© 2014 American Society for Veterinary Clinical Pathology. Background: Platelet (PLT) concentrates (PC) can be produced via the buffy coat (BC) or platelet-rich plasma (PRP) protocols. The 2 methods have not been compared with canine blood. Objectives: The aims of the study were to compare the PLT, WBC, and RBC concentrations, in vitro PLT function, and markers of platelet storage lesion (PSL) in canine PC generated by 2 different protocols, and determine microbial growth throughout storage. Methods: PC from 8 healthy donor dogs were produced using 2 standard protocols, PRP and BC. PLT, WBC, and RBC counts, optical aggregometry assays, and PSL markers (pH, pCO2, HCO3, lactate and glucose concentrations, and LDH activity) were determined on storage days 0, 1, 3, 5, and 7. Aerobic and anaerobic bacterial cultures were also performed. Results: Mean PLT counts were comparable between protocols and remained stable throughout storage up to day 7, while median WBC and RBC counts on day 0 were significantly higher in the BC-PC group (17,800 WBCs/μL; 195,000 RBCs/μL) than in the PRP-PC group (200 WBCs/μL; 10,000 RBCs/μL) (P = .012). In PRP-PC aggregometry, the median slope and amplitude in response to γ-thrombin and convulxin (+ ADP) were significantly decreased, and virtually absent in BC-PC during storage. PSL markers (lactate, LDH activity) were higher in BC-PC. Aerobic bacterial growth was observed in 2 PRP-PC and 1 BC-PC. Conclusions: This in vitro study suggests that PRP-PC had lesser WBC and RBC contamination and superior PLT function compared with BC-PC. In vivo studies are required to address safety and efficacy of PRP-PC.