Page 560 - Small Animal Internal Medicine, 6th Edition

532 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

BOX 34.1 BOX 34.2
VetBooks.ir Summary of Biochemical Tests for the Hepatobiliary Summary of Biochemical Tests for the Pancreatitis and to
Assess the Associated Systemic Inflammatory Response
System and Their Relevance to Assess Function
Tests for liver involvement (primary Tests for liver function or Pancreatic Function
or secondary) Tests for pancreatitis Tests for pancreatic function
Liver enzymes: predominantly Nonspecific: Relatively specific Tests for exocrine function:
hepatocellular (but overlap with • Total protein and • Pancreatic lipase • Trypsin-like
hepatobiliary—see text) albumin/globulin immunoreactivity (species immunoreactivity
• Alanine aminotransferase ratio* specific tests) (reduced)—species
• Aspartate aminotransferase • Coagulation tests* • Lipase and DGGR lipase* specific
• Urea • Trypsin-like • Fecal elastase (rarely
• Glucose immunoreactivity (elevated) used)
• Cholesterol † (species specific—Poorly • Cobalamin (reduced
Liver enzymes: predominantly More specific tests of sensitive; more specific for due to lack of
hepatobiliary (but overlap with function and/or pancreatitis in dog than pancreatic intrinsic
hepatocellular—see text) portosystemic shunting cat) factor)
• Alkaline phosphatase • Bile acids pre- and • Serum elastase— rarely
• Gamma-glutamyltransferase poststimulation † used
• Ammonia • Amylase—poor sensitivity
Bilirubin Relatively specific tests of and specificity
function only and not Nonspecific tests which assess Tests for endocrine function
portosystemic shunting systemic inflammatory response • Blood glucose
• Bilirubin* ,† and associated organ failure (see • Urine glucose and
text) ketones
*Also prognostic indicators when interpreted correctly—see text. • Complete blood count— • Fructosamine
† Only useful tests of function in an animal with no evidence of particularly neutrophil and
cholestasis. platelet counts
• Urea and creatinine with
concurrent urine SG
• Electrolytes: particularly
Most importantly, before an accurate prognosis can be potassium; sodium;
given, a complete evaluation must be conducted, including, calcium
for most primary hepatobiliary diseases in dogs and cats, a • Liver enzymes
liver biopsy. • Bilirubin
DIAGNOSTIC APPROACH TO *DGGR lipase more specific than traditional lipase—see text
PANCREATIC DISEASE
The use of appropriate clinicopathologic tests in a dog or cat
with typical clinical signs can help in the diagnosis of pan- DIAGNOSTIC TESTS PREDOMINANTLY
creatitis, but some form of diagnostic imaging is advisable to TO ASSESS THE STATUS OF THE
confirm this. Secondary causes of enzyme elevation are less HEPATOBILIARY SYSTEM
common in the pancreas than in the liver. Nonetheless, pan- A summary of laboratory tests for cats and dogs with hepa-
creatitis may not be the most clinically significant disease in tobiliary disease and interpretation of the results are given
an individual sick animal, and diagnostic imaging is impor- in Table 34.1.
tant to rule out other causes of acute abdomen with second-
ary pancreatic involvement such as gastrointestinal (GI) Serum Liver Enzyme Activities
obstruction or gallbladder rupture. More general clinico- Liver-specific serum enzyme activities are included routinely
pathologic tests also allow assessment of the degree of con- in screening serum biochemistry panels and are regarded as
current systemic inflammatory response and evidence of markers of hepatocellular and biliary injury and reactivity.
multiorgan failure in severe acute pancreatitis (Box 34.2). In However, this can be due to primary liver disease or second-
more chronic pancreatitis, exocrine and/or endocrine func- ary to other disease particularly in the splanchnic bed. Hepa-
tional impairment can occur and are assessed as indicated in tocellular enzymes are increased in more than 60% of dogs
Box 34.2 in addition to clinical signs. Exocrine function is and cats with acute pancreatitis, and cholestatic markers are
also impaired in pancreatic acinar atrophy (PAA). A fecal increased in more than 60% of dogs and cats with acute
sample is an important addition to the diagnostic panel in pancreatitis.
dogs with diarrhea associated with pancreatic disease to rule Because marked hepatic disease can be present in patients
out infectious causes of the clinical signs, particularly as dogs with normal serum enzyme activity, finding normal values
with PAA tend to be younger animals also more predisposed should not preclude further investigation, especially if there
to GI parasites. are clinical signs or other laboratory test results that suggest