Diagnosis is one of exclusion.
Complete blood work should be performed, including CBC, serum biochemistry, bile acids, lead, and zinc levels, and protein electrophoresis. Phenobarbital levels should be evaluated twice yearly and compared with therapeutic levels from mammals. The author has had successful outcome with serum Phenobarbital levels less than that of the therapeutic range fro mammals. Veterinary News, Penn State Cooperative Extension, March 2001.