Pneumonia in calves

摘要

Currently unknown and non-culturable bacterial species may be involved in calf pneumonia. Teagasc researchers used a novel molecular diagnostic assay to identify bacteria, including non-culturable bacteria, which were present in the lungs and lymph nodes of calves that died from pneumonia.Morbidity and mortality (5.3%) rates in Irish calves are high. In the Republic of Ireland, 6.5%, equivalent to circa 132,297 calves, excluding stillborns, die in their first year of life. Pneumonia is the most common cause of morbidity and mortality in pre-weaned calves. It is a disease of the lower respiratory tract that causes the following symptoms: an elevated rectal temperature, an increased respiratory rate, nasal and ocular discharges, coughing, dyspnoea, a decreased appetite and depression (seeFigure 1). Pneumonia is normally contracted by calves following periods of stress and/or inhalation of primary pathogens, including viruses such as bovine herpesvirus-1 (also known as infectious bovine rhinotracheitis), bovine respiratory syncytial virus, bovine parainfluenza-3, bovine viral diarrhoea virus, bovine coronavirus, and Mycoplasma. They compromise lung function and allow colonisation by secondary bacterial pathogens, many of which are normal flora of the bovine upper respiratory tract, which are generally responsible for the progression of the disease and the ultimate death of the animal.