[Methodological aspects for the determination of the coagulative activity of coagulation factors II, V, VII and X from dog plasma].

For optimization of single factor II, V, VII and X activity measurements in dogs, dilution series of dog pool plasma were prepared using different commercially available calcium thromboplastins and deficient plasmas. Measured by use of a canine reference curve, the single factor activity in humans was 89% (factor II), 13% (factor V), 27% (factor VII) and 84% (factor X). Because the factor V and VII activity in dogs is much higher than in humans, in measurements using human-deficient plasma, a high sample predilution of at least 1:40 seems to be of advantage. Otherwise extreme variations of the factor V and VII activity may also influence the results of the other single factors. For determination of factor II, V and X activity, therefore, a non-standardized human placenta thromboplastin was especially suitable. With this reagent, the results were also reproducible at high sample dilutions (1:80, factor II and X; 1:160, factor V). Because of the low sensitivity of non-standardized human placenta thromboplastin to factor VII, measurements of this factor at a sample dilution of 1:40 required a standardized human placenta, or rabbit brain thromboplastin had to be used. For factor II measurements, the selection of a suitable deficient plasma is particularly important. Here, the reference curve showed a clear dependence on the commercial preparation chosen.