Clinical and Clinicopathological Findings on Bovine Leukosis

II. Morphological Findings on Blood, Bone Marrow and Lymph Nodes Biopsied

Abstract

Biopsy was performed on 62 leukotic cows (10 for the calf, 18 for the thymic, 3 for the skin, and 31 for the adult types). The erythrocyte count was below 5.0×10⁶/μl in 80%, 38.9%, 33.3%, and 54.8% of the animals of the calf, the thymic, the skin, and the adult types, respectively.
On the basis of total leukocyte and absolute lymphocyte counts, the 62 cows were divided into three, group I of normal range, group II of range higher than normal, and group III of continuous leukocytosis or lymphocytosis. In leukocyte counts, groups II and III consisted of 70%, 77.8%, 66.7%, and 54.8% of the calf, the thymic, the skin, and the adult types, respectively. In absolute lymphocyte counts, groups II and III consisted of 50% of the calf, 55.6% of the thymic, 33.3% of the skin, and 71% of the adult types. Group III was composed of 40%, 44.4%, 0%, and 45.2% of the calf, the thymic, the skin, and the adult types, respectively.
An abnormal lymphocyte rate of 6% or more was seen in all the cases of the calf and skin types, and in 77.8% of the thymic and 96.8% of the adult types.
An increase in lymphocyte rate of 31% or more in bone marrow was found in 85.7% of the calf, 71.4% of the thymic, 33.3% of the skin, and 36% of the adult types. Further, most lymphocytes were always abnormal. In the superficial lymph nodes biopsied, proliferation of immature lymphocytes was observed in 90%, 88.9%, 100%, 100% of the calf, the thymic, the skin, and the adult types, respectively.