HORSES · Condition guide
Influenza in horses: what real veterinary cases show
Equine influenza is a highly contagious viral infection that affects the respiratory system of horses. It is caused by strains of the influenza virus and is one of the most common respiratory diseases in horses worldwide. The virus spreads rapidly among horses, especially in environments where they are in close contact, such as stables and events.
Owners typically notice symptoms such as a sudden onset of fever, coughing, and nasal discharge. Early detection is crucial because the disease can lead to severe complications, especially in young, old, or immunocompromised horses. Prompt veterinary attention can help manage symptoms and prevent the spread of the virus to other horses.
What vets typically check for
- Perform a physical examination and take a detailed history of recent exposure to other horses.
- Collect nasal swabs for viral isolation or PCR testing to confirm the presence of the influenza virus.
- Conduct blood tests to assess the horse's overall health and identify any secondary infections.
- Monitor the horse's temperature and respiratory rate regularly.
- Implement supportive care, including rest, hydration, and possibly antiviral medications or antibiotics for secondary bacterial infections.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Equine influenza. Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- Comparison of Nose Wipes, Stall Sponges, and Air Samples with Nasal Secretions for the Molecular Detection of Equine Influenza Virus in Clinically and Subclinically Infected Horses.
Viruses · 2025 · United States
This study looked at different ways to detect equine influenza virus (EIV) in horses, comparing methods like nose wipes, stall sponges, and air samples to the standard method of taking nasal swabs. Researchers tested 27 horses during an outbreak, which included horses showing symptoms, those with no symptoms, and some that were not infected. They found that nose wipes and stall
- Investigation of the frequency and selected prevalence factors of equid alphaherpesvirus 4 viremia in horses with acute onset of fever and respiratory signs.
Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc · 2025 · United States
A group of horses with fever and respiratory issues were tested for equid alphaherpesvirus 4 (EqAHV4), which can cause respiratory illness. Out of 183 horses with positive nasal tests, only 25 (about 14%) also had the virus in their blood. These viremic horses were generally younger and showed more signs of swelling in their legs compared to those without the virus in their blo
- Disease progression, pathologic, and virologic findings of an equine influenza outbreak in rescue donkeys
Journal of Veterinary Internal Medicine · 2022 · GB
A group of 13 unvaccinated donkeys, aged from just a week to 12 years, showed signs of respiratory illness due to equine influenza virus. The younger donkeys had a much lower survival rate of only 16.6%, while older donkeys had a better chance of recovery at 85.7%. The illness was confirmed through various tests, and the findings highlighted the need for vaccination, especially
- pneumonia in an adult horse which had travelled in an endemic area.
The Canadian veterinary journal = La revue veterinaire canadienne · 2019
A gelding horse from eastern Canada was brought in because he had a cough and was having trouble exercising, 14 months after traveling to Vancouver Island, which is known for certain diseases. The vet diagnosed him with pneumonia using tests that looked at his cells, checked for specific germs, and used a method called PCR to identify the infection. He was treated with a medica
- First evidence of West Nile virus lineage 2 circulation in Turkey.
Veterinaria italiana · 2016 · Italy
In August 2014, a 9-year-old female horse in Turkey had to be put down after showing serious health problems, and tests revealed that she had a strain of West Nile virus (WNV) known as lineage 2 in her brain. Further analysis showed that this strain was similar to ones found in Greece between 2010 and 2012. Among other horses in the area, some had antibodies indicating they had
- Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa.
Journal of the South African Veterinary Association · 2014
Since 2007, horses in South Africa have been affected by West Nile virus (WNV), which can cause serious neurological problems. In a study of seven horses, six were infected with lineage 2 of the virus, while one was linked to lineage 1. Tests confirmed the presence of the virus in their brain tissues, and other common diseases were ruled out. The horses showed various brain iss
Frequently asked questions
- How is equine influenza transmitted?
- Equine influenza is primarily spread through respiratory droplets when an infected horse coughs or sneezes. It can also spread via contaminated equipment, clothing, or hands.
- Can equine influenza be prevented?
- Vaccination is the most effective way to prevent equine influenza. Regular vaccination schedules should be maintained, especially for horses that travel or are exposed to new horses frequently.
- What should I do if my horse is diagnosed with equine influenza?
- Isolate the affected horse to prevent the spread of the virus. Follow your veterinarian's advice for treatment and care, and ensure the horse gets plenty of rest and fluids.