Outbreak of pneumonia and arthritis in beef calves associated with Mycoplasma bovis and Mycoplasma californicum

During an outbreak of pneumonia and arthritis in beef calves and young cattle on a large farm in north‐west Germany, Mycoplasma bovis and Mycoplasma californicum were isolated from tracheobronchial lavage fluids and synovial fluids. The microbiological findings in dead and living animals and the immunohistochemical demonstration of M californicum antigen in lung and arthritic joint tissue, indicated that under poor housing conditions and possibly other predisposing factors, this mycoplasma, like M bovis , can colonise the respiratory tract and may be able to cross the respiratory mucosal barrier to spread through an infected animal and cause systemic infections that may contribute to severe arthritis.