Evaluation of Time and Temperature Storage Effects on Canine Blood Anticoagulated with Citrate-Phosphate-Dextrose-Adenine Supplemented with Ethylenediaminetetraacetic Acid: Investigation of Optimal Conditions for External Quality Assessment Samples

External quality assessment (EQA) using fresh blood from companion animals has not yet been conducted worldwide. This study investigated storage temperature, duration, and anticoagulant conditions to identify more stable sample preparation methods for fresh canine blood stored for more than 24 h, as required for distributed surveys. Blood samples from five healthy dogs containing CPDA-1 supplemented with EDTA-2K at final concentrations of 1, 2, and 3 mg/mL were stored at room temperature (RT group) and refrigerated temperature (RE group). Complete blood count measurements were performed at 2, 5, 8, 24, 48, and 72 h after blood collection using the Microsemi LC-662, a point-of-care testing (POCT) automated hematology analyzer. White blood cell and platelet counts were more stable over time in the RT group compared with the RE group. In contrast, red blood cell parameters were more stable in the RE group. Variability in measured values increased with storage time but decreased with higher EDTA-2K concentration (3 mg/mL). Anticoagulation using CPDA-1 supplemented with EDTA-2K may be appropriate for future EQA programs using fresh canine blood.