Cytological Evaluation of Bone Marrow in Normal Laying Hens and those With Lymphoid Leukosis

The purpose of this study was to evaluate cytologically the bone marrow (and peripheral blood) of adult laying hens affected with lymphoid leukosis. Diagnosis of the neoplasm was made on the basis of clinical history, signs and symptoms and pathology. Only histologically confirmed cases were included in the study. Examination of blood smears revealed +2 heterophil toxicity and the presence of large numbers of reactive (blast – transformed) lymphocytes. Smears that were prepared from the bone marrow showed increased numbers of hemopoietic cells. The total erythrocyte count (TEC), hemoglobin percentage (Hb%) , hemoglobin concentration (Hb conc.), packed cell volume (PCV) and the mean corpuscular hemoglobin concentration (MCHC) values were significantly higher (P<0.01) in hens with lymphoid leukosis than in apparently normal hens. The mean corpuscular volume (MCV) and the mean corpuscular hemoglobin (MCH) were significantly lower (P< 0.01) in hens with lymphoid leukosis than in apparently normal hens. Results of the leukogram indicated that the total leukocyte count (TLC) and the percentage (%) of lymphocytes were significantly higher (P < 0.01) in hens with lymphoid leukosis than in apparently normal hens. From results of this study it was concluded that cytological evaluation of bone marrow may prove to be a simple , rapid , and useful tool in the diagnosis of lymphoid leukosis in laying hens.