Bone marrow cell composition and morphology in healthy juvenile female New Zealand White rabbits (Oryctolagus cuniculus).

Abstract

OBJECTIVE To provide contemporary preliminary guidelines for the morphological evaluation of bone marrow in conjunction with CBC results for healthy juvenile (3- to 6-month-old) female New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS 22 female New Zealand White rabbits. PROCEDURES Each rabbit was sedated, and a blood sample (3 mL) was collected from an ear artery for a CBC, after which the rabbit was euthanized. Within 5 minutes after euthanasia, bone marrow samples were obtained from the femur for cytologic and histologic evaluation. Bone marrow specimens for cytologic evaluation were stained with modified Wright stain, and those for histologic evaluation were stained with either H&E or Prussian blue stain. RESULTS The CBC results were within published reference ranges for all rabbits except 4, each of which had mild leukopenia. Cytologic assessment of bone marrow revealed a median myeloid-to-erythroid ratio of 0.7 and 2.8 megakaryocytes/low-power field (magnification, 100X), and the median percentages of lymphocytes, plasma cells, and macrophages were 11.5%, 0.1%, and 0%, respectively. The myeloid-to-erythroid ratio was not significantly correlated with any CBC variable. On histologic evaluation of bone marrow, the cellularity ranged from 30% to 50%, there were 2.1 to 7.7 megakaryocytes/hpf (magnification, 400X), and no iron stores were visible in H&E or Prussian blue-stained specimens. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study provided contemporary preliminary guidelines for the evaluation of bone marrow in healthy laboratory rabbits.