Informative value of blood l-lactate and integral leukocyte indices for predicting severe course of mycoplasmosis in calves

Abstract

The aim was to study the informativity of blood L-lactate and integral leukocyte indices for predicting a severe course of mycoplasmosis in calves during their natural infection with M. bovis. Daily clinical observation of 36 Holstein calves naturally infected with M. bovis (at the age of 10-15 days) was carried out for one month on the farms of the Ural Federal District. In blood samples obtained from the jugular vein of animals at the first signs of the disease, the levels of hemoglobin, erythrocytes, leukocytes, platelets, hematocrit on Abacus Junior Vet analyzer (Diatron, Austria), L-lactate concentration - by reaction with paraoxydiphenyl on UV-1800 spectrophotometer (Shimadzu, Japan) were studied. Differential leukocyte counts in Romanowsky- Giemsa stained blood smears were performed using Olympus BX43 microscope (Olympus, Japan). The following integral leukocyte indices were calculated: Krebs index (KI), leukocyte index of intoxication by Y. J. Calf- Calif (LII), neutrophil reactive response by T. Sh. Khabirov (NRR), adaptation index (AI), Bredeck index (IB), nuclear shift index (NSI), lymphocyte- granulocyte index (ILG), neutrophil to monocyte ratio index (NMR), leukocyte shift index (LSI), lymphocyte to monocyte ratio index (LMR) and lymphocyte to neutrophil ratio (LNR). In 22 (61,1 %) calves a mild to moderately severe course was detected, in 14 (38,9 %) - a severe course of mycoplasmosis. The animals predisposed to a severe course of mycoplasmosis had higher blood L-lactate > 1.68 mmol/l, AI > 1.57 units, ILG > 16.7 units, LNR > 1.41 units, reduced KI < 0.645 units and LSI < 0.600 units at the first clinical signs of disease. The information value of predictors for prognosing severe mycoplasmosis in calves was evaluated as very good; the sensitivity was 71.4-85.7 %, the specificity made 81.8-90.9 %. The accumulation of L-lactate in the blood of animals and changes in leukocyte indices (AI, ILG, LNR, KI, LSI) were shown to be interrelated.