Spring Signals a Rise in Equine Influenza: What Horse Owners Need to Know!

As we bid farewell to winter and welcome the vibrant days of spring, horse owners and barn managers are urged to stay vigilant against equine influenza (EIV), a highly contagious respiratory disease that tends to spike during this time of year. Recent data from the Equine Biosurveillance Program indicates a clear seasonal pattern, reinforcing the urgent need for proactive disease prevention and biosecurity measures.

According to the latest analysis from the program, conducted in collaboration with Merck Animal Health and the University of California, Davis, equine influenza ranks among the most commonly diagnosed respiratory diseases affecting equines. It is grouped with equine herpesvirus type 4 (EHV-4) and Streptococcus equi subspecies equi (strangles) — the “big three” respiratory pathogens causing concern for horse health.

Dr. Duane E. Chappell from Merck Animal Health explains, “Every year, we see an uptick in equine influenza cases as horses begin traveling for competitions and training in the spring.” The virus spreads rapidly through physical contact between horses, shared equipment, and even through human handlers who may inadvertently carry the virus.

Who is at Risk?

Traveling horses are particularly susceptible to EIV. The latest program update reveals that 58% of horses diagnosed with EIV had traveled recently, with show horses making up 42% of reported cases. Young horses, those under travel-related stress, and those in crowded environments like competitions are especially at risk for an outbreak.

“Vaccination remains the best line of defense against severe illness,” Dr. Chappell adds. Common symptoms of equine flu can manifest suddenly, and include high fever (often exceeding 102°F), dry cough, nasal discharge, lethargy, and loss of appetite.

In the event of suspected equine influenza, immediate isolation of the infected horse is crucial. “It’s essential to separate symptomatic horses from others and adhere to strict biosecurity protocols,” emphasizes Dr. Chappell. Many upper respiratory conditions can exhibit similar symptoms, so consulting a veterinarian for diagnostic tests and care recommendations is vital.

How to Prevent Spring Outbreaks

With the seasonal spike in equine flu cases, veterinarians stress the importance of taking preventative measures. Here are some key strategies for horse owners:

1. Vaccination: Ensure that your horses are up-to-date on their influenza vaccinations, especially those who travel frequently. Consider vaccinating resident horses that may come into contact with transient horses, particularly older horses with weaker immune systems.

2. Biosecurity: Limit direct contact with unfamiliar horses, and refrain from sharing tack, water buckets, or grooming tools, as these can be pathways for the virus.

3. Monitoring and Quarantine: New arrivals or horses returning from events should be monitored for at least two weeks before integrating them fully into the herd. Daily temperature checks during travel can help catch early signs of disease.

4. Hygiene Practices: Handlers should maintain good hygiene by washing hands (or using hand sanitizer) and regularly disinfecting equipment to prevent the spread of germs.

“Influenza is a serious but preventable disease,” Dr. Chappell declares. By remaining attentive to vaccination schedules and implementing robust biosecurity practices, horse owners can dramatically reduce the risk of outbreaks and ensure the health of their herds this season.

Don’t hesitate to speak to your veterinarian about tailored vaccination strategies to best protect your equine companions. For ongoing updates on equine flu and to access the regional disease threat map, stay connected with the Equine Respiratory Biosurveillance Program. Your horse's health could depend on it!