Agreement of manual cell counts and automated counts of the scil Vet abc Plus+ hematology analyzer for analysis of equine synovial fluid

•The scil Vet abc Plus+ is highly accurate to quantify NBCs in equine synovial fluid.•This analyzer is not accurate to differentiate NBCs in equine synovial fluid.•Hyaluronidase pretreatment did not improve accuracy of the scil Vet abc Plus+.

The purpose of this study was to determine whether the scil Vet abc Plus+ (SCIL Animal Care Company, Altorf, France), an impedance hematology analyzer, can accurately quantify and differentiate nucleated blood cells (NBCs) in equine synovial fluid. Synovial fluid samples (n = 242) in different stages of experimentally induced inflammation were analyzed with and without hyaluronidase pretreatment and compared to manual hemocytometer counts and smear reviews. No significant effect of hyaluronidase pretreatment was observed. Total nucleated cell counts of the scil Vet abc Plus+ were significantly higher compared to the manual method (P = 0.02), yet the difference was small and clinically irrelevant (ratio manual/automated count equal to 0.97 with 95% CI [0.95, 1.00]). Differential cell counts of the scil Vet abc Plus+ were not accurate. In conclusion, the scil Vet abc Plus+ hematology analyzer is highly accurate for quantification, but not accurate for differentiation of NBCs in equine synovial fluid.