Page 440 - Small Animal Internal Medicine, 6th Edition

412 PART III Digestive System Disorders

CHAPTER 27
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Diagnostic Tests for the

Alimentary Tract

PHYSICAL EXAMINATION infection (e.g., aspiration pneumonia), or anemia (e.g.,
pale mucous membranes, melena, hematemesis) and also
Routine physical examination is the first step in evaluating in those that have fever, severe weight loss, or hyporexia of
animals with alimentary tract disease. If oral, abdominal, or occult cause. The clinician should always consider absolute
rectal disease is a concern and the patient refuses to allow numbers of the different types of white blood cells. If the
examination of the area, it is usually appropriate to use animal is anemic, the clinician should look for evidence of
chemical restraint to adequately examine the area. A common regeneration (i.e., reticulocytes, polychromasia) and iron
example is a vomiting cat with a possible linear foreign body deficiency (e.g., hypochromasia, microcytosis, increased red
lodged under the tongue; the clinician should thoroughly blood cell distribution width).
examine the mouth and base of the tongue, even if it requires
strong sedation. COAGULATION
The clinician should methodically identify individual Platelet numbers can be estimated from a blood smear. A
organs during abdominal palpation. In dogs the small intes- dog should have 8 to 30 platelets per oil immersion field;
tine, large intestine, and urinary bladder can usually be finding 1 platelet per field suggests a platelet count of approx-
found (unless there is pain, effusion, or obesity). In cats both imately 15,000 to 20,000/µL. Coagulation panels may detect
kidneys are usually palpable. In both species clinicians unsuspected coagulopathies (e.g., disseminated intravascu-
should usually be able to detect substantial splenomegaly, lar coagulation). Activated clotting times are crude estimates
hepatomegaly, intestinal or mesenteric masses, and intestinal of the intrinsic clotting pathway; partial thromboplastin
foreign objects. Abdominal pain may be subtle; some animals times are more sensitive. Mucosal bleeding time is an excel-
cry out during gentle palpation, whereas others just tense lent screening test for coagulopathies severe enough to cause
their abdomen (i.e., guarding) or try to move away. Rough clinical bleeding.
palpation technique can cause a normal animal to tense up
or vocalize during palpation, mimicking abdominal pain. SERUM BIOCHEMISTRY PROFILE
Light, careful palpation permits the definition of more of the Serum alanine transaminase, alkaline phosphatase, blood
abdominal contents. If there is sufficient abdominal fluid to urea nitrogen, creatinine, total protein, albumin, sodium,
prevent meaningful abdominal palpation, ballottement of potassium, chloride, total CO 2 , cholesterol, calcium, phos-
the abdomen should produce a fluid wave. phorus, bilirubin, and glucose concentrations are important
During digital rectal examination, the examiner should to evaluate in animals with severe vomiting, diarrhea, ascites,
be able to identify and evaluate the colonic mucosa, anal unexplained weight loss, or hyporexia. Clinicians cannot
sphincter, anal sacs, pelvic canal bones, muscular support for predict changes that will occur or the magnitude of changes
the rectum, urogenital tract, and luminal contents. It is easy in a particular animal, even when the cause of the disease is
to misinterpret small mucosal polyps as mucosal folds known. The total CO 2 concentration is not as definitive as
and to miss partial strictures large enough to allow a single blood gas analysis for defining acid-base, but it typically
digit to pass through easily. suffices.
The serum albumin concentration is more useful than
serum total protein concentration. Hyperglobulinemia
ROUTINE LABORATORY EVALUATION has many causes (e.g., heartworms, chronic dermatitis,
ehrlichiosis) and can cause the serum total protein concen-
COMPLETE BLOOD COUNT tration to be normal in hypoalbuminemic patients. Severe
Complete blood counts are important in animals at risk hypoalbuminemia (i.e., <2.0 g/dL) is important diagnosti-
for neutropenia (e.g., parvoviral enteritis, severe sepsis), cally; it is more commonly found in animals with intestinal

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