Equine influenza: the current state of play – May 2026

You are probably aware that there has been a recent surge in cases of Equine Influenza (which we will hereafter refer to as flu for simplicity).   Many areas of the UK have been affected, with new outbreaks popping up most days.  As a vet who has signed up to the national surveillance scheme, I receive a phone notification each time a diagnosis is confirmed by laboratory testing, and the phone has been pinging away with great regularity!

Like with humans, equine flu is always with us and it is unrealistic to think it will go away.  Some years will produce lots of cases and others very few.  You may well remember 2019, when some racing and competitions were abandoned.  Little did we know that our own human viral epidemic, and then pandemic, would follow with COVID-19.  Ironically, it is now felt that the human medics and strategists had been focussing too much on flu and not enough on coronavirus.  But I digress……

In 2019, over 400 ‘outbreaks’ of equine flu were confirmed by laboratory diagnosis.  It is important to understand what we mean by ‘outbreak’: a single sample showing up positive by PCR testing counts as an outbreak, but behind this result may be multiple other affected animals which were not tested, and probably others which are infected (and infectious) but not outwardly unwell.  It’s also worth bearing in mind that lots of horses which become unwell are never seen by a veterinary surgeon, let alone tested.  It therefore follows that those positive results are likely to represent the tip of the iceberg, similar to COVID-19.

Since 2020, confirmed outbreak numbers have varied from only 5 in 2025 (an extraordinarily low number, historically) to 58 in 2023.  When compared to the estimated number of horses in the UK (0.8 to 1 million, according to World Horse Welfare), this doesn’t sound like many, but flu has the tendency to punch above its weight because of its high level of infectivity and ability to massively impact the local and national equine industry as a whole, from elite racing yards to busy riding schools, as well as to private premises.

The Equine Infectious Disease Surveillance (EIDS) programme was formed in 2005 to record and monitor a number of infectious diseases that affect horses, including flu, strangles and Equine Herpes Virus. None of these conditions are Notifiable (i.e. have to be reported to the UK government) but all are of massive consequence to horses, owners, trainers and other stakeholders in the UK equine industry.  EIDS is primarily funded by the racing industry, who, arguably, have the most to lose from uncontrolled spread of disease, but the data generated is used by thousands of veterinarians and other equine professionals to inform their practice.

So far this year, EIDS have reported 44 individual outbreaks across 28 counties/regions in England, Wales and Scotland.  Northern Ireland, the north of Scotland and the south-west of England have not had any confirmed cases so far, probably representing areas which are more geographically isolated and/or with lower populations and movement of horses.  We are a long way from the 400 cases of 2019, and hopefully we will never get there, but this cannot be seen as anything but a surge in cases.

You can read the latest update here, with a map of current confirmed outbreaks:

https://equinesurveillance.org/landing/resources/EIDS_EI_update_07052026.pdf

The statistics show that most of these outbreaks have been confirmed in unvaccinated horses or horses with unknown vaccination status.  14% were in vaccinated horses. 61% cases were in horses which had recently moved premises, highlighting the importance of isolation for new arrivals.

Should we care?

I think we should care.  This is an unpleasant disease, causing fevers, enlarged lymph nodes, snotty noses, coughing, sore throats and sore muscles/joints.  If you have ever had flu, you probably didn’t feel like getting up for a few days.  We can only treat it symptomatically with bute or similar drugs, alongside good nursing care.  The good news is that most horses do fully recover within three weeks, with the worst over in a few days.  Rarely, a vulnerable horse may develop a secondary bacterial pneumonia, which is potentially fatal.

The youngsters and elderly horses are most at risk – some adult horses may shake it off without showing symptoms.  Unfortunately, these are the horses which are often unvaccinated.

A vet who diagnoses flu on a yard will recommend that movement of horses on or off a yard cease with immediate effect and does not restart until all cases have fully recovered (plus a margin of safety).  Because the virus can travel up to 5km and live on fomites for up to 48 hours (humans/water buckets/gateposts, etc!), it can be very difficult to isolate horses effectively.  Interruption of training and competition schedules will inevitably occur and there is the risk of reputational risk for commercial premises.

Should I worry?

We all became familiar with the concept of ‘risk-reduction’ rather than ‘risk-elimination’ during the COVID-19 pandemic and that applies equally well here, too.  There is no need to panic, but there absolutely is the need to assess the risk level of your own situation.  If you not comfortable doing this, your own vet will be able to discuss it with you.

Think about:

• Is it your own private premises, with you in control of who comes and goes, and no adjoining yards?
• Are you stabled on a livery yard with multiple horses and owners, some of whom travel to training or competitions?
• Do new horses come to your yard and are they effectively isolated? (Most isolation, in my opinion, is not worthy of the name…….discuss!)
• Are you travelling to events and gatherings?

An example of a very low risk situation would be a property with a handful of horses living there who do not leave the premises and do not have any equine neighbours.

An example of a very high risk situation would be a dealer’s yard with multiple unvaccinated horses arriving together in group transport on a regular basis.

Most yards will fall somewhere in between these two extremes.

What can I do?

• Isolate new arrivals to a yard as effectively as your situation allows. No, no one is likely to have an isolation field 5km away from other horses, but close contact, shared airspaces and communal equipment are going to massively increase risk, so try to find an alternative space for the horse to stay in for 2-3 weeks. Use overalls and overboots when dealing with this horse. Take its temperature daily to look for a spike above 38.5C.  I would also suggest carefully assessing the risk profile of the individual horse if you plan to vary the above regime.  Like with humans, vaccines reduce the severity of disease but do not entirely prevent it, so cannot be seen as a panacea.
• Vaccinate as many horses as possible. Herd immunity is best if most horses are vaccinated (ideally 90%).  Current estimations suggest that only 30-50% of the UK equine population are vaccinated, which is pretty poor.  I could be wrong, but I suspect that many (most?) owners vaccinate their horse because they have to for competition, rather than primarily for health benefit.  I think we should shift our thinking to be a bit more altruistic and concentrate on disease prevention – we also protect our friends’ horses by vaccinating our own, because vaccinated horses shed less disease.  Vaccination costs £40-£60 on average per dose, plus visit fees, if applicable.  Don’t wait until a youngster is competing to start vaccines – do it from 6 months of age – and don’t give up on the older ones once they’ve retired.  Think who the NHS considers it worth vaccinating: kids, the elderly and people with underlying medical conditions – not the 28 year old running his third marathon.
• Consider vaccinating your horse early. For most non-racing and non-FEI competitions, annual vaccination is mandatory.  However, antibody levels start to drop off from 6 months, so if you feel you are in a high risk situation, an early booster is sensible.
• View any horse which is off-colour with suspicion: arm yourself with an inexpensive rectal thermometer and take their temperature, if it’s safe to do it. Move it to an isolation space if it is elevated (above 38.5C is almost always abnormal, but between 38-38.5C should, perhaps, be viewed cautiously, because most horses sit at 37.something unless recently exercised, well rugged or on a hot day). This video by the BHS shows how to do it:

https://www.bhs.org.uk/horse-care-and-welfare/health-care-management/horse-health/equine-diseases/equine-influenza/

• Recognise the risk that we all pose! Owners, vets, farriers, equine dental technicians, saddle-fitters, physiotherapists, etc, etc, etc…….    We should all be taking sensible precautions relevant to our own profession or role.

Let’s hope that the current spread of flu can be slowed and reversed.  We can all play our part! And one final thought – don’t forget about strangles! Between May 2025 and April 2026, there were 464 current cases, which eclipses flu in terms of numbers of outbreaks.  Isolation, testing and vaccination are just as relevant for the prevention of strangles, so throw that into your risk assessment while you are thinking about it!