Assessment of platelet function in healthy sedated cats using three whole blood platelet function tests

Abstract

The objectives of this study were to establish feline references intervals for 3 commercial whole blood platelet function test analyzer systems: Multiplate analyzer (MP; Roche Diagnostics International Ltd., Rotkreuz, Switzerland), Platelet Function Analyzer-100 (PF: Siemens Canada, Mississauga, Ontario, Canada), and Plateletworks Combo-25 kit (PW; Helena Laboratories, Beaumont, TX). Venipuncture was performed on 55 healthy sedated cats, and platelet aggregation in response to adenosine diphosphate (ADP), collagen (COL), and arachidonic acid (AA; MP only) was assessed using citrated blood. For the MP analyzer, median (95% confidence intervals [CIs]) area under curve (Units) for ADP, COL, and AA agonists were 87 (11–176), 81 (32–129), and 91 (59–129), respectively. For the PF analyzer, median (95% CIs) closure time, using COL–ADP cartridges, was 69 (46–89) sec. For the PW assay, median (95% CIs) percent aggregations for ADP and COL agonists were 71 (18–92) and 49 (9–96), respectively, using impedance hematology analyzer platelet counts, and 94 (25–98) and 68 (14–119), respectively, using flow cytometry hematology analyzer platelet counts. There were low correlations between the PF analyzer (COL–ADP cartridge) and MP analyzer (COL agonist; ρ = 0.11), and between the PF analyzer (COL–ADP cartridge) and PW assay (COL agonist using impedance platelet counts; ρ = 0.14). The PW assay percent aggregations using impedance and flow cytometric platelet counts were correlated for both ADP (ρ = 0.64) and COL (ρ = 0.64) agonists. Platelet function testing using these tests are feasible in cats, but 95% CIs are wide, so single results may be difficult to interpret. Platelet counting by impedance or flow cytometry may be used for the PW assay but are not interchangeable.