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Key Facts About Equine Influenza

Equine influenza (flu) is a respiratory disease caused by a highly contagious virus. It is widespread (endemic) within the UK and therefore it is important that we recognise the signs.

What is equine influenza?

Equine influenza (flu) is highly contagious so will spread rapidly through an unvaccinated population of horses. It does not usually cause long term or fatal illness, but can lead to horses having large amounts of time off work. It also has financial implications in terms of cancellation of events and the cost of treatment. It can also lead to serious complications in very young or old horses.

How is equine influenza spread?

Equine influenza is an airborne virus and can spread quickly and easily through a yard. Under favourable weather conditions it can spread up to 5km. It can be transmitted by direct horse-to-horse contact and also via people, tack, feed and equipment.

What are the signs of equine influenza?

Signs are caused by an infection of the respiratory tract and typically include:

  • Dry, hacking cough
  • Nasal discharge
  • Fever
  • Lack of appetite
  • Lethargy

Pneumonia can occur in some individuals, particularly foals.

Clinical signs of equine influenza include nasal discharge.
Clinical signs of equine influenza include nasal discharge.

Do all horses show the same signs of equine influenza?

The severity of signs depends not only on numerous horse-related factors such as age, stress, exercise level and vaccination status but also on how potent the infecting virus is. Unvaccinated horses, who have never been exposed to the virus before are likely to show marked signs whereas vaccinated horses should only display mild signs, if any at all.

Can my horse die of equine influenza?

The disease carries a low rate of mortality so it is unlikely that your horse will die from infection. However, the virus can cause a form of pneumonia which may prove to be fatal in foals or yearlings.

Are there any long term consequences of equine influenza?

Most horses recover within two weeks however in some horses a post-viral cough can persist for a much longer time and in some individuals it can take up to six months to regain full health. There is also the potential that horses can develop sore muscles and myocarditis (heart muscle inflammation), which can subsequently cause an irregular heartbeat.

How is equine influenza treated?

There is no specific treatment for equine influenza and although antibiotics may be useful to control a secondary bacterial infection they will not treat the virus itself. Your horse will need a minimum of six weeks rest to recover and your vet will advise you on this.

Can I exercise my horse as soon as it has stopped coughing?

Following a bout of flu it is important to give a horse complete rest for at least six weeks. Without rest the potential for long term consequences increases.