Page 836 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 811

VetBooks.ir Clinical presentation Prognosis
Gastric impactions can be frustrating because of
Non-specific signs of colic will be displayed, rang-
ing from mild to severe. Heart rate will be elevated
consistent with the degree of pain. Signs of toxaemia the time required for some impactions to resolve.
However, provided a serious primary problem such
or cardiovascular compromise should not be evident. as grass sickness or pyloric obstruction is not present,
the prognosis is good. If reoccurrence does occur
Differential diagnosis then the long-term prognosis is poor, although some
A variety of other causes of acute colic must be con- animals can be managed on low bulk diets.
sidered. Primary gastric impaction should be dif-
ferentiated from gastric impaction secondary to PYLORIC STENOSIS
abnormalities of gastric motility or gastric outflow
such as pyloric stenosis and grass sickness. Definition/overview
Pyloric stenosis is a rare condition that results in
Diagnosis delayed gastric outflow.
Medical diagnosis of gastric impaction is diffi-
cult. Difficulty passing a stomach tube through Aetiology/pathophysiology
the cardia may suggest that gastric distension Pyloric stenosis may be a congenital lesion or occur
is present. Palpation p/r is usually unremark- secondary to severe gastric and duodenal ulceration,
able. Abdominocentesis is normal unless gastric particularly in foals, weanlings and yearlings. If gas-
rupture has occurred. Gastroscopy is very use- tric outflow is inhibited, accumulation of food mate-
ful. It can be difficult to differentiate an impac- rial and gastric acid will occur.
tion from a full stomach but if feed has been
withheld for 18–24 hours and a large volume of Clinical presentation
feed material is still present, then an impaction is Intermittent colic, lethargy and chronic weight loss
likely. are the most common clinical signs. Salivation,
bruxism and anorexia may also be present.
Management
Affected horses should be kept off feed until the Differential diagnosis
impaction has resolved; however, free access to water EGUS and duodenal ulceration are the main differ-
should be provided. A NG tube should be left in place ential diagnoses; however, all other causes of weight
or passed frequently. Administration of 10–20 ml/kg loss and chronic colic should be considered.
balanced electrolyte solution via a NG tube should
be performed every 2–4 hours. Care should be taken Diagnosis
not to use too much pressure when infusing water to Haematological changes, if present, are non-specific.
lessen the chance of gastric rupture. Gravity flow is Palpation p/r and abdominocentesis are usually nor-
preferred over the use of hand pumps. If the horse mal. NG reflux may be present depending on the
appears to be in pain, infusion should be stopped. severity of gastric outflow disruption. EGUS will
The use of carbonated beverages has been recom- be evident endoscopically, but it will not be possible
mended but is of little benefit aside from cases of to determine whether it is primary or secondary.
persimmon seed impaction. Bethanecol (0.02 mg/kg An attempt should be made to enter the duodenum.
s/c q6–8 h) has been recommended; however, there Ultrasonographic examination of the abdomen can
is a theoretical increased risk of gastric rupture and be used to assess gastric distension, duodenal thick-
it appears to offer little benefit over frequent infu- ness and duodenal motility. Other methods to evalu-
sion of fluids alone. Gastroscopy should be used to ate gastric emptying include nuclear scintigraphy,
evaluate response to treatment and confirm that the oral glucose absorption testing and paracetamol
impaction has passed. Risk factors should be identi- (acetaminophen) absorption testing. Barium radi-
fied and addressed. ography has been used to evaluate gastric emptying