APPLICABILITY OF THE ACTIVATED PARTIAL TH ROMBOPLASTIN TIME (APTT) ASA SCREENING-TEST OF MILD OR MEDIUM DEFICIENCIES OF COAGULATION-FACTORS IN CATS

The present investigation examined if the aPTT shows sufficient sensit ivity for single factor activities also in cats when measured with the test optimized for humans using a commercial reagent. Comparative mea surements were done with different modifications of the aPTT (sample p redilution, addition of fibrinogen). Measurements of the gPTT using di fferent methods and the activity of the coagulation factors Il, V, X, VIII, IX, XI, and XII were performed in 42 healthy cats in order to de termine the reference ranges. The same measurements were done on 21 ca t plasmas where at least one of the coagulation factors was diminished in relation to the corresponding reference range. The conventional aP TT reflected the decrease in coagulation factor activity in each of th e 21 plasmas by prolongation above the reference range (14.6-24.4 s). The test thus possesses high sensitivity and is a suitable screening t est also for the cat. In contrast, in tests with sample predilution th e sensitivity was lower (3-4 false negative results). This was probabl y caused by the distinct increase of the range of the reference values .