Early detection of bovine respiratory disease in calves by induced cough

Abstract

100 Holstein calves aged 7-14 days investigated the effectiveness of various cough provocation methods for bovine respiratory disease early detection. The animals were evaluated according to the clinical scoring system WI, to provoke cough in calves, they performed: 15-minute run, 30-second apnea on exhalation, palpated the trachea in its lower third region and intravenously injected 0.6% hydrogen peroxide solution at 0.9 % sodium chloride solution at a dose of 0.4 ml per kg of body weight to induce H2O2-induced bronchoconstriction. Out of 100 calves, 60 were selected without spontaneous cough and with a WI clinical score of 3 points or less, in which the leukocyte count, differential leukocyte count, neutrophil-to-lymphocyte ratio, nuclear shift index, and pH of exhaled breath condensate and the hydrogen peroxide concentration in exhaled breath. For 2 weeks, these animals were monitored daily for the bovine respiratory disease signs. It was established that 30-second apnea and H2O2-induced bronchoconstriction allow diagnosing bronchitis in calves 6-12 days before its symptom complex (peak) development when other symptoms are still absent and WI clinical score is 3 points or less. However, already at this disease stage, animals exhibit leukocytosis, increased serum content of haptoglobin, decreased pH exhaled breath condensate, and increased the hydrogen peroxide concentration in exhaled breath. The trachea lower third cough on palpation appearance indicates the tracheobronchitis early manifestations presence in calves. Trachea lower third Sequential palpation and 30-second apnoea to provoke coughing in calves allows not only the bovine respiratory disease early detection, but also to differentiate early bronchitis and tracheobronchitis manifestations.