Comparative Analysis of Leukocyte Proportions and Morphology in Wild Muridae and Arvicolinae Rodents

Hematological profiles of wild rodents provide important insights into their species-specific adaptations, physiological status, and immune responses. However, reference data for wild species remain limited since these are mainly derived from laboratory rodents. This study investigated the leukocyte composition and morphology in 113 wild rodents representing the family Muridae and the subfamily Arvicolinae from several regions of seven prefectures of Greece. Blood samples were collected from live-trapped individuals, and peripheral blood smears were analyzed using Giemsa staining. We evaluated leukocyte variation related to taxonomy and sex. Marked differences were observed between Muridae and Arvicolinae, while lymphocytes predominated in both. Arvicolinae exhibited higher neutrophil and lower lymphocyte proportions than Muridae. Leukocyte profiles were relatively consistent among Arvicolinae, but interspecific variation was evident within the genus Apodemus. No statistically significant differences in leukocyte proportions were detected between males and females. Morphologically, reactive lymphocytes were observed in Muridae, while cells morphologically consistent with azurocytes were observed in Microtus thomasi and in the single examined individuals of M. felteni and M. subterraneus. The findings provide new comparative hematological data for wild rodents and highlight the importance of species-specific reference values in eco-immunological studies.