Individual reactivity of granulocytic system of newborn calves and its role in pathogenesis of inflammatory diseases of respiratory and gastrointestinal tracts

Inflammatory diseases of the respiratory and gastrointestinal tracts are the actual problem of veterinary medicine. Innate or natural immunity plays the leading role in the initial reactions to microbial agents contaminating sterile mucous membranes of newborn animals. It is implemented through the activation of cellular and humoral factors of nonspecific resistance. Leukocyte concentration, leukogram, content of cationic proteins in neutrophils, blood serum lysozyme activity (BSLA) were studied in 20 red-motley calves in 1 hour after their birth on the days 2, 5-7 and 14-15 of life, together with an impact of these indices on the terms of appearance and clinical course of inflammatory diseases of the respiratory and gastrointestinal tracts, under conditions of a large dairy complex environment (Voronezhpischeprodukt Co Ltd, Novousmansky district, Voronezh region) in 2014. Blood sampling was implemented in the morning before feeding from the jugular vein. Body temperature, pulse and respiratory rate, state of the visible mucous membranes, time of appearance and intensity of sucking reflex, the presence and nature of cough, dyspnea, nasal expiration, reaction to palpation of the larynx, trachea, intercostal spaces, the abdominal wall, percussion and auscultation of the chest were determined in calves. The markers of intestinal inflammation are soluble protein, erythrocytes (hemoglobin), leukocytes (leukocyte elastase), pH. They were identified in feces by dry-chemistry method during the same period and also selectively at the age of 1-1.5 months. According to clinical and hematological indices the animals were retrospectively divided into 2 groups: group A with leukocyte concentration of (11.0-18.3)½10 9/l and segmentonuclear neutrophils (SN) more than 4½10 9/L at birth; group B with leukocyte concentration of 6.5-11.3½10 9/l and SN lesser than 3.9½10 9/l at birth. Granulocyte blood concentration dynamics in calves of these groups significantly differed both among themselves and from physiological dynamics (adaptive norm) during the first 15 days of their life. This was determined by various phases of adaptation syndrome (mobilization, resistance, exhaustion) and various possibilities of calves’ granulocytic system reaction to irritants impact according to J. Wilder’s law of initial values (1957). The increased blood level of SN and rod neutrophils (RN) in animals of group A at birth indicates existing activation of bone marrow and may not significantly increase in response to a rather intensive stimulus. Initial level of SN and RN in calves of group B was close to the physiological one, it significantly increased on the day 2 and decreased by the days 5-7 of life. Cationic protein concentration and BSLA in all the calves during the research period were lower than the indices typical of the animals of this age. Diarrhea developed in all the calves on the day 2 of life. Its duration in animals of groups A and B was 8.6±1.1 and 4.2±0.6 days, respectively. When diarrhea symptoms disappeared, intestinal inflammation markers were identified in calves’ feces during 1-1.5 months. During the first 14 days of life the first bronchitis symptoms (induced cough) were registered in all the animals. The course of the disease was light in most of the calves. The mechanisms of changes of granulocytic system reactivity, leading to its decompensation and respiratory tract inflammation development, are discussed.