Cellulose acetate electrophoresis of canine plasma after fibrinogen precipitation by ethanol.

BACKGROUND: In routine canine medicine, anticoagulated blood is often the only sample sent to laboratories for diagnostic purposes. This hampers the interpretation of protein electrophoretic tracings because plasma contains fibrinogen, which migrates in the beta-gamma region. In human medicine, fibrinogen can be precipitated from plasma using ethanol. OBJECTIVES: The purpose of this study was to assess ethanol precipitation as a method for removing fibrinogen from canine plasma so as to facilitate the interpretation of electorphoresis results. METHODS: Blood samples collected from 40 dogs were divided into plain tubes and tubes containing EDTA (n=20) or lithium-heparin (n=20). An aliquot of plasma from each sample was incubated with ethanol at a final concentration of 100 mL/L. Cellulose acetate electrophoresis was then performed on serum, plasma, and plasma treated with ethanol. To verify the efficiency of ethanol treatment, fibrinogen was added to 5 canine serum samples at final concentrations of 2.5, 5.0, and 10.0 g/L, and electrophoresis was performed before and after ethanol treatment. RESULTS: Visual analysis of electrophoretograms from ethanol-treated samples confirmed the disappearance of the fibrinogen peak from the beta(2)-globulin region. Treatment with ethanol caused a significant decrease in the percentage of beta(2)-globulins and a significant increase in the percentage of alpha(2)-globulins. Absolute values of most electrophoretic fractions were significantly decreased in ethanol-treated plasma compared with serum. CONCLUSIONS: Ethanol treatment successfully removed fibrinogen from canine plasma and normalized electrophoretic profiles, but probably also precipitated proteins other than fibrinogen. Ethanol treatment is recommended to facilitate visual identification of abnormal monoclonal peaks, but not for determining absolute protein concentrations in electrophoretic fractions