Quoting Dr. Bruce Williams, a ferret pathology expert (with his
permission):

BEGIN QUOTE
Probably the most common misinterpretation that I see on a routine
basis is in the area of hepatic enzymes. Remember, that the ferret,
being by nature an obligate carnivore, has an extremely short digestive
tract, and requires meals as often as every four to six hours. Should
food not be available, it possesses the ability to quickly mobilize
peripheral fat stores in order to meet energy requirements. When this
physiologic mechanism is activated, the liver is literally flooded with
fat, which results in hepatocellular swelling which may be marked. The
result of this swelling is the leakage of membrane enzymes such as
alanine aminotransferase, and as the hepatocellular swelling increases,
occlusion of bile canaliculi occurs, resulting, over time, in elevation
of alkaline phosphatase.

In conjunction with this physiologic change, elevations of ALT up to
800 mg/dl can be seen, and alkaline phosphatase up to approximately
100 mg/dl. This often causes confusion to practitioners, who render an
erroneous diagnosis of unspecified hepatic disease. However, hepatic
disease is quite uncommon in this species; the most common cause of
true hepatic disease in the ferret is neoplasia, with lymphosarcoma
causing 95% of cases. Rarely bacterial infections of the liver or
biliary tree may be seen.

The diagnosis of hepatic disease in the ferret must be based not only
on ALT and alkaline phosphatase, but other clinical indicators in the
CBC and chem panel. Clinical elevation of icterus or an elevated
bilirubin is an excellent indicatior of primary hepatic disease, or
concomitant leukocytosis or pyrexia may lend additional credence to
a diagnosis of primary hepatic disease.

END QUOTED SECTION

Dr. Bruce Williams is a ferret veterinary pathology expert, one of the
world's best.

So, what is the bilirubin like?

[Posted in FML 7908]