Equine Influenza

About the Disease

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What is Equine Influenza?

Equine influenza (EI) is an acute, highly contagious, viral disease which can cause rapidly spreading outbreaks of respiratory disease in horses, donkeys, mules and other equine species. EI would have a major impact on the Australian horse industry if it were to become established here.

The disease is not generally fatal to horses however, fatalities may occur especially in old or infirm horses and young foals.

How is EI spread?

The disease is easily spread by:

  • direct contact between infected and susceptible horses
  • indirect contact with contaminated tack or equipment
  • susceptible horses occupying buildings or vehicles recently occupied by diseased horses
  • contact between contaminated horse handlers and healthy horses.

Can people catch EI?

Transmission of EI virus to humans has not occurred during outbreaks of EI in horses.

EI poses no threat to people, however it can be spread from people to horses very easily via infected skin, hair and clothing.

How can you tell if a horse has EI?

The main signs of EI are usually a sudden increase in temperature (to between 39°C and 41°C); a deep, dry, hacking cough; and a watery nasal discharge, which may later become thick and smelly.

Other signs can include depression, loss of appetite, laboured breathing, and muscle pain and stiffness.

Recovery usually occurs after a couple of weeks but horses need to be rested for a further period to avoid complications.

Do carrier animals exist?

Once an animal has recovered and sufficient time (30 days) has elapsed they pose no risk to other horses.


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What is the treatment for EI?

There is no specific treatment other than rest and supportive treatment for the fever and cough.  However, some horses (eg. those worked or stressed while sick or during recovery) may develop secondary bacterial bronchitis or bronchopneumonia and can die. These animals can benefit from antibiotics and other therapies.

Horses that get infected with EI need to be rested for at least one week for every day of coughing eg. if the horse coughs for 5 days, it needs to be rested for 5 weeks.

Are infected horses destroyed?

Horses are not killed. Infected horses or donkeys are simply quarantined until they return to full health. Quarantine is critical to help prevent the disease from spreading.

Is there a vaccine?

During Australia's EI outbreak in late 2007/early 2008, a vaccine was specifically imported to control the disease. 

More on the use of the vaccine is below.

How was EI contained and eradicated in Australia?

Australia is the only country that has been able to eradicate this disease.  Eradication was achieved by implementing a number of measures in accordance to the nationally agreed disease response manual.

The control and eradication measures are described below:

Movement Controls

The initial national horse standstill and subsequent movement restrictions, combined with strong biosecurity messages, were effective in containing the disease to areas in NSW and south east QLD. The affected areas were zoned according to the risk of infection:

  • ‘purple’ and ‘red’ zones were infected areas
  • 'amber’ zones were buffer areas around infected areas
  •  ‘green’ zones were areas in QLD and NSW that were not infected, and
  •  ‘white’ zones were the remaining states and territories in Australia that were not infected.

As the outbreak progressed, horse movements were carefully managed and only permitted where risk-based assessments determined that the risk of transferring disease to another area was very low. This was successful because the disease never spread to other Australian states and territories and it was contained to defined areas of NSW and QLD.


Buffer zones and ring vaccination was used to contain areas of high concentrations of EI in NSW and QLD.

Vaccinations were also used to protect high-value horses and to increase immunity in horses that were in uninfected areas.

The use of the vaccine ceased once Australia was declared provisionally free of the disease in March 2008.

Industry and Public Support

The success of the eradication program was highly dependent on the support of all Australian horse owners, including those in the racing , competition and eventing, breeding sectors and the recreational sector.

National horse industry representatives were involved in the development of disease control policies and communication at all levels (national, state and local). 

Laboratory Support

The disease was quickly identified and new tests developed by the Australian Animal Health Laboratory (AAHL) at Geelong, Victoria. These tests were then transferred to state government laboratories and used for rapid confirmation of infection and later in proof of freedom testing. The design of the tests allowed large numbers of horses to be tested within a very short time.

Keeping Australia free of EI

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Ongoing Biosecurity

Despite EI having been eradicated from the Australian horse population, horse owners and handlers are strongly encouraged to maintain good biosecurity.

If you own or work with horses and donkeys please see our Horse and Donkey Biosecurity which has useful information on how to protect your animals from pests and disease.

More information

Information about current exotic pest and disease incursions can be found on the Outbreak website.