[Measuring fibrinogen concentrations in healthy dogs: standardization, comparison of methods and reference values]

Plasma fibrinogen concentration was measured in 67 healthy, adult dogs using five different methods (gravimetry, methods described by JACOBSSON (1955) RATNOFF and MENZIE (1951), and CLAUSS (1957), and functional photometric assay). Apart from using linear regression and the Pearson correlation coefficient (r) in order to characterize the relation between different methods, reference ranges (2.5-97.5%-fractile) were calculated for all methods. For calibration of the CLAUSS method (1957) and the photometric assay, dog plasma with a defined fibrinogen concentration was used. Measurements of commercial human fibrinogen standards yielded a good conformity with the concentrations specified by the manufacturer (values approximately 3% too low). These standards appear, therefore, to be also suited to the calibration of measurements of dog fibrinogen. The reference range for the gravimetry was 1.08-2.88 g fibrinogen per litre of plasma. A considerable conformity and close correlation was seen between the fibrinogen concentration measured by gravimetry and by using methods described by JACOBSSON (1955; y = 1.088 x -0.142, r = 0.967) or CLAUSS (1957; y = 0.999 x -0.004, r = 0.973), respectively. Between the reference-method gravimetry and the photometric method and RATNOFF-MENZIE (1951) method, respectively, a less close correlation, as well as a minor conformity, was found.