You may have heard the term Mycoplasma associated with multiple different problems in both adult cattle and calves. Although it is not a ‘new’ problem, it is a complicated bug and we are still learning exactly how and when it causes disease. Sarah gives us more information…

Mycoplasmas are a group of very small bacteria and in the UK Mycoplasma Bovis is the most common type associated with disease in cattle. The signs seen depend on which part of the body it affects and can include mastitis, joint infections, pneumonia and inner ear disease.

Respiratory disease is one of the most common problems we see in calves infected with Mycoplasma. Signs can vary and the response to treatment is often poor if not caught early. Below I have described a recent outbreak of Mycoplasma in calves seen on a farm and how we are managing the disease in this herd.

Outbreak in calves on farm

Earlier in the year I was asked to examine a group of very sick calves which were not eating. These calves had high temperatures, snotty noses and crusty eyes. A high proportion also had an ear droop on one side with crusty discharge coming from the ear canal.

A more unusual symptom seen was swelling over the eyes and forehead in the worst affected.
The outbreak was extremely widespread with nearly all pre-weaned calves affected regardless of age.

There are several samples which can be taken to determine the cause of respiratory disease. In this case we opted to perform a post-mortem on one of the worst affected animals as we thought this would be the most likely way to get an answer quickly. The findings were dramatic and really explained why the calves were appearing so sick.

The image above shows the nasal passages full of pus and infected material; this was the same for the inner ear. The lungs themselves showed no signs of disease. The lab confirmed the presence of Mycoplasma and suggested that the swelling seen on the foreheads was the result of the immune glands being so enlarged they were blocking fluid drainage from the head.


Mycoplasma infection will not respond to treatment with some antibiotics so during the outbreak we ensured any suspect cases were treated promptly with an anti-inflammatory and an appropriate antibiotic. In-contact calves were checked regularly and temperatures taken to pick up early signs of disease.

Outbreaks of this disease can be associated with poor immunity so the farmer worked to ensure colostrum transfer was adequate. We screened the group for BVD as this can also make animals more susceptible to disease.
Spread of infection between the calves can be through direct contact and via feeding equipment. We recommended disinfecting feeding buckets after each feed and numbering them so that the same bucket could be returned to the same calf.

As introduction of infection was thought to have come from the adult herd, we recommended limiting all contact between cows and calves and removing calves from the dam as soon as possible after calving.

Although calves were fed milk replacer from two days of age, it was possible that infection was coming through colostrum. Mycoplasma can be readily destroyed in colostrum through pasteurisation so investing in a pasteuriser was recommended. For this size farm (~180 cows) and on an all year round calving pattern the Store and Thaw machine is probably the most affordable option which can pasteurise individual bags of colostrum as well as defrosting frozen colostrum very quickly.

Although there are no commercial vaccines available for Mycoplasma, a vaccine can be produced using the specific strain identified on your farm. For now, we are prioritising preventing introduction through good biosecurity and limiting the routes of transmission from the adult cows to the calves, however if we continue to see outbreaks of disease, vaccination will be reconsidered.

Mycoplasma in Calves
Discharge seen coming out of the ear.
Mycoplasma in Calves
Crusting around the nose and swelling above the eyelids.
Mycoplasma in Calves
Nasal passages full of pus and infected material.