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Equine Influenza

Equine InfluenzaEquine Influenza

Equine Influenza

Equine Influenza, or ‘flu’ is an infectious disease caused by the influenza virus and can be passed very easily from one horse to another. The virus reproduces in the nose, throat and windpipe (respiratory tract) and is spread when the horse breathes, coughs or sneezes. The virus can also be passed on by direct contact between horses and by handlers, so good hygiene is very important.

Flu Virion

Flu Virion

AHT Top Tip: Flu is easily passed on through contact so make sure you wash your hands between caring for each horse, avoid sharing or clean equipment used by more than one horse and don’t allow sick horses to come into contact with others.

What to do

If your horse is showing signs of flu then you should call your vet as soon as possible. Your vet will be able to take swab and blood samples from your horse to confirm the infection. Your vet will then be able to advise you on the most appropriate treatment and on the long-term recovery of your horse. They can also help you identify other susceptible horses and suggest strategies to limit the spread of the disease.

AHT Top Tip: As soon as you notice your horse looking under the weather, call the vet. The sooner you contact them to diagnose the problem, the sooner you can get your horse on the road to recovery.


It takes time for the lining of the respiratory tract to fully recover after infection with flu. During this time the horse should not be put under any stress or strenuous exercise, as they will be predisposed to developing other respiratory infections, including secondary bacterial infections.

AHT Top Tip: A good rule of thumb is for every day that your horse had a raised temperature they will need at least a week off from exercise.

How to prevent infection

In the UK most horses will come into contact with the influenza virus during their lifetime. There are risk factors associated with influenza infection, which include being compromised by injury or illness, being very old or very young, and not being regularly vaccinated. The main way of controlling equine flu is achieved through regular vaccination, which is given either once or twice a year. Vaccinated horses may not show signs of flu themselves, but they are still able to carry the virus and pass it on to other horses.

AHT Top Tip: Vaccination strategies for companion ponies or older horses should be carefully considered as even if they don’t leave the yard themselves, they are at risk of being infected by other vaccinated horses that do travel.

How to prevent spread

If you suspect a horse has influenza, it is important to isolate it from other horses. The virus spreads very quickly and horses can be infected before they show any signs, so if it is appropriate it is sensible to also isolate horses that have been in contact with the infected individual. The virus can survive outside of the host for limited periods and so objects such as head collars, tack, grooming kits and feed and water buckets can also be sources of infection. However, most disinfectants are sufficient to destroy the virus.

AHT Top Tip: It is good practice to isolate or quarantine new arrivals to the yard for two weeks. Any signs of infection should become apparent during this time and will therefore reduce the risk of spreading the disease to other resident horses.

What we do

At the AHT we run a surveillance scheme for equine influenza where we are able to offer free testing for the virus with funding from the Horserace Betting Levy Board. We use the samples that are submitted by vets to find out where and how frequently outbreaks of flu are occurring in the UK. We also monitor how the virus is changing over time compared to current vaccine strains. Together with surveillance data from around the world, this information is used to recommend suitable strains to be included in vaccines.

Swab Kit Equine Influenza

Swab Kit

In the last two years there have been 52 recorded outbreaks of equine influenza in the UK, however this may just be the tip of the iceberg and the actual number of outbreaks may be much higher. If you would like to find out more about equine influenza, and to tell your vet about our surveillance scheme, please visit You can also keep up to date with any recent outbreaks of flu by following @equiflunet

Flu Surveillance Facts:

  • So far in 2016 there have been confirmed outbreaks in Stirlingshire, Fife, Kent and Hampshire.
  • So far the surveillance scheme has received 282 blood and swab samples in 2016
  • Over 300 equine vet practices are signed up to the Equine Influenza Surveillance Scheme
  • Over 850 cases of suspected horse flu have been tested for free on the Surveillance Scheme since January 2014.
Clinical Signs


Harsh dry cough

Raised temperature

Laboured breathing

Clear or white nasal discharge

Enlarged lymph nodes in the throat

Quiet or depressed


Loss of appetite

Spreads rapidly between horses

With special thanks to the Animal Health Trust


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