Horse Flu: Equine Influenza Signs & Treatment

Signs

Signs of equine flu include:

An increased temperature above 38.5^oC (101.3^oF) for one to five days. This can happen before any visible signs are shown by the horse. Watch our video below on how to take your horse’s temperature, to establish what their normal healthy temperature is.
A frequent dry, harsh cough
A clear, watery nasal discharge that may become thick and yellow or green in colour, a few days later
Loss of appetite
The horse is lethargic
Swollen and painful glands under and around the jaw
‘Gags’ when eating

The disease can weaken a horse, leaving it vulnerable to secondary infections including bronchitis, pneumonia, swelling of the lower limbs and sore muscles. Such complications are particularly worrying in young foals, elderly animals and those with a pre-existing respiratory disorder. In serious cases this can be fatal.

Watch

How to take a horses temperature

Treatment and Management

If flu is suspected, isolate your horse and contact your vet. It is likely that a swab will be taken and possibly a blood test.

Learn more about the steps to take in the event of a disease outbreak.

There is no direct treatment for flu, much like people with flu, the best treatment we can provide is supportive care and plenty of rest.

The dust levels in the horse’s environment should be kept as low as possible, so the respiratory system is not further affected.

It can take several weeks for the horse to recover and return to full health. If not appropriately managed, there is also the risk of complications such as relapse, permanent damage to the heart muscle, infections of the upper and lower respiratory tract and pneumonia¹. Seek your vet’s advice before returning your horse to work to prevent these occurrences and ensure they aren’t over stressed or over worked.

Spread of Equine Influenza

Equine influenza is an airborne virus and when an infected horse coughs, droplets are released into the air. In certain situations, the wind can spread the virus up to 2km². Equine flu can also be spread via direct contact from horse to horse or indirectly, for example by handlers, equipment, feed buckets, sharing horse transportation and in stables that have not been sufficiently cleaned and disinfected between horses³. The incubation period (time between becoming infected and the onset of signs) for the disease is between one and five days. Therefore, an influenza outbreak can quickly spread between horses, particularly among unvaccinated horses².

Preventing Disease Spread

Maintaining good health and hygiene management practices on your yard, with the correct disease prevention measures in place, can also help to prevent the spread of equine flu and other diseases.

Learn more about the simple steps you can take to prevent the spread of disease.

Vaccination

Vaccination remains the most important way of decreasing the risk of flu.

When the vet arrives to vaccinate your horse, make sure their passport is available so the injection can be correctly recorded. If you are worried that your horse might not be well, if, for example, they are lethargic or not eating as usual, speak to your vet ahead of vaccination. It may be that your horse is incubating a disease and therefore vaccinating at this point could cause a negative reaction.

Flu is an adaptive virus and can change over time. As a result, although vaccines are available, it can be difficult to keep them fully up to date with the most current strain. This means the vaccines may fail to provide full immunity. This has led to cases where vaccinated horses can suffer with flu. However, vaccinated horses will not be as severely affected and will suffer for less time compared to unvaccinated horses⁵. They will also shed less of the virus, reducing the risk of spread to others². Your vet will be able to advise on the most current vaccine available.

Initial Course – First Year

The vaccination programme begins with a series of injections given over the first year, which is then continued by boosters to maintain cover against the virus. It is important not to allow the booster to lapse, because even being one day late will result in the initial vaccination programme having to be restarted, which will be costly for the owner.

Boosters

Vaccines help to protect the horse by providing a strong antibody response. Unfortunately, this is short-lived, which is why horses need to receive regular booster vaccinations. As a minimum, all horses should be vaccinated annually (no more than a year apart). Six monthly booster vaccinations are an option and will help to maintain the horse’s antibody levels, leading to greater protection against equine flu^4,5. If you are competing with your horse, make sure you check the specific rules relevant to the organisation, as some request that horses have a six-monthly booster.

Herd Immunity

Where a higher percentage of the equine population is vaccinated, the spread of the disease is ultimately reduced. For herd immunity to work, a large proportion of the population must be vaccinated. It’s estimated that only 30% of the UK equine population is vaccinated against influenza⁶. By following the advised vaccination procedure, you are not only protecting your own horse, but also increasing the UK’s herd immunity.

Shows and Events

Carrying your horse’s passport is a legal requirement when transporting and shows or events may conduct vaccination checks. It’s essential to check with the show organisers or relevant governing body on their specific vaccination requirements. If your horse doesn’t meet their requirements, it’s likely that you will not be allowed to compete. If you hire equestrian facilities, it’s important to check the vaccination rules of the venue.

When attending shows or events, it’s important that good biosecurity practices are maintained at all times to prevent the spread of disease.

Learn more about preventing the spread of disease at events.