Assessment of a platelet function analyser in horses: Reference range and influence of a platelet aggregation inhibitor

The objective of this study was to assess whether a new human platelet function analyser (the PFA-100) could be used to evaluate platelet function in horses and detect acetylsalicylic acid (ASA)-induced platelet dysfunctions. Citrated blood samples from 40 healthy horses were processed to obtain reference values for closure time (CT) using cartridges with collagen–ADP (CT–ADP) and collagen–epinephrine (CT–EPI) as platelet agonists. In addition, CT–ADP and CT–EPI were also measured before and 24 h after oral ASA administration in another 12 healthy horses. The sensitivity and specificity of the test were also determined. mal horses, means ± SD value for CT–ADP was 85.1 ± 13.1 s (median, 82 s), and CT–EPI ranged from 158 to >300 s (median 291 s). Calculated reference ranges were 60.5–115.9 s and 158.5–>300 s for CT–ADP and CT–EPI, respectively. Administration of ASA significantly (P < 0.001) prolonged CT–ADP values from 91.0 ± 13 to 113.5 ± 14.4 s, and CT–EPI values were also significantly (P < 0.008) prolonged after ASA administration. Sensitivity and specificity results for ADP cartridges showed that a prolonged CT value would be highly suggestive of a platelet aggregation inhibition. In conclusion, ADP cartridges can be used in horses to assess primary haemostasis and may be a valuable test for the detection of platelet aggregation inhibition.