Feline platelet counting with prostaglandin E1 on the Sysmex XT-2000iV

The large size of many feline platelets and the high frequency of platelet aggregation often results in falsely low platelet counts in this species. A combination of optical platelet counting to detect even large platelets and the use of prostaglandin E1 (PGE1) to inhibit platelet clumping may increase the accuracy of feline platelet counting.

The objective of this study was to compare platelet counts in feline whole blood samples with and without the addition of PGE1 and using different analytical methods in a clinical setting.

Platelet counts were determined in 10 feline patients in a referral veterinary hospital using 2 sample types (EDTA, EDTA with PGE1) and 2 methods of analysis (optical counting [PLT-O] and impedance counting [PLT-I]) on the Sysmex XT 2000 iV analyzer.

All PGE1-PLT-O samples had platelet counts of >200 x 10(9)/L. Mean platelet count using PGE1-PLT-O (410,256+/-178 x 10(9)/L) was significantly higher (P<.03) compared with PGE1-PLT-I (256+/-113 x 10(9)/L), EDTA-PLT-O (238+/-107 x 10(9)/L), and EDTA-PLT-I (142+/-84 x 10(9)/L) methods. Depending on the method, platelet counts in 2 to 7 of 10 cats were <200 x 10(9)/L when PGE1-PLT-O was not used. A slightly increased platelet count in response to treatment of a feline patient with thrombocytopenia would have been missed without use of PGE1-PLT-O.

Using PLT-O analysis on EDTA samples containing PGE1 provides higher, and therefore likely more accurate, feline platelet counts in a clinical setting.