Vet Advice: Eradicating Mycoplasma bovis in New Zealand

Lung pathology in Mycoplasma bovis-infected cattle at 10x magnification. (

All responsible organizations establish goals for themselves. Less than 10 per cent ever achieve them. Goal-setting tips offered by many management gurus and business planners include:

  • Aim high, but start low, celebrate and keep going.
  • Don’t let others set the goals for you.
  • Be clear about what success looks like.
  • Understand why this goal is important.
  • Track your performance.

Controlling disease outbreaks in animals often follows this line of reasoning, especially production diseases that lack the dramatic consequence of things like African swine fever and foot-and-mouth disease. New Zealand’s goal of eradicating Mycoplasma bovis from dairy and beef herds defies the basic rules of goal setting.

Mycoplasma bovis in New Zealand

As Biosecurity NZ notes, Mycoplasma bovis is a bacterium that can cause a range of serious conditions in cattle, including mastitis that doesn’t respond to treatment, pneumonia, arthritis and late-term abortions.

The disease may be dormant in an animal, causing no symptoms at all. But in times of stress (for example, calving, drying-off, transporting or being exposed to extreme weather), the animal may shed bacteria in milk and nasal secretions. As a result, other animals may be infected and become ill or carriers themselves.

This is the first time it has been found in New Zealand. The bacterium is an Unwanted Organism under the Biosecurity Act 1993. Mycoplasma bovis is not listed with the OIE (the World Organisation for Animal Health) and doesn’t present a trade risk for New Zealand animal products.

Internationally, the disease is managed by farmers through:

  • Good biosecurity practices on their farms.
  • Careful selection of replacement stock and breeding bulls.
  • Keeping herds in a good state of health.

On farm, Mycoplasma bovis is spread from animal to animal through close contact and bodily fluids such as mucus and milking equipment. Calves can be infected by drinking milk from infected cows. Urine and feces are not regarded as significant transmitters of the disease, but the bacterium does survive for longer periods in a moist environment, such as in piles of moist feces and wet bedding material.

Off farm, the disease is mostly spread through movement of cattle from farm to farm. Movement restrictions preventing the spread of stock from infected properties are the most appropriate measures to contain Mycoplasma bovis. Farm equipment may play a role in the spread of the disease, especially equipment that comes into direct contact with infected animals, such as artificial insemination instruments.

Is eradication realistic?

Last year, the New Zealand government announced that it would try to eradicate the disease even though there has been no agreement on how long it might take. Eradication costs might reach a billion dollars.

Mycoplasma bovis is not a food safety risk. It is a disease that affects animal welfare and production. It affects only cattle, including dairy cows and beef cattle. It is common in many food-producing nations where infected animals that aren’t showing symptoms are processed for human consumption.

Keith Woodford is an honorary professor of farm management and agribusiness at Lincoln University. He has written extensively on New Zealand’s struggle with Mycoplasma and has had his finger on the pulse of how the eradication effort started and where it might be going. His views and the views of officials in the Ministry of Primary Industries (MPI) often conflict.

One deficiency in New Zealand’s eradication effort is the communication gap between producers and government organizations managing eradication and ongoing biosecurity activities. Strong feelings have been registered about government agencies stepping back and letting industry run the control effort, an eventuality that would probably guarantee abolishment of eradication as a realistic goal.

Criticism has also been levied that there is a lack of scientific scrutiny and veterinary oversight in the teams trying to run the eradication program.

It’s believed M. bovis had only been in New Zealand for 18 months when Dr. Merlyn Hay identified it in a dairy herd. At the time, she hoped it could be eradicated.

“It’s one of those things that we don’t know unless we try; it’s never ever been done before and we have an opportunity to try in this situation,” Hay stated, adding that she was “very hopeful” that it could be done.

Not a strong endorsement that eradication might be achievable.

Points of view differ around where and when infection started and how far it had progressed when discovered. Estimates vary from less than 50 to several hundred farms. There are still differences of opinion about what farm practices represent the greatest risk of transmission in an environment where individual herds were rapidly expanding, secure sources of replacements had diminished and management of cull calves was chaotic. Farm practices that favour transmission of M. bovis such as control of milk required to feed calves and biosecurity protocols limiting the spread of mycoplasma were not strictly enforced.

Industry and public support for investment in eradication that realistically could last for up to 10 years and cost nearly a billion dollars is in question. The cost effectiveness of pursuing eradication has yet to be established. There is still not a highly sensitive test for Mycoplasma in milk or blood. And there is a growing desire to live with the disease like the rest of the world.

In the words of Gordon Tredgold, leadership consultant: “I’m a big believer in the adage what gets measured gets done, but I am an even bigger believer in the power of motivation. If you want to set yourself a big bold goal, be clear about what success looks like, make sure it’s your goal and understand why it’s important to you. If you can do that then you will significantly increase your chance of being in that small group of eight per cent who achieve their goals.”

There is a serious question whether New Zealand will be in the eight per cent.

— Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen or WCABP.

About the author


Dr. Ron Clarke

Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen ([email protected]) or WCABP ([email protected]).

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