Mycoplasma bovis as an agent of mastitis, pneumonia, arthritis and genital disorders in cattle

Bovine diseases due to Mycoplasma bovis can cause considerable economic losses in cattle production. While the pathogen is principally responsible for therapy-resistant mastitis on large dairy farms, on smaller farms the typical mycoplasma diseases are calf pneumonia and arthritis. Moreover, the pathogen is able to cause genital disorders. M. bovis infection can be controlled effectively only if appropriate measures are implemented at the earliest possible stage. Since immunoprophylaxis and antibiotic treatment are known to be ineffective, control measures must include the introduction of strict hygiene standards, the restriction of animal movement out of infected herds and the culling of clinically diseased animals and shedders of the mycoplasma (the latter only in the case of mastitis and genital disorders). In this review, symptoms of the various diseases caused by M. bovis are described and characteristics of the course of infection are outlined. To clarify the origin and spread of the infection, the authors describe the main properties and reservoirs of the pathogen and summarise experimental evidence on modes of transmission to susceptible organs. As effective diagnosis is a prerequisite for the introduction of early control measures, the advantages and disadvantages of currently used diagnostic methods are discussed in detail. It is a serious shortcoming if testing for mycoplasmas is not included in routine bacterial examination of clinical samples. As a consequence, some M. bovis infections will remain undetected and outbreaks cannot be controlled properly. Finally, practical recommendations are given for prevention and control, including the formation of mycoplasma-free herds.