Summary
A flow cytometric platelet immunofluorescence assay (fc-pifa) was compared with a previously developed microscopic platelet immunofluorescence assay (mi-pifa) for detection of circulating platelet antibody. Both assays were performed on serum from 10 healthy dogs with normal platelet count, and on serum from 27 thrombocytopenic dogs—18 had primary immune-mediated thrombocytopenia (imt), and 9 had imt in addition to other immune-mediated disease (secondary imt). Both assays yielded negative results for all control dogs. The mi-pifa and fc-pifa results were in agreement in 23 dogs with imt (14 positive and 9 negative). There was linear correlation between mi-pifa scores and fc-pifa results (r = 0.873). Positive results were obtained for 55.5% of the dogs with suspected imt, using the mi-pifa, compared with 67%, using the fc-pifa; however, the difference was not statistically significant. Use of fresh or frozen fixed donor platelets as the antigen source yielded similar results in the fc-pifa.
