Blood Cell Morphology of Harbor Seals Phoca vitulina Linnaeus, 1758 from the Commander Islands

The blood cells of common (harbor) seals, Phoca vitulina L. 1758, from the Commander Islands population are characterized in detail for the first time. Data on composition, size and ratio of erythrocytes, leukocytes, and platelets in the peripheral blood of immature and mature seals are given. A micrograph library for all types of peripheral blood cells of harbor seal is presented. The blood cells morphology of this seal generally corresponds to that of other pinniped species; however, neutrophils with Dohle bodies, reactive lymphocytes, and hypersegmented neutrophils were found in blood smears. An increased number of eosinophils (10–25%) were observed in the leukocyte formula of all seals examined. Mature seals had higher numbers of eosinophils (p = 0.04) and large lymphocytes (p = 0.005); immature seals had higher numbers of monocytes (p = 0.04) and Howell–Jolly bodies in erythrocytes (p = 0.03). Microfilariae and nucleated erythrocytes were found in blood smears of two mature seals.