Mycoplasmal diseases remain among the most intractable infectious diseases of cattle. Difficulties in diagnosis, poor response to treatment, few preventive measures and increased incidence have converted these diseases into a new frontier for the bovine practitioner. On this frontier, unknown factors and scarce resources create conditions of great danger, and perhaps also opportunity. A regional context is in order. In Asia, Africa, the Middle East, and parts of southwestern Europe contagious bovine pleuropneumonia, caused by Mycoplasma mycoides subsp. mycoides continues to be a problem. Rapidly spreading into new regions, or to regions previously cleared of this disease, the disease represents a continuing world-wide threat.8 Introductions of this endemic disease into North America via infected bovidae have been prevented by prolonged quarantine observations.
In the United States several diseases of bovines that are caused by mycoplasmas can be recognized. Feedlot pneumonia, arthritis, and mycoplasmal mastitis are diseases that can cause severe losses at this time. Pneumonia, arthritis and otitis of young diary calves can also be significant. Some mycoplasmas can play a significant role in enzootic pneumonia of dairy or beef calves. Finally, some diseases of minor importance have been recognized, such as ulcerative vulvovaginitis, ureaplasmal infertility and bovine mycoplasmal conjunctivitis. This paper will only provide an overview of the major bovine mycoplasmal diseases of North America.