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Interpreting the serum chemistry profile in ferrets (Proceedings)


While the ferret is not considered to be a particularly exotic pet and in general its clinical medicine is very similar to feline clinical medicine, the interpretation of the ferret chemistry profile deserves special attention as there can be several pitfalls if ferret profiles are interpreted by comparing with cat or dog normal values. This lecture and handout will focus on some of the most important clinical pathology parameters and their interpretation.

As in other species, an exact diagnosis of a clinical problem should never be based on blood work alone, but should include an evaluation of other diagnostic tools such as biopsies. One abnormal parameter is rarely pathognomic for a problem, and often 2 or 3 clinical pathology parameters need to be assessed in order to better locate the potential origin of the clinical problem, especially if it is sub-clinical. If several different parameters are significantly altered a preliminary diagnosis can be with a high degree of certainty and then pursued with further diagnostics. Further diagnostics approaches, e.g. biopsies, should be recommended.

The recommended reading for a detailed discussion on GI and liver diseases of ferrets is the AFA proceeding 2006 (Burgess M. 2006).

Parameters to evaluate different organ function:

Pancreas

  • Glucose:

     o Normal values 90-200 mg/dl
     o An extremely important parameter, as insulinoma is the most common form of cancer affecting the ferret in the USA.
          • Extremly common in ferrets older then 4 years and the blood glucose should be checked at least once a year.
     o Care has to be taken when using a human glucosometer as these devices will artificially read out lower values then the true value, usually 15-20 mg/dl lower).
          • In addition the (in)accuracy of these units is around 20 mg/dl.
     o The fasting glucose (4-6 hr fast) should be between 90-120 mg/dl.
     o If animal has been fasting for longer periods of time, the glucose will be low and is not considered diagnostic for insulinoma.
     o If the animal was eating with the last 4 hours and the glucose is below 90 mg/dl (< 60 mg/dl on the human glucometer) this is diagnostic for insulinoma.
     o Blood glucose alone is diagnostic for insulinoma, no other parameters need to be taken into consideration.
     o Repeated levels above 350 mg/dl might indicate diabetes mellitus. Which is rare in my experience.
          • It can also develop after a partial pancreactomy was performed.

Liver

  • ALT (Alanine Aminotransferase):

     o Liver specific in ferrets (not in rabbits!) is released when liver cells are damaged. Activity in liver is 3-10 higher than in other tissues (in ferret).
     o Normal value 80-290 IU/L
     o High normal value than in other species
     o Steriods can increase ALT very fast.
     o Hepatic lipidosis, lymphocytic hepatitis, other forms of hepatitis often produce:
          • up to 800 mg/dl
          • with Alk. Phos. up to 100 mg/dl
          • Increase in AST as well
               • Same occurs in gastritis
     o Careful when diagnosing primary liver disease on blood work alone.
          • Check for increased billirubin, low total protein and icterus
          • Suggest biopsy in order to characterize liver lesion.
               • Lymphocytic hepatitis
               • Suppurative hepatitis
               • Vacuolar hepathopathy
               • Hepatic lipidosis
               • Cirrhosis
               • Hepatic neoplasia
               • Billiary cystadenoma

  • GGT:

     o The biliary system is the primary source of plasma GGT. In addition to biliary GGT, significant levels of renal epithelial GGT can be found in the urine.
     o Normal around 5 IU/L
     o Over 10 IU/L high index of suspicion for liver problems.
          • Need to differentiate nature of elevation
          • Recommend abdominal ultrasound +/- US guided biopsy of liver to rule out primary liver pathology
          • Liver involvement is sometimes secondary to ascending inflammation from gut.
               • Suggest exploratory with multiple biopsies (GI tract, liver, lymphnode)