Page 447 - Problem-Based Feline Medicine

21 – THE YELLOW CAT OR CAT WITH ELEVATED LIVER ENZYMES 439

Emaciated cats with advanced disseminated disease Cyclical vomiting and fever.
have a poor prognosis and they may not live long
Hepatomegaly may be palpable.
enough for the treatment to take effect.
Acholic feces are occasionally seen with complete
POST-HEPATIC CAUSES OF JAUNDICE obstruction.
OR INCREASED LIVER ENZYMES Acute pancreatitis may cause anorexia, lethargy,
abdominal pain and jaundice as a consequence of extra-
EXTRAHEPATIC BILIARY OBSTRUCTION hepatic biliary obstruction.
(EHBO)** PANCREATITIS** Pancreatic abscesses, cysts and neoplasia may cause
signs of extrahepatic biliary obstruction.
Classical signs

● Progressive anorexia, lethargy and marked
jaundice. Diagnosis
● Vomiting and fever may be episodic. Non-regenerative anemia and possibly a neutrophilic
● Hepatomegaly. leukocytosis are seen.
● +/- acholic feces.
Increased liver biochemical parameters are commonly
observed.
Pathogenesis ● Dramatic elevations in serum total bilirubin con-
centration. Elevations may occur as rapidly as
Obstruction of the extrahepatic biliary system has 4 hours following complete biliary obstruction.
diverse causes, including pancreatic disease, neoplasia, ● Increased ALP and GGT activities occur secondary
cholelithiasis and extrinsic compression (masses). to cholestasis. A 3–5-fold increase in GGT and
Consequences of biliary obstruction include cell mem- 2–10-fold rise in ALP are often present.
brane and organelle injury due to stagnation of bile ● Increased ALT (up to 10-fold) and 3–10-fold
acids and other injurious substances. Pancreatitis and increased AST activities reflect hepatocellular
neoplasia are the most common causes. injury.
● Pancreatitis may cause obstructive jaundice through
An antemortem diagnosis of pancreatitis causing
direct cholangiohepatic injury via refluxed pancre-
obstructive jaundice is elusive.
atic secretions, pancreatic fibrosis and/or obstruc-
● Variable leukocytosis with elevation of liver bio-
tion of the common bile duct within a few weeks
chemical parameters (total bilirubin, ALP, ALT) are
following pancreatic injury.
present.
● Neoplasia (e.g., pancreatic adenocarcinoma) may
● Recent studies show that elevation in feline
cause slowly progressive external compression of
pancreatic-like immunoreactivity assay (fPLI) may
the major bile ducts, resulting in obstructed biliary
provide presumptive serologic evidence of pancreati-
flow and jaundice.
tis. Serum fPLI appears to be more sensitive and more
Complete occlusion leads to cholestasis, hepatomegaly specific than serum feline trypsin-like immunoreactiv-
and dilatation of intrahepatic biliary structures. ity assay (fTLI) or abdominal ultrasonography.
● Ultrasonography demonstrates a generalized loss of
Obstruction of bile flow incites biliary tract/hepatocel-
pancreatic echogenicity with pancreatitis in most
lular inflammation and injury.
cases.
● Permanent biliary tract dilatation and hepatic fibro-
sis may be seen with chronic extrahepatic biliary Ultrasonography may confirm the presence of a pan-
obstruction. creatic mass and/or extrahepatic biliary obstruction
causing extrahepatic biliary obstruction.
Clinical signs ● Diagnosis of extrahepatic biliary obstruction is
confirmed on ultrasonographic evaluation or
Anorexia, lethargy and marked jaundice which are pro-
exploratory surgery.
gressive.