Page 316 - Problem-Based Feline Medicine

308 PART 6 CAT WITH WEIGHT LOSS OR CHRONIC ILLNESS

When lymphangectasia is present, severe hypopro- ● Survey radiographs tend to be unrewarding, but
teinemia may lead to subcutaneous edema and/or may reveal gas- or fluid-filled loops of intestines.
ascites. Barium studies may reveal flocculation or per-
sistent adherence of the barium to the mucosa,
irregular mucosal surfaces or delayed transit
Diagnosis times.
● Ultrasound examination may reveal intestinal
Before a diagnosis of IBD can be made, all other
wall irregularity or echogenicity. It may also be
causes of enteropathy must be ruled out. These include
used to examine the mesenteric lymph nodes and
bacterial enteritis (Helicobacter spp., Salmonella spp.,
other intra-abdominal structures.
Campylobacter spp., Clostridium perfringens, E. coli),
● Serum folate and cobalamin levels may be
intestinal parasites (helminths, cestodes, protozoans),
reduced because of malabsorption.
fungal enteritis, GI neoplasia (lymphosarcoma, adenocar-
● Serum feline trypsin-like immunoreactivity
cinoma) and viral enteritis (feline leukemia virus, feline
(fTLI) and feline pancreatic lipase immunoreac-
immunodeficiency virus, feline coronavirus, feline pan-
tivity (fPLI) may be helpful in the diagnosis of
leukopenia). IBD is diagnosed by documenting
exocrine pancreatic insufficiency (EPI) and pancre-
histopathological evidence of GI inflammation and
atic inflammation, respectively.
excluding all of other causes of it.
● Breath hydrogen analysis and sugar permeability
Baseline laboratory tests include hematology, serum studies may be used to try to demonstrate malab-
biochemistry (including total T4 concentration in older sorption and/or small intestinal bacterial overgrowth
cats), FeLV and FIV tests, urinalysis, fecal culture for (SIBO)/antibiotic-responsive diarrhea.
pathogenic bacteria and a full examination for fecal
A dietary trial should be performed in all except very
parasites.
ill patients prior to more invasive investigation.
● Performing all of these investigations can be expen-
● Feed a single highly digestible source of protein for
sive so the investigation should, where possible, be
at least 3–4 weeks and see if the clinical signs
tailored to the patient, and many clinicians start
resolve.
with a dietary trial (see below).
● Since the investigations are being performed to rule It is inadvisable to carry out treatment trials with
out other causes of enteropathy they are frequently antibiotics or corticosteroids prior to making a
unremarkable. However, IBD may be associated definitive diagnosis.
with a number of non-specific findings: ● This delays making the correct diagnosis, and may
– Hematology may reveal an inflammatory cause complicating intestinal bacterial overgrowth
response; neutrophilia, eosinophilia, lymphope- (antibiotics) or potentiate secondary infections
nia or monocytosis. Microcytic anemia may (corticosteroids).
result from chronic blood loss associated with
Definitive diagnosis requires the collection of intes-
severe IBD.
tinal biopsies.
– Hyperglobulinemia may result from chronic
● Mucosal biopsies may be collected by endoscopy.
inflammation. Panhypoproteinemia may be
Unfortunately, it is not always possible to make a
seen with severe protein-losing enteropathies.
definitive diagnosis from these biopsies, so in some
– Increases in liver enzymes may result from
cases, full-thickness biopsies must be collected via
associated hepatic inflammation (see below).
laparotomy or laparoscopy.
Non-invasive screening tests may provide additional ● IBD often causes no gross mucosal changes, but
information. These include abdominal radiography, changes that may be seen include increased granu-
ultrasound examination, assessment of serum folate larity and friability, the presence of erythema, ulcer-
and cobalamine (B12) levels, examination of fecal ations, and/or mass lesions and poor distensibility.
smears for the presence of undigested fats or starch, fat ● Multiple biopsies should be taken since the
absorption tests, breath hydrogen analysis and sugar inflammatory infiltrates may not be spread dif-
permeability studies (where available). fusely throughout the gastrointestinal tract.