Page 455 - Small Animal Internal Medicine, 6th Edition

CHAPTER 27 Diagnostic Tests for the Alimentary Tract 427

specimens of the gastric and duodenal mucosa should always
be obtained because normal gross findings do not rule out
VetBooks.ir severe mucosal disease. Like esophagoscopy, gastroduode-
noscopy is not sensitive in identifying functional problems
(i.e., gastric hypomotility).
Proctoscopy or colonoscopy is indicated in dogs and cats
with chronic large bowel disease unresponsive to appropriate
dietary, antibacterial, or anthelmintic therapies as well as
those that are losing weight, are hypoalbuminemic, or are at
increased risk for specific diseases (e.g., histiocytic ulcerative
colitis in Boxers). Colonoscopy plus biopsy is more sensitive
and definitive for infiltrative diseases than imaging. Proctos-
copy is used in animals with obvious rectal abnormalities
(e.g., mass or stricture felt on digital rectal examination).
Rigid biopsy forceps obtain excellent tissue samples that
FIG 27.16 allow identification of most lesions, including submucosal
Endoscopic view of the stomach of a dog with an obvious ones. Biopsy instruments used with flexible endoscopes do
mass in the greater curvature. This is an ulcerated not obtain as deep a tissue specimen but are adequate for
leiomyosarcoma that was successfully removed. sampling mucosal lesions.
Proctoscopy and colonoscopy are easier to perform,
require less restraint, and do not always require the more
expensive flexible equipment demanded by other endoscopic
procedures. The colon must be clean to allow proper inspec-
tion of the mucosa. All food should be withheld for at least
36 and preferably 48 hours before the procedure, a mild
laxative (e.g., bisacodyl) should be administered the night
before the procedure, and several copious warm water
enemas should be given the night before and the morning of
the procedure. Proctoscopy requires less cleaning than
colonoscopy. Commercial intestinal lavage solutions (e.g.,
GoLytely, CoLyte) clean the colon better than enemas and
are particularly useful in larger dogs, those that will be
undergoing ileoscopy (which necessitates a very clean ileo-
colic area), and animals in pain that resist enemas. The lavage
solution is usually given to the animal twice the night before
FIG 27.17 the procedure and perhaps once the morning of the proce-
Endoscopic view of the stomach of a cat with diffuse dure. In rare cases, it can cause gastric dilation or volvulus,
inflammation, erosion, and ulceration of unknown cause.
and inadvertent aspiration can be devastating.
Occasional dogs with substantial colonic irritation strain
so much that they essentially clean themselves out, and
colonoscopy can be performed without cleansing enemas
or lavage solutions. These same patients can sometimes be
scoped with just manual restraint or mild sedation (Video
27.1). However, many animals undergoing colonoscopy
have colonic or rectal irritation, and anesthesia is usually
preferred.
Normal colonic mucosa is smooth and glistening, and
submucosal blood vessels should be seen (Fig. 27.22). Enema
tubes may cause linear artifacts. The colon should distend to
a uniform diameter, but it may have bends. If a flexible scope
is used, the clinician should identify and inspect the ileoco-
lic valve and the cecum (Figs. 27.23 and 27.24). The clini-
cian should always biopsy the mucosa. While some patients
with neoplastic or inflammatory infiltrative diseases have
FIG 27.18
A focal gastritis near the pylorus of a dog. Note the obvious bruising (Video 27.2), normal gross findings do not
reddened spots on the lesion, which were responsible for rule out significant infiltrative disease. Strictured areas with
intermittent hematemesis. relatively normal-appearing mucosa are usually caused by a