Relationship of the extent of pulmonary lesions to the partial pressure of oxygen and the lactate concentration in arterial blood in calves experimentally infected with bovine respiratory syncytial virus.

Bovine respiratory syncytial virus (BRSV) is a primary agent of pneumonia in calves that causes damage to pulmonary epithelium and results in respiratory distress. This retrospective cumulative analysis of data from 681 calves experimentally infected with BRSV was undertaken to determine if there was an association of both the partial pressure of oxygen in arterial blood (PaO₂) and the lactate concentration in arterial blood with lung lesion severity, as well as to estimate the potential predictive value of these 2 parameters in assessing disease progression. The PaO₂ was highly significantly associated with the extent of lung lesions and was considered highly predictive of lesion severity. Although the arterial blood lactate concentration was also significantly associated with lung disease, the results were not consistent for all days after challenge. Also, the lactate level was usually within the reference interval. Thus, the usefulness of the arterial blood lactate concentration in predicting the course of BRSV-associated pneumonia is limited in the clinical setting.