Page 680 - Problem-Based Feline Medicine

672 PART 9 CAT WITH SIGNS OF GASTROINTESTINAL TRACT DISEASE

Lymphocytes and plasma cells are normal compo- It is especially important to rule out parasitic, infec-
nents of the feline GI tract, and increased numbers in tious, dietary and extra-intestinal (e.g. hepatic, renal
the GIT occur in response to many infectious agents. or pancreatic) causes of disease, as these may cause
Differentiation of feline IBD from other diseases similar lesions to IBD.
requires a complete examination to rule-out other
The only means of ruling out dietary causes of vomit-
causes for the infiltration. In IBD, there should also
ing is via an elimination trial, which must be conducted
be evidence of mucosal disease (e.g. erosion, villous
using an elimination diet prior to making a diagnosis of
blunting, loss of normal structure in other ways, loss of
IBD.
normal function).
Endoscopic examination and biopsy is the most com-
Eosinophilic IBD is rare in cats, and in some cases it
mon procedure used to obtain the diagnosis. Multiple
is found in association with hypereosinophilic syn-
(6–8), good-quality (containing submucosa and prop-
drome (infiltration of eosinophils in many body tissues
erly oriented) biopsies should be obtained from the
including liver, spleen, lymph nodes, etc.).
small intestine and stomach. Biopsies should be taken
Other forms of IBD, such as granulomatous and neu- from all regions of the stomach and lymphoid follicles
trophilic IBD are also rare in cats. should be avoided when obtaining biopsies from the
duodenum. Full-thickness biopsies obtained surgically
Most forms of IBD involve the small intestine, spar-
are also acceptable if endoscopy is unavailable, and
ing the stomach and colon, however, enterocolitis and
equal care should be taken to assure biopsy quality
gastritis may also occur.
(proper handling to minimize artifact and orientation on
Recently an association has been observed between the biopsy sponge to prevent curling and crush artifacts).
cats with idiopathic IBD and concurrent cholangitis
The major difficulty associated with endoscopic
and pancreatitis. The true relationship between these
diagnosis of IBD is differentiation of IBD from lym-
observations and clinical IBD is not known.
phoma, which will not be possible if the biopsy sam-
ples are not deep enough (contain submucosa) or if they
Clinical signs have significant mucosal artifacts that prevent adequate
assessment of mucosal abnormalities. In some cases
Vomiting and weight loss are the most common
where histologic differentiation is impossible, immuno-
signs, but diarrhea and anorexia are also frequently
cytochemistry techniques may have to be employed to
observed signs.
distinguish the cell origin (e.g. lymphoma cells tend to
Middle-aged (> 4 years) cats are most frequently be monoclonal, while lymphocytes from cats with IBD
affected, but all ages have been reported to have IBD. will be polyclonal).
There is no breed or sex predilection, but purebred Non-specific laboratory abnormalities that may be
cats may be at increased risk compared to DSH cats. found in cats with IBD include: hypoproteinemia,
hyperglycemia (stress induced), hypokalemia, ele-
If there is concurrent cholangitis or pancreatitis, cats
vated liver enzyme activities and a stress leukogram.
may also present with icterus, abdominal pain or fever.
Serum cobalamin and folate levels may be decreased
in cats with IBD due to malabsorption.
Diagnosis
Radiography and ultrasonography generally do not
The diagnosis is based upon several factors: (1) his-
assist with the diagnosis, but are important in ruling
tologic infiltration of inflammatory cells, usually lym-
out other causes of the clinical signs, e.g. neoplasia.
phocytes and plasma cells in the GI tract; (2) the
presence of inflammatory cells is associated with
mucosal abnormalities and functional disturbances; Differential diagnosis
(3) there are no other identifiable causes for the infil-
tration identified; and (4) the signs of the disease are Neoplasia (lymphoma is of special mention because
chronic (> 3 weeks in duration). it may have a similar histologic appearance to IBD).