title: Sensitivity of different prothrombin time assays to factor VII deficiency in canine plasma.
abstract: The factor VII sensitivity of prothrombin time (PT) in dogs was tested using five different PT reagents and a commercial PT variant. The five PT reagents were used according to manufacturers' instructions (standard test, PT([ST])) and also using a modified test instruction (modified test, PT([MT])). Plasma samples with defined factor VII levels (10-100%) were prepared by adding increasing quantities of canine factor VII deficient plasma to the pooled plasma of healthy dogs. Statistical comparison based on prothrombin time ratios (PTR = PT sample: PT measured for 100% factor VII activity level) revealed significant differences between different reagents for PT([ST]) and also for PT([MT]). Factor VII activity at which PT was prolonged to the upper limit of the reference values (FVII([X(0.975)])) was 16-39% (PT([ST])) and 23-35% (PT([MT])). Factor VII sensitivity measured by PTR and also by FVII([X(0.975)]) values, was higher in four of five PT reagents using PT([MT]) when compared with PT([ST]). The results of this study indicate the importance of selecting a sensitive reagent and method for PT measurement and for careful interpretation of PT test results using canine plasma.
authors.affiliation: Clinic for Small Animals, School of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173, Hannover, Germany. reinhard.mischke@tiho-hannover.de
authors.forename: R
authors.initials: R
authors.lastname: Mischke
authors.forename: M
authors.initials: M
authors.lastname: Diedrich
authors.forename: I
authors.initials: I
authors.lastname: Nolte
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000502:physiology*; D004283:Dog Diseases / Q000175:diagnosis* / Q000503:physiopathology; D004285:Dogs; D005168:Factor VII Deficiency / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D007202:Indicators and Reagents / Q000592:standards; D008297:Male; D011517:Prothrombin Time / Q000662:veterinary*; D012680:Sensitivity and Specificity
chemical_list: D007202:Indicators and Reagents