Mycoplasma bovis-associated pneumonia and arthritis complicated with pyogranulomatous tenosynovitis in calves.

Immunohistochemistry and bacteriologic culturing were used to detect Mycoplasma bovis in tissue specimens from feedlot calves affected with pneumonia and arthritis. Two herds with 110 Charolais calves and 25 Angus calves were examined. Clinical signs included severe respiratory distress, anorexia, pyrexia, and lameness, which affected nearly a third of the calves. Lung lesions were characterized by numerous abscesses. Synovial lesions of the limbs included pyogranulomatous tenosynovitis, bursitis, and synovitis, particularly in the areas of the carpal and elbow joints. Abscesses in lung and synovial tissues contained accumulations of M bovis antigens, as revealed by immunohistochemistry. The findings of this report indicate that infection with M bovis may result in a pneumonia-arthritis syndrome with pyogranulomatous lesions in calves.