Evaluation of platelet function in dogs with cardiac disease using the PFA-100 platelet function analyzer

Background Cardiac disease has the potential to alter platelet function in dogs. Evaluation of platelet function using the PFA-100 analyzer in dogs of multiple breeds and with a broad range of cardiac conditions would help clarify the effect of cardiac disease on platelets. Objectives The objective of this study was to assess differences in closure time (CT) in dogs with cardiac disease associated with murmurs, when compared with that of healthy dogs. Methods Thirty-nine dogs with cardiac murmurs and turbulent blood flow as determined echocardiographically were included in the study. The dogs represented 23 different breeds. Dogs with murmurs were further divided into those with atrioventricular valvular insufficiency (n=23) and subaortic stenosis (n=9). Fifty-eight clinically healthy dogs were used as controls. CTs were determined in duplicate on a PFA-100 analyzer using collagen/ADP cartridges. Results Compared with CTs in the control group (mean +/- SD, 57.6 +/- 5.9 seconds; median, 56.5 seconds; reference interval, 48.0-77.0 seconds), dogs with valvular insufficiency (mean +/- SD, 81.9 +/- 26.3 seconds; median, 78.0 seconds; range, 52.5-187 seconds), subaortic stenosis (71.4 +/- 16.5 seconds; median, 66.0 seconds; range, 51.5-95.0 seconds), and all dogs with murmurs combined (79.6 +/- 24.1 seconds; median, 74.0 seconds; range, 48.0-187 seconds) had significantly prolonged CTs (P <.01). Conclusions The PFA-100 analyzer is useful in detecting platelet function defects in dogs with cardiac murmurs, most notably those caused by mitral and/or tricuspid valvular insufficiency or subaortic stenosis. The form of turbulent blood flow does not appear to be an important factor in platelet hypofunction in these forms of cardiac disease.