Mycoplasma bovis

Mycoplasma bovis causes several diseases in cattle including respiratory disease and mastitis.

Mycoplasma bovis is a very small bacteria which infects cattle and can be difficult to treat. The organism has a number of its own defence mechanisms, which include:

• The lack of the cell wall so that certain widely used antibiotics are not effective
• An ability to change the surface proteins so it can evade the cow’s immune response
• An ability to produce a sugar matrix (biofilm) so that it can temporarily hide from both the immune system and antibiotic treatment

Mycoplasma bovis causes several diseases in cattle in GB.

The most common is respiratory disease in calves and, less commonly ear infections (otitis media) resulting in head tilt.

In older animals it can also cause arthritis, mastitis and pneumonia. Eye infections (infectious keratoconjunctivitis) and abortion have also been recorded

Although much material has been published in the UK, information on the internet from other countries requires caution when interpreting because the disease can manifest differently in the UK

Mycoplasma bovis does not cause disease in humans and it is not a notifiable disease.

Mycoplasma bovis is not related to Mycobacterium bovis (the pathogen which causes bovine tuberculosis). 

• Bovine Respiratory Disease (BRD) is a complex disease caused by a range of bacteria, viruses and other pathogens including

• It is the most common form of disease associated with Mycoplasma bovis

• Mycoplasma bovis can also be the sole cause of pneumonia in some outbreaks and is often suspected when cattle with pneumonia do not respond to treatment

Calves are most commonly affected, although Mycoplasma bovis can cause respiratory disease in all of ages of cattle.

Symptoms include:

• Lethargy
• Fever
• Nasal discharge
• Rapid and shallow breathing
• Coughing
• A head tilt due to ear infection or swollen joints (less common)

• Mycoplasma mastitis is a rarely diagnosed cause of mastitis in GB and of these, Mycoplasma bovis is the most frequently isolated cause; it responds poorly to antibiotic treatment
• Mycoplasma bovis behaves as a contagious mastitis pathogen, and spread at milking is the most likely means of transmission

• Mycoplasma bovis causes a rarely diagnosed severe arthritis in calves and adult cattle. Animals are very lame, with one or more swollen lower limb joints
• This form of the disease can occur by itself or with other signs such as respiratory disease or mastitis
• Effective antibiotic treatment in the early phase of the disease provides the best opportunity to control disease; discuss treatment options with your vet 

• The organism is usually transmitted by close contact – isolate sick animals
• Unpasteurised infected milk can be a source of infection to calves
• Transmission between cows is from contagious spread at milking but may also be via shedding of the pathogen from the eyes, nose, vagina and rectum, and through milk
• Cattle may be asymptomatic carriers of Mycoplasma bovis, their role in the disease is not clear, but make sure you are aware of this when buying in cattle
• In herds with concurrent disease issues, poor nutrition or environment, Mycoplasma outbreaks can be severe

There are several methods available to diagnose Mycoplasma bovis infections in cattle.

PCR and culture tests detect the organism and indicate active infection; culture tests may take up to 21 days to produce results.

Single serology tests (e.g. ELISA) detect antibodies and indicate exposure to Mycoplasma bovis in the herd.

Paired serology tests (two samples taken several weeks apart) detect increasing levels of antibodies, indicating active infection.

Different tissues can be sampled for diagnosis:

• Blood samples and nasopharyngeal swabs are suitable for testing individual animals
• Milk tests can be used to detect individual mastitis cases, while bulk tank tests can be used to screen and monitor for milking herd exposure to Mycoplasma bovis; successful bulk tank culture is reliant on a clean milking routine to minimise contamination with environmental organisms
• Other sample types may be recommended by your vet, for example bronchoalveolar lavage or joint fluid

The largest risk is considered to be from the purchase of cows or heifers, clinically or subclinically infected with Mycoplasma bovis. 

Maintaining a strictly closed herd policy is the best method to minimise the risk of introduction of Mycoplasma bovis.

If cows or heifers must be purchased, there is always a risk of buying in infection. This risk can be minimised by collecting a detailed history, only purchasing from low somatic cell count herds, and by serological screening of the herd from which animals have been purchased.

Individuals should be quarantined before they enter the main herd and can be tested for antibodies.

The practice of feeding whole milk to calves is not recommended in herds where Mycoplasma bovis has been diagnosed. To reduce the risk of transmitting infection to calves, whole milk should be pasteurised. Feeding calf milk replacer is a alternative option.

A licensed commercial vaccine is available. We recommend that you discuss this with your vet to decide whether vaccination against Mycoplasma bovis would be beneficial on your farm.

Historically vets could request autogenous vaccine development on a case-by-case basis, and from 2019 a vaccine could be imported from the USA on prescription through the cascade system. In 2025, a modified-live vaccine was licensed for use in the UK and is commercially available.