Equine influenza is a highly contagious respiratory disease that continues to pose a significant risk to horse health and the wider equine community. With cases reported in multiple regions and the potential for rapid spread, understanding how the virus works and how to manage it is essential for horse owners, yard managers and competitors.

What is equine influenza?

Equine influenza is a viral infection affecting the respiratory system of horses, donkeys and mules. It spreads quickly in environments where horses mix, such as yards, competitions and during transport, and can cause significant disruption when outbreaks occur.

Symptoms of equine influenza

Horse owners may first notice that something is not quite right. A horse may appear subdued, quieter than usual or off its normal routine, with a slight drop in appetite or energy levels. In some cases, performance may dip before more obvious clinical signs develop. As the illness progresses, symptoms typically become more noticeable and can escalate quickly. Common signs include:

• High temperature (fever)
• Persistent, dry cough
• Nasal discharge
• Lethargy or dullness
• Loss of appetite
• Reduced performance

What is equine influenza caused by?

Equine influenza is caused by strains of the influenza A virus that target the respiratory tract. The virus damages the airway lining, making it harder for the body to clear infection and increasing the risk of secondary complications. As strains evolve, vaccines are updated to match those in circulation, making regular vaccination an important part of prevention.

Can horses recover from equine influenza?

Most horses recover fully with appropriate care, although recovery can take several weeks. Rest is essential to allow the respiratory system to heal properly, and returning to work too soon can delay recovery or lead to complications. Younger and older animals, or those with underlying health conditions, may require closer monitoring.

How do you treat influenza in horses?

There is no direct cure, but supportive care is usually effective. Management focuses on rest, good stable conditions and veterinary oversight. Anti-inflammatory medication may be used to control fever, while antibiotics may be prescribed if secondary bacterial infections develop. Isolation of affected horses is crucial to prevent further spread.

How contagious is equine influenza?

Equine influenza spreads extremely easily. It is transmitted through respiratory droplets when an infected horse coughs, as well as via contaminated equipment, clothing and human contact. The virus can also travel short distances through the air, allowing outbreaks to escalate quickly in busy environments.

The importance of vaccination

Vaccination plays a central role in protecting against equine influenza and limiting its spread. While it may not completely prevent infection, it significantly reduces the severity of symptoms and the amount of virus shed, helping to protect both individual horses and those around them.

Vaccines are regularly updated to reflect circulating strains, which is why keeping vaccinations up to date is essential. Most competition bodies require proof of vaccination, and lapses can result in horses being unable to compete or travel.

Even in vaccinated populations, outbreaks can still occur, but they are typically less severe and easier to control. This is why vaccination should be seen as part of a wider biosecurity approach, rather than a standalone solution.

Prevention and biosecurity in the UK

Reducing risk relies on a combination of vaccination and strict biosecurity. Horse owners should follow recommended vaccination schedules, isolate new arrivals, avoid sharing equipment, and maintain good hygiene practices. Monitoring horses closely for early signs of illness can help prevent wider outbreaks.

Why it matters

Outbreaks can lead to yard closures, cancelled competitions and restrictions on horse movement. Maintaining good biosecurity and keeping vaccinations up to date helps protect both individual horses and the wider equestrian community.