several hrs On rectal, spleen may be displaced caudally and medially (not specific) Endoscopy (not diagnostic for impaction and difficult to assess gastric distension) Rads may help, will show diaphragm displaced cranially
Treatment
If suspected, horse should be tranferred with NGT in place to a faciltiy where surgery can be perfomed if necessary Medical tx can include gastric lavage to remove as much impacted material as possible - may need to be done repeatedly 100-200ml 8%DSS may facilitate hydration of dessicated ingesta IV fluid and anlagesics should also be given, although unlikely that IV fluids will resolve the impaction Gastric motility stimulants should be avoided if the extent of the impaction is unkown to prevent gastric rupture Those diagnosed at sx may be treated with bethanecol at 0.2mg/kg SC every 8hrs
Surgery Direct infusion of balanced polyionic fluids into the impaction through the stomach wall Stomach massaged to break down impaction and facilitate movement of fluid into the ingesta Or fluid may be infused via NGT followed by massage of the stomach Post-op starve for 48-72hrs Gastroscopy indicated to confirm resolution of impaction and identify any underlying causes in stomach
References
Mair, T.S, Divers, T.J, Ducharme, N.G (2002) Manual of Equine Gastroenterology, WB Saunders.