[Mycoplasma bovis arthritis in a herd of dairy cattle]

Cases of severe arthritis due to M. bovis in a herd of dairy cattle are reported. M. bovis was also isolated from the mammary tissues and lungs of one of the lame animals at autopsy; this animal did not show any symptoms of respiratory disease or mastitis. M. bovis was detected in milk samples of eight animals in which mastitis was present or absent, though not in any of the animals affected with arthritis. Antibiotic therapy failed to produce permanent results in the lame animals. Ultimately, spontaneous recovery occurred in these cases. M. bovis was no longer isolated following the short period during which lameness was present.