Effects of breed and sex on platelet and white blood cell counts in equine platelet-rich plasma and peripheral blood

Introduction: Platelet-rich plasma (PRP) is increasingly used in equine medicine, but its composition and therapeutic efficacy vary depending on preparation methods and intrinsic factors such as breed and sex. Aim: To evaluate the effects of breed and sex on platelet (PLT) and white blood cell (WBC) counts in peripheral blood and PRP of Thoroughbred (TB) and Purebred Arabian (PA) horses. Methods: Forty-one clinically healthy racehorses (23 TB, 18 PA; aged 3–6 years) were sampled. PRP was prepared using a three-step centrifugation protocol. PLT and WBC counts were measured with an automated hematology analyzer and confirmed microscopically. Data were analyzed using t-tests or Mann–Whitney U tests (p < 0.05). Results: Peripheral WBC counts were significantly higher in TB than PA horses (8.79 ± 1.28 vs. 7.60 ± 1.67 ×10³/µL; p = 0.013), while peripheral PLT counts did not differ by breed (p = 0.269). PRP PLT counts were significantly higher in TB compared to PA horses (845.77 ± 316.34 vs. 647.00 ± 213.84 ×10³/µL; p = 0.033). Regarding sex, no significant differences were found in peripheral WBC (p = 0.720) or PLT counts (p = 0.423). In PRP, WBC counts were significantly higher in males compared to females (52.97 ± 29.72 vs. 40.37 ± 20.05/µL; p = 0.039), while PRP PLT counts showed no sex-related difference (p = 0.445). Conclusion: Both breed and sex influence the cellular composition of equine PRP. Thoroughbreds yield higher PRP platelet concentrations than Arabians, and males exhibit higher PRP leukocyte levels than females. These intrinsic factors should be considered when interpreting hematological data and optimizing PRP-based regenerative therapies. Future studies with larger, multi-breed cohorts are warranted to refine standardization efforts.