Equine influenza — all you need to know about horse flu

Firstly, please could you explain what equine flu is?

It’s a respiratory disease and an airborne virus, which means that when an infected horse coughs they can release contaminated droplets into the air, which can cause the virus to be spread. 

Because of its airborne nature, it’s a highly contagious disease, with not only horses in proximity affected. 

The virus can be carried about 25 meters on the air but given the correct conditions this can extend to up to five kilometres.

So, is the disease only limited to being spread through the air?

No. While it’s an airborne virus, the disease can be spread through direct contact between horses or indirectly, through simple things like sharing feed buckets or by not disinfecting stables properly between horses.

To help prevent the spread of the disease, there are some easy things you can do: 

• Keep your horse’s vaccinations up to date
• Don’t share water sources away from the yard
• Prevent contact off your yard
• Keep an eye on their temperature
• Provide each horse with their own equipment 
• Disinfect your boots, wash hands and change outer clothing, when visiting other yards
• Clean and disinfect equipment and transport after each event.

We have a handy downloadable guide which provides a helpful reminder on the steps you can take.

What are the most common signs a horse may have equine flu?

There are seven common symptoms associated with equine flu:

1. An increased temperature above 38.5C (101.3F) for one–five days (this can happen before any visible signs are shown by your horse) 
2. A frequent dry, harsh cough
3. A clear, watery nasal discharge that may become thick and yellow or green in colour 
4. Loss of appetite 
5. Your horse is lethargic 
6. Swollen and painful glands under and around their jaw 
7. ‘Gags’ when eating.

But, it’s really important to remember that all horses are different and some unwell horses may not immediately show signs or only show very mild signs.

If you suspect your horse may have equine flu, what steps should you take?

If your horse is showing symptoms of equine influenza, then acting fast can help reduce the spread of the disease:

1. Isolate the horse as soon as possible
2. Call your vet – they’ll likely arrange to take a swab or blood test to confirm that it’s in fact equine flu and support you setting up isolation
3. Stop all horse movements on and off your yard
4. Continue to maintain good disease prevention practices on your yard.

Infected horses could continue to spread the virus through coughing for up to ten days, but it can be longer.

How should you isolate your horse?

It’s important to isolate your horse quickly if a case is suspected, or confirmed, to try to prevent further spread. We know that this can be tricky, depending on your set-up. When isolating, it’s important to remember:

• To try to keep 25m distance from other horses – this could be done by designating a specific stable or by moving other horses to a different field
• Mark the space clearly as an isolation area
• Disinfect all equipment on the yard
• Use separate equipment, water and feed buckets for the isolated horses 
• Keep everything you need within the isolation area including disinfectant, hand sanitiser and rubbish bins
• Designate carers for the horses in isolation and if needed attend to these horses after the others on the premises 
• Notify people and places from the past three weeks who may have been in contact with your horse.

We have some helpful detailed guidance on how to set up a traffic light system to isolate horses into groups, which can be found and downloaded here. 

How do you care for a horse with equine flu?

Unfortunately there’s no direct treatment, the best thing is to provide care and lots of rest. 
Try to keep dust levels as low as possible to stop any additional irritation to their respiratory system. 

It’s important to be patient and not to rush recovery - it may take several weeks for your horse to fully recover. If they aren’t properly cared for, there’s a risk of future complications, so get your vet’s advice before you return your horse to work to make sure they’re recovered and ready.

If a horse is vaccinated will they be less affected?

Vaccination remains an important way to minimise the risk of flu. If your vaccinated horse becomes ill with the flu, they won’t be as severely affected and will suffer for less time compared to an unvaccinated horse. Your vet can advise on the most current vaccine available.

When more horses are vaccinated, the spread of the disease is reduced. By vaccinating your horse, you’re not only protecting them but you’re helping to reduce the risk of spread to others, which increases the UK’s herd immunity.

Where can people find more information and guidance?

We have some fantastic information available on our website within our Horse Health and Equine Disease pages. Make sure you look out for an in-depth article on equine influenza in the 2026 summer issue of British Horse.

Links:

• Equine diseases advice and information - advice specific to donkeys is available from The Donkey Sanctuary
• Equine influenza advice and information
• Equine disease prevention at events.