Never Miss a Post

Join 10,000+ subscribers and get our latest articles via email.

How to Identify and Manage Equine Influenza

How to Identify and Manage Equine Influenza dressage

Equine influenza is not the most dangerous disease that your horse may succumb to, and most horses recover quickly and fully with rest and supportive care. However, the condition can be a nuisance, especially on large yards, as it is highly contagious.

The incubation period for the disease is only a day or two, and, in no time at all, a whole barn full of horses can be coughing and feverish, almost before you realize that one of them is sick.

The recovery period for equine flu can be long, and that will ruin your carefully planned training and competition schedule.

In this article, we explain how to identify and manage equine influenza, including taking a closer look at the current vaccination strategy.

What is equine influenza?

Equine influenza, also known as equine flu, is a highly contagious respiratory tract infection.

The virus that causes the disease is primarily airborne. That means it spreads incredibly quickly, especially through groups of horses that are turned out together.

Even horses in adjacent paddocks can be at risk, as the equine influenza virus can travel for up to half a mile if it’s carried on the wind.

Also, the virus can be transmitted via people, horse-to-horse contact, on tack, equipment, and even on feed.

Signs and symptoms

So, how do you know if your horse has equine flu?

The symptoms of equine flu include:

  • Nasal discharge
  • Dry, hacking cough
  • Fever
  • Lethargy
  • Poor appetite

In extreme cases, especially in foals, pneumonia can occur, which can be fatal.

The severity of the symptoms depends on the individual horse. Factors such as age, exercise level, stress, and the potency of the virus all come into play. Also, the horse’s vaccination status can alter symptom signs.

Essentially, horses that have never been vaccinated are likely to suffer severe symptoms, whereas those who have been vaccinated will display very mild signs, if any, at all.

What’s the prognosis?

Most animals recover within two to three weeks of getting equine flu. However, in some cases, a cough can be persistent, taking many months to clear up completely.

Sometimes, a horse can suffer heart muscle inflammation (myocarditis), which causes a permanently irregular heartbeat.

Groups that are most at risk of contracting equine flu

Some horses are more at risk of contracting equine influenza than others.

  • Young horses between one and five years
  • Horses that frequently travel to shows
  • Horses that live on very large yards
  • Horses that have not been vaccinated

The good news is that there are several very effective flu vaccines available, which will prevent your horse from contracting equine flu. Also, there are many steps that you can take to prevent your horse from contracting the virus.


There are two clear strains of equine flu that currently affect horses. The American strain of equine flu is the most prominent and is responsible for virtually all the flu outbreaks worldwide in recent years. However, there are several countries that hold influenza-free status, including Australia, New Zealand, and Iceland.

There are three forms of equine influenza virus vaccine that are currently marketed:

1. Inactivated vaccines

Inactivated vaccines are very effective in protecting horses against equine flu and in preventing “shedding” by horses that carry the virus but never succumb to its effects or display symptoms.

These vaccines are typically given in two shots. The first being a priming shot and the second a booster.

Inactivated vaccines are generally used as pre-foaling boosters that can increase colostral antibody levels to provide protection for unborn foals against the virus.

2. Modified-live (MLV) cold-adapted vaccines

MLV vaccines are administered intranasally in one single dose and are proven to be effective for up to 12 months.

These vaccines can be used safely in foals of six months of age or older. However, this vaccine is not recommended for use in mares in late pregnancy.

3. Canary pox vector vaccine

Canary pox vector vaccine is administered by two-stage intra-muscular injection and provides protection for up to six months; therefore, boosters are recommended every six months.

The vaccine can be given safely to foals as young as four months of age.

Outbreak mitigation

If there’s an outbreak of equine influenza in your area, your vet may recommend vaccination to boost immunity.

Previously vaccinated horses can be given a shot of any vaccine.

Unvaccinated animals or those with an unknown history should be given an intranasal vaccine because protection is usually achieved within seven days. A canary pox vectored vaccine is generally used for this purpose.

Ongoing protection

To ensure that your horses are protected from the debilitating effects of equine flu, you must put in place a regular vaccination schedule.

Your vet will advise you on the correct vaccination schedule for your yard based on the type of vaccine that he has used.

Compulsory vaccination

If you compete on your horse, many of the venues that you attend will insist that your horse is vaccinated against equine flu before allowing you to enter the showground.

Also, most of the main sport governing bodies require that horses are vaccinated against flu before you can register your horse with the organization. So, remember to check the current rule book for the latest regulations.

How to prevent equine influenza

Here’s an overview of some of the steps you can take to prevent your horse from catching equine flu.

1. Vaccination

As mentioned above, the most effective way of preventing your horse from catching equine influenza is through an ongoing vaccination program.

2. Reduce horse-to-horse contact

Nose-to-nose greetings can allow the equine flu virus to pass from one horse to another. Remember that not every contagious horse looks sick, so it’s impossible to know if there’s a threat or not.

If you take your horse off the yard, don’t allow him to make physical contact with other horses.

3. Don’t share equipment

The flu virus can survive for many hours on surfaces, including tack, brushes, etc. Never borrow someone else’s kit when you’re away from home. If you really must share an item, always clean it thoroughly first, using an antibacterial soap or wipe.

If your horse is to use a temporary stable at an event, use disinfectant wipes to clean all exposed surfaces, especially the top of the door, hayracks, and feed bucket holders.

4. Don’t use communal water troughs

The flu virus is carried in water droplets, so it should come as no surprise that the organism can survive in water for hours or even days.

At home, you know the vaccination status of your yard mates, but away from home, you don’t. So, never use public troughs or communal buckets, and don’t allow your horse to lick salt or mineral blocks.

Wherever possible, take your own buckets to shows.

5. Temporary quarantine

If you have horses in your yard that stay away from home at shows or clinics, there’s a possibility that they could pick up the virus or other illnesses.

For that reason, you should keep these traveling horses separate from those who never leave your yard, especially foals, youngsters, and pregnant mares. The segregation should last for at least a week.

6. Quarantine new arrivals

Any new horses arriving on your yard should be placed in quarantine for at least two weeks.

You can read more about how to quarantine horses in your yard in the article. 

7. Clean up

Don’t forget that the virus can pass between horses via tack, rugs, your clothing, and on your hands. So, wash your hands with antibacterial soap or use hand sanitizer gel after handling every horse that you care for.

If you have a sick horse to look after, use a dedicated set of tools for that horse.

How to care for a horse with equine flu

If you think that one of the horses in your care has equine flu, isolate the horse right away from the others in your yard. That could mean putting the horse in a separate paddock or in a stable at the end of the aisle, although, ideally, you should use an isolation box.

Use fans to direct air from inside the affected horse’s stable out through a door or window, well away from the other horses.

Routinely check all the other horses for signs of an elevated temperature.

If possible, ask someone else to care for the other horses, wash your hands when you’ve finished attending to the sick horse, and change your clothes.

There’s no specific treatment for equine flu other than supportive care and rest while the infection gradually runs its course.

Your vet might prescribe anti-inflammatory drugs to bring down the horse’s temperature, which should make him comfortable so that he will continue eating and drinking.

Recovery and recuperation

After the initial infection has subsided, the horse will need time to fully recover and recuperate.

The flu virus damages the tiny hair-like structures (cilia) that line the horse’s trachea which helps to clean it of dust and debris that the horse inhales. Until that damage heals, the horse will be susceptible to secondary infections, which manifest themselves as thick yellowish/white nasal discharge. At worst, the infection can progress into pneumonia.

As a general rule of thumb, the horse should be allowed at least three weeks’ rest or one week of rest per day that he had a fever. During that time, keep the horse in a clean, dust-free environment to aid healing.

Once the horse has recovered, disinfect the tools you used to care for him, his stable, his rugs, feed buckets, water bowls, and any other equipment that he came into contact with.

Ridden exercise

It’s extremely important that you don’t start riding your horse too soon after he’s suffered a bout of equine flu.

Even very light ridden work places demands on the horse’s respiratory system, and riding him while his airways are still damaged can seriously put back his recovery.

In conclusion

Although equine flu is rarely fatal, it is a highly contagious disease that can put a horse out of action for many weeks. That’s not what you want at the best of times, but it is especially heartbreaking if you have to miss out on competing at championships and other important events as a result of a preventable illness.

You can stop equine influenza from attacking your horse by putting in place a veterinarian-approved vaccination program for your yard.

Do you have any tips and tricks to manage equine flu? If you do, we’d love to read your story in the comments box below.

Related Reads: 

Leave a comment...

Your email address will not be published. Required fields are marked *

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}

There's more where that came from...

Check out our selection of related articles. 

How to Lunge Your Horse
How to Clip Your Horse
How to Identify and Manage Navicular
Plants That Are Poisonous to Horses
How to Long-Rein Your Horse
How to Fence Your Horse’s Fields and Paddocks