Because changes in rat and dog hematological parameters according to storage conditions have been
poorly documented, we sought to examine such changes. Blood analysis was performed using two
hematology analyzers (ADVIA 2120i and Sysmex XN-V) after storage at room temperature and in cold
storage for 5, 24, and 48 h, respectively. Interassay coefficients of variation for hematological parameters
analyzed with the ADVIA 2120i and the XN-V showed similar. The levels of hematocrit, mean corpuscular
volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and platelet (PLT)
showed significant variations with time in blood samples of rats and dogs. The leukocyte subpopulation
showed high variation with storage conditions. The data for leukocyte differential counts obtained using
the ADVIA 2120i, XN-V, and a manual differential counting procedure showed good agreement for
neutrophils and lymphocyte counts, but monocytes, eosinophils, and basophils showed differences between
the procedures. In conclusions, most rat and dog hematological parameters showed minimal changes;
however, some showed high variation with storage time and temperature, especially PLT and leukocyte
subpopulations. In conclusion, when performing hematological analysis in dogs and rats, it will be
exactitude to analyze blood samples in fresh condition and at least within 24 h in the cold storage.