Page 678 - Clinical Small Animal Internal Medicine

646 Section 7 Diseases of the Liver, Gallbladder, and Bile Ducts

VetBooks.ir Box 60.1 Clinical signs and clinical examination findings that may occur in animals with liver disease
Vague signs
Dysuria – relating to ammonium biurate urolithiasis
Vaguely “off form”
Lethargy Hematuria – relating to ammonium biurate urolithiasis
Copper‐colored iris (some cats)
Signs related to gastrointestinal tract Signs relating to disorders of hemostasis
Vomiting Gastrointestinal bleeding ‐ melena
Diarrhea Increased bleeding from invasive procedures
Anorexia Signs relating to the urinary tract
Weight loss Polyuria/polydipsia
GI bleeding ‐ melena Discolored urine – jaundice/hematuria
Signs related to cholestasis Dysuria (see above)
Jaundice May have prolonged recovery from sedation/general
Acholic feces ‐ with complete extrahepatic biliary anesthesia
obstruction Clinical findings
Signs related to hepatic encephalopathy Poor body condition score
Vague signs of dullness Mucous membrane pallor
Alterations in behavior Abdominal discomfort – organomegaly, abdominal
Ptyalism – particularly in cats distension, inflammation (hepatic/peritonitis/
Head pressing cholecystitis)
Disorientation Pyrexia – with some inflammatory, infectious or
Stupor neoplastic causes
Seizures Ascites ‐ relating to portal hypertension, hypoalbumine-
Vague neurologic signs, seizures or syncope may occur mia, biliary peritonitis or neoplastic effusion
with hypoglycemia Hepatomegaly +/‐ irregularity of liver margins – with
Signs relating to CPSS infiltration, some inflammatory conditions
Hepatic encephalopathy signs (see above) Skin lesions may be seen with hepatocutaneous
Stunting syndrome (superficial, necrolytic dermatitis)
Microhepatica

monitoring response to treatment. Occasionally, diag- enzymes. They are located mainly on hepatobiliary
nostic testing may allow definitive diagnosis of hepato- membranes and are markers of cholestasis or drug
biliary disease although more typically, it acts as a piece induction (see later). In general, the liver enzymes are
within the overall jigsaw. The biochemical tests directly sensitive indicators of liver disease or injury but are not
utilized in the evaluation of liver disease comprise the specific. There are far more animals in which elevated
liver enzymes and liver function tests, which appraise liver enzyme activities are detected than actually have
impaired metabolic function or synthetic capacity. clinically significant liver disease. This lack of specificity
However, evaluation of the full hematology and bio- arises from a combination of the susceptibility of the
chemistry panel is important to gain insight into the liver to secondary or “reactive” disorders, the ability of
animal’s general health. This aids clarification of the like- certain hormones or drugs, such as corticosteroids, to
lihood of another disease process that may either be the induce production of particular liver enzymes and the
cause of a secondary hepatopathy or represent an addi- presence of isoenzymes within tissues other than liver.
tional consideration in patient management. The clinical interpretation of the significance of liver
enzyme elevations is challenging and must always be
Enzyme Markers of Liver Disease considered in the context of the patent, its history, and
The liver enzymes evaluated can be divided into two the full clinical pathology results.
main groups dependent on their cellular location and It is important to realize that the liver enzymes do not
clinical utility. Alanine aminotransferase (ALT) and offer any indication of liver function. In an animal with a
aspartate aminotransferase (AST) are the two most com- primary hepatopathy, the magnitude of hepatocellular
monly measured markers of hepatocellular injury and enzyme release may broadly relate to the number of
are found primarily within the hepatic cytosol. Alkaline hepatocytes affected, particularly in the acute setting.
phosphatase (ALP) and gamma‐glutamyl transferase However, in view of the regenerative capacity of the liver,
(GGT) are the most commonly measured biliary the magnitude offers no prognostic information. It is also