Page 835 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

810 CHAPTER 4

VetBooks.ir production, then gastric dilation occurs. When an obstructive small-intestinal lesion is present. If
If aboral movement of gas does not equal
primary gastric dilation is suspected, diet and man-
the stomach is distended, the conformation of the
gastro- oesophageal junction changes so that the agement should be evaluated.
cardiac sphincter is tightly closed, and fluid and gas Prognosis
cannot move from the stomach into the oesophagus. The prognosis depends on the cause. The prog-
As dilation increases, signs of colic may develop. nosis for primary gastric dilation is excellent. The
prognosis for secondary dilation depends on the
Clinical presentation severity of the inciting lesion. The presence of
Non-specific signs of colic are most commonly spontaneous gastric reflux is a very poor prognostic
observed. Pain may be severe and heart rate may be indicator because of the typical severity of disease
markedly elevated (>100 bpm) if the stomach is very and the potential for complications such as aspira-
distended. Tachypnoea may be present because of tion pneumonia.
compression of the thoracic cavity by a large, dis-
tended stomach. Other clinical abnormalities may GASTRIC IMPACTION
relate to the underlying disease process in horses
with secondary gastric dilation. Definition/overview
Gastric impaction is an uncommon cause of colic.
Differential diagnosis
Other causes of colic should be investigated. Aetiology/pathophysiology
Particular attention should be paid to small- intestinal Accumulation of excessive amounts of ingesta in
disorders that may result in gastric distension. the stomach from a variety of causes may result in
gastric impaction (Fig. 4.139). Impacted ingesta
Diagnosis become dessicated, firm and resistant to rehydration.
Gastric dilation is identified and relieved by passage Gastric distension may result in signs of abdominal
of a NG tube as part of a thorough colic evaluation. pain. Many cases are idiopathic. Dental disorders,
In uncomplicated cases, relief following passage of EGUS, poor-quality diet, abnormal GI motility
the NG tube should result in near complete reso- (e.g. grass sickness) and gastric outflow obstruction
lution of clinical signs and the presence of ongoing may be associated with gastric impaction. Gastric
pain or tachycardia should prompt further evaluation impactions may occur concurrently with large-colon
of other differentials. No abnormalities are typically impactions.
detectable p/r unless gastric dilation is secondary to
a small-intestinal lesion; however, marked gastric
dilation can displace the spleen caudally. Gastric
distension may be evident ultrasonographically. 4.139
A thorough evaluation for small-intestinal lesions is
warranted.

Management
Decompression of the stomach and resolution of the
primary cause, if present, are the most important
components of treatment. If a large volume of gas or
fluid reflux is obtained, the NG tube should be left
in place or intubation repeated as often as hourly.
The NG tube can be removed once gas and fluid
reflux are minimal. Surfactants such as DSS are not Fig. 4.139 Gastric impaction. Note the large mass of
effective. Surgical intervention may be required if dry ingesta in the stomach.