If you go to
http://www.ferretcongress.org
and open the critical refs section by clicking on it you will find a
LOT of great links, including ones to lists of ferret vets.
 
(Check the site out; there is a LOT there and there will be even more in
the future; it is one of my 5 most used ferret sites when I need to seek
information and had links to the rest of them!  I keep it right on my
bookmarks bar for easy access.)
 
Liver values: the ALT levels go WAY off in ferrets when they don't eat.
Bilirubin is a more important value in ferrets.
 
See:
Confusion and Controversy in Interpreting Ferret Clinical Pathology Data
http://www.afip.org/ferrets/Clin_Path/ClinPath.html
 
Most specifically these paragraphs (which I have permission to 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.
[Posted in FML issue 4533]