Prognosis of development and severity rate in case of cattle leucosis

There have been developed 3 methods to predict the course of leucosis in cattle of different age infected with LV according to the hematological investigation, there is given an estimation of severity of leucosis process (LP) according to the content of average molecular mass substances (AMMS) in blood plasma of healthy, BLV-infected and leucosis-diseased animals. The first method of predicting the leucosis course in BLV-infected animals comprises comparing the numbers of physiologically normal leucocytes and lymphocytes. Bringing the quantitative values closer to their upper limit of physiological standard speaks for increased risk of leucosis. The second method comprises a leucogram determining the ratio of lymphocytes and segmented neutrophils (SN) in leucosis-free animals. With their ratio of 1.2:4.8, after 18 months 66.7% of BLV-infected cows and 1.1% leucosis diseased cows in hematological stage were found; with 5.1:9.9 – 72% and 16%, respectively; with 10.8-98.0 – 71.4% leucosis-diseased in hematological stage. With the ratios of lymphocytes and SN being 1.2-4.8 the resistance was high; 5.0:9.9 – reduced and 10.8-9.9 – low. The third method of predicting comprises determining the percentage of SN in the leucogram in BLV-infected animals. The negative clinical course of no-symptom stage leucosis was predicted in animals with less than 20% of SN. An estimation of severity of leucosis process by the content of AMMS in blood plasma has shown the symptom-free stage of leucosis is diagnosed in BLV-infected animals with AMMS being 12.7 to 15.2 optical density units, hematological and increased severity of leucosis – with 19.0 and mo optical density re units. Thus, the method of predicting the course and severity of leucosis in cattle are simple, economical and recommended to use in veterinary laboratories as allow detecting in time and culling animals at symptom-free and hematological stages of leucosis to obtain good quality meat products