Mycoplasma bovis is an important cause of chronic respiratory disease and arthritis in feedlot cattle and in young dairy and veal calves. Multiple species of mycoplasma can be isolated from the respiratory tract of non-pneumonic calves; however, the frequency of isolation is greater in those with respiratory tract disease.
M bovis has been associated with otitis media in young calves and a syndrome involving chronic pneumonia and polyarthritis in feedlot cattle and in young dairy and beef calves. These cattle invariably have chronic bronchopneumonia with caseous and coagulative necrosis, and 40%–60% may also develop a polyarthritis and tenosynovitis that causes severe chronic lameness. The condition results in a chronic disease that does not respond to antimicrobial treatment; many of these animals are euthanized as a result.
Culture of these organisms requires special media and conditions; growth of the organisms may take up to a week. PCR tests are now available and can detect the mycoplasma within hours, thus greatly speeding up diagnosis. Vaccines are commercially available for M bovis, but their efficacy has not been demonstrated.