Optimization of coagulometric tests that incorporate human plasma for determination of coagulation factor activities in canine plasma

Objective-To optimize methods used to measure coagulation factor activities in canine plasma, define reference ranges in dogs, and compare activities between canine and human plasma. Sample Population-Human plasma samples (n = 5) and plasma from healthy dogs (140) and dogs with low factor V activity (7), high factor V activity (7), and low factor VIII:C activity (6). Procedure-Coagulometric tests incorporated human plasma deficient in a single coagulation factor (human deficient plasma). Standard curves were generated with pooled plasma from 100 healthy dogs. Effect of sample dilution was evaluated, using plasma from dogs with high or low factor V activity and low factor VIII,C activity. Reference ranges for healthy dogs were established. Activities in human plasma were determined by comparison with standard curves obtained with canine plasma, Results-Activities of factors V and VIII:C in samples diluted less than or equal to1:20 influenced results of tests for other coagulation factors. Activities of factors V and VIII:C in human plasma were significantly less than in canine plasma. For the other coagulation factors, significant differences in human plasma-to-canine plasma activity ratios were detected among different sample dilutions. Conclusions and Clinical Relevance-Accurate measurement of coagulation factor activities in canine plasma, using human deficient plasma, requires higher sample dilutions (ie, > 1:20) than typically used for human plasma. Differences in activities between human and canine plasma and nonparallelism of the standard curves emphasize the necessity for use of species-specific standard curves for accurate determination of coagulation factor activity.