In patients with portosystemic shunts, twofold to threefold increases in serum ALP, ALT, and AST activities have been recorded
while patients with microvascular dysplasia may have normal to mild increases in these enzyme activities.20 Microcytic red blood cells are commonly noted in cases of portosystemic shunts but are not seen in cases of microvascular
dysplasia.
Gallbladder mucoceles
1. On this ultrasonogram, organized, striated, and immobile echogenic sediment can be seen within the gallbladder, consistent
with a gallbladder mucocele. The possibility of perforation should be considered given the surrounding effusion.
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Gallbladder mucoceles have been associated with mild to marked increases in serum activities of ALP, AST, ALT, and GGT.21 In a retrospective study examining gallbladder mucoceles, seven of 30 cases had no clinical signs of illness.21 In the 23 symptomatic cases, clinical signs were nonspecific and included vomiting, lethargy, and anorexia. The diagnosis
was made on abdominal ultrasonographic examination, which revealed immobile, echogenic bile with a striated or stellate pattern
within the lumen of the gallbladder (Figure 1).21 Cholecystectomy is recommended in these cases to prevent sequelae including cholecystitis, extrahepatic bile duct obstruction,
and gallbladder rupture.21
CONCLUSION
Increases in serum liver enzyme activities are sensitive indicators of hepatobiliary disease, but these activities can be
elevated secondary to various endocrinopathies, gastrointestinal disease, pancreatic disease, systemic disease, and enzyme
induction. In asymptomatic patients, a systematic approach is required to obtain a definitive diagnosis. A careful review
of the patient's history is essential to uncover vague clinical signs that the owner may have missed and to identify any potential
exposure to hepatotoxic agents. A complete minimum database, including a complete blood count and urinalysis, is required
to rule out an underlying extrahepatic disease. In some cases, sequential monitoring may be elected; however, persistent elevation,
marked elevations, concurrent increases in serum bilirubin concentrations, or concurrent decreases in albumin concentrations
warrant further investigation, including diagnostic imaging and, in many cases, hepatic biopsy.
Johanna Cooper, DVM
Cynthia R.L. Webster, DVM, DACVIM
Department of Clinical Sciences Cummings
School of Veterinary Medicine
Tufts University
North Grafton, MA 01536
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