Page 428 - Small Animal Internal Medicine, 6th Edition

400 PART III Digestive System Disorders

Diarrhea plus weight loss (no hematochezia)
VetBooks.ir History/physical examination

Rule out parasitism, especially giardiasis
(multiple fecal examinations empirical therapy)

Rule out obvious dietary problems
(e.g., poor-quality food, table scraps, access to trash)

CBC, serum chemistry panel, serum TLI, serum cortisol (dogs)
(FeLV, FIV, and serum free thyroxine concentration in older cats)

Serum albumin < 2.0 g/dL Low TLI Nonprotein-losing enteropathy
(serum albumin concentration normal)
Rule out hepatic and renal Exocrine pancreatic insufficienty
causes of hypoalbuminemia EITHER

Protein-losing enteropathy: Empirical therapy Diagnostic tests
Abdominal ultrasound plus
(depending upon geographic area)
antigen tests for histoplasmosis, Elimination diet
heterobilharzia, and pythiosis Antibacterial drugs

Gastroduodenoscopy colonoileoscopy If not successful...
and intestinal biopsy (preferred to Abdominal ultrasonography
empirical therapy in most cases)
Exploratory Gastroduodenoscopy
laparotomy
Colonoileoscopy

FIG 26.4
General diagnostic approach to small intestinal diarrhea in the dog and cat. CBC,
Complete blood count; FeLV, feline leukemia virus; FIV, feline immunodeficiency virus, TLI,
trypsin-like immunoreactivity.

is not emaciated or rapidly losing weight and is not hypoal- always precede biopsy because it may be diagnostic if it
buminemic, then biopsy is seldom the best next step. Screen- shows dilated lymphatics in the intestinal mucosa (i.e., lym-
ing for atypical hypoadrenocorticism with resting serum phangiectasia) or lymphadenopathy or intestinal infiltrates
cortisol concentrations is appropriate. Testing for histoplas- that can be aspirated percutaneously. If ultrasonography is
mosis, pythiosis, and heterobilharziasis can be appropriate, not diagnostic, then biopsy is the next step (Boxes 26.9 and
depending upon geographical location. Therapeutic trials 26.10). Either laparotomy or endoscopy can be performed
are the best way to diagnose dietary-responsive diarrhea and to biopsy the bowel. If ultrasonography reveals a localized
ARE (also called antibiotic-responsive diarrhea and/or dys- lesion that cannot be reached with an endoscope, then lapa-
biosis), which are two of the most common causes of chronic rotomy is indicated. Otherwise, endoscopy is quicker and
small bowel diarrhea in dogs. ARE cannot be diagnosed by safer than laparotomy and may allow the clinician to biopsy
measuring serum cobalamin and folate concentrations. If lesions not discernable from the serosal surface. Endoscopic
a therapeutic trial is performed, the clinician must be sure biopsy specimens can easily be nondiagnostic if the endos-
that it is done properly (e.g., long enough, correct dose) so copist has not been carefully trained in biopsy techniques.
that it has a high likelihood of succeeding if the animal has If laparotomy is performed in hypoalbuminemic animals, it
the suspected disease. If the patient seems particularly ill may be prudent to use nonabsorbable suture material and/
(e.g., severe or rapid weight loss), or is hypoalbuminemic, or perform intestinal serosal patch grafting. Distended intes-
or has failed well-implemented clinical trials and is negative tinal lymphatics or lipogranulomas in the intestinal wall are
for infectious causes (i.e., histoplasmosis, heterobilharziasis, suggestive of lymphangiectasia. If intestinal biopsy speci-
pythiosis) and atypical hypoadrenocorticism, then abdomi- mens are not helpful, the main possibilities are that the tissue
nal ultrasonography is the next step. Ultrasonography should specimens were inadequate (e.g., not deep enough, from