Informativeness of Blood L-Lactate and Integral Leukocyte Indices for Prediction of Severe Mycoplasmosis in Calves

Abstract

The study was carried out to assess the informativeness of blood L-lactate and integral leukocyte indices to predict severe mycoplasmosis in calves naturally infected with M. bovis. In the conditions of agricultural enterprises of the Ural Federal District, daily clinical observation of 36 Holstein calves naturally infected with M. bovis at the age of 10–15 days was carried out for 1 month. In blood samples obtained from the jugular vein of animals at the first signs of the disease, the content of hemoglobin, erythrocytes, leukocytes, platelets, and also hematocrit was determined on an Abacus Junior Vet analyzer (Diatron), the concentration of L-lactate was determined by reaction with paraoxy-diphenyl on a UV-1800 spectrophotometer (Shimadzu), a differential count of leukocytes in blood smears stained according to Romanovsky-Giemsa was performed on an Olympus BX43 microscope (Olympus, Japan), and the integral leukocyte indices, the Krebs’ index (KI), the leukocyte intoxication index of Ya.Ya. Kalf-Kalif (LII), reactive neutrophil response by T.Sh. Khabirov (RNR), adaptation index (AI), Bredeck’s index (BI), nuclear shift index (NSI), lymphocyte-granulocyte index (LGI), neutrophil-monocyte ratio index (NMR), index of blood leukocyte shift (BLSI), lymphocyte-monocyte ratio index (LMR), and lymphocyte-neutrophil ratio (LNR) were also calculated. A mild and moderate course of mycoplasmosis was established in 22 (61.1%) calves and a severe course in 14 (38.9%). In animals predisposed to a severe course of the disease, an increased level of L-lactate in the blood was recorded at the first clinical signs of the disease: > 1.68 mmol/l, AI > 1.57 units, LGI > 16.7 units, LNR > 1.41 units, reduced KI < 0.645 units, and BLSI < 0.600 units. The informativeness of predictors for prognosticating severe mycoplasmosis in calves was assessed as very good, sensitivity was 71.4–85.7% and specificity was 81.8–90.9%. The accumulation of L-lactate in the blood of animals and changes in leukocyte indices (AI, LGI, LNR, KI, BLSI) are interrelated.