A beef herd presented four calves, aged 8–9 months, in late September for evaluation of respiratory disease of 2 months duration that was non-responsive to antimicrobial treatment. Calves were housed on a marshy pasture and similar signs occurred in calves during the same months the previous 2 years. The owner reported greater than 50% of calves were affected with a significantly decreased rate of gain. Physical examination revealed tachypnea and cough. Transtracheal wash cytology, viral respiratory PCR panel and bacterial culture were performed. The viral respiratory PCR panel was negative, and bacterial cultures identified commensal bacteria.