Mycoplasma Bovis is one of 13 Mycoplasma species known to infect cattle. Most of these Mycoplasma species do not cause disease, but M. bovis is considered an important pathogen for cattle. The defense mechanisms that organisms have are:
In a 2006 study, the pathogen Mycoplasma Bovis was found in 46 percent of cattle with normal lungs (Gagea et al. 2006), 85 percent of cattle with acute fibrinous pneumonia, and 98 percent of cattle with chronic pneumonia . (Gagea, et al., 2006) Most cases of Mycoplasma Bovis are resistant to antibiotics and difficult to treat .
Mycoplasma Bovis appears when the initial stressor causes calves to develop traditional Bovine Respiratory Disease Complex (BRDC or transport fever) and Mycoplasmosis develops 7 to 14 days later. Mycoplasma weakens the immune system of cattle and prevents the respiratory tract from defending itself against diseases (Smith, 2002, p 559). Common clinical signs are a harsh dry cough, low-grade fever, slightly increased respiratory rate, mild depression, and runny eyes. Mycoplasma Bovis is often suspected when cattle with pneumonia do not respond to treatment.
Outbreaks of mastitis in flocks are severe and sometimes co-occur with arthritis. Mycoplasma Bovis is considered an infectious mastitis pathogen that spreads during the milking process and the response to treatment is very poor. Udder infection causes a decrease in milking efficiency.
Calves with pneumonia due to M. bovis develop severe arthritis after two to four weeks. Different strains of M. bovis have different chances of causing joint problems, so some outbreaks have too many lame calves and others none.
Mycoplasma Bovis causes severe arthritis in calves and rarely diagnosed adult cattle. Rapid damage occurs to one or more swollen lower extremity joints.
In adults, this form of the disease can occur on its own or in combination with mastitis. Antibiotic treatment in the early stages of the disease provides the most appropriate opportunity to control the disease.
This clinical finding is most common in young animals, especially in young dairy calves presenting with drooping ears or head tilt. Veterinarians have reported that this finding has increased over the past 10 years. (DEFRA October 2018 UK Beef Expert Group)