Page 807 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

782 CHAPTER 4

VetBooks.ir Large intestine indicated. Its use is indicated in chronic or recurrent
colic, chronic undifferentiated GI disease and when
Large-colon impactions are usually located in the left
ventral colon and, less commonly, in the right dorsal
Decreases in serum proteins may be useful indica-
colon. As a general rule, feed impaction feels like firm the primary presentation of acute colic is atypical.
bread dough, which is easily indented by digital pres- tors of chronic GI disease. When performed blood
sure, but in which the impressions remain. The free work should include full haematological and bio-
tenial bands of the colon are palpable and run longi- chemical analysis plus fibrinogen and serum amyloid
tudinally. Sacculations are not palpable because of the A as a minimum database.
distension. With impaction of the right dorsal colon,
a mass can be felt in small horses in the right quad- NG intubation
rant. With gas or fluid distension, the colon can be NG intubation is an essential component of colic
indented, but the impression does not remain. A gas- examination in horses of all sizes. Passage of an
distended pelvic flexure is often displaced on the right appropriate-sized NG tube allows for identification
side or cranially. Oedema of the colonic wall is usu- and relief of accumulated fluid or gas in the stom-
ally indicative of large-colon torsion. Tympany and/ ach, identification of oesophageal obstruction, and
or impaction of the left colon with a band running provides an administration route for water, elec-
dorsally towards the nephrosplenic space is consistent trolyte solutions, mineral oil or other substances.
with left dorsal displacement of the large colon. The creation of a siphon, by priming the tube with
water, is required to confirm the presence of gastric
Small colon reflux as there is not always spontaneous reflux, even
Small-colon impaction is characterised by palpa- with severe gastric distension. Adequate manual or
tion of a doughy, sausage-like structure about 10 cm chemical restraint should be used to prevent injury
in diameter and usually longer than 30 cm. Other to the horse or veterinarian, and the positioning of
abnormalities that may be palpable on p/r examina- the tube in the oesophagus, not the trachea, should
tion include intraluminal foreign bodies, enteroliths be confirmed before anything is administered.
or intussusception.
Radiography
Rectum Abdominal radiography has limited applications
The absence of faeces or the presence of mucus- in adult horses and it is mainly used to identify
covered faeces indicates a decrease in GI transit, sand accumulation (including quantification and
which is often secondary to an obstructive disease. monitoring of treatment over time) or enteroliths.
If blood is present locally or on the rectal sleeve, the Radiography is more useful in foals and small horses.
rectum should be palpated carefully for the presence Gaseous distension of the stomach, small intestine
of a rectal tear. and large intestine, intestinal obstructions and the
presence of free gas in the abdomen can be identified
Others (Figs. 4.111, 4.112). A combination of lateral and
The peritoneal wall should be felt for roughening or ventrodorsal radiographs is most useful. Contrast
a gritty feeling, which will be an indication of peri- radiography is often used for the diagnosis of meco-
tonitis following bowel rupture. nium impactions, but it can also be used to assess
intestinal patency and gastric emptying.
DIAGNOSTIC TESTS
Ultrasonography
Haematology and biochemistry Ultrasonographic examination can be very useful in
Haematology is of variable usefulness in the inves- the diagnosis of GI disease, although its limitations
tigation of GI disease. In acute, once-off episodes must be recognised. The main limitation, beyond
of colic it is typically unremarkable or the changes inexperience of the ultrasonographer, is that there
are non-specific, and as such it is commonly not is only adequate penetration of 25–30 cm. Intestinal