🐴 Viral Respiratory Disease in Horses: Risk Management & Vaccines in 2025 💨🧠

By Dr Duncan Houston BVSc

Viral respiratory disease is a major concern in the horse industry—especially at shows, sales, and clinics where horses from many different locations come together. In 2025, strategic vaccination and good management practices are more important than ever to prevent the spread of equine influenza, equine herpesvirus 1 (EHV-1), and EHV-4. 🧪🐎

💨 The Main Viruses Behind Respiratory Disease

• 🦠 Equine Influenza: Highly contagious respiratory virus causing fever, cough, and nasal discharge
• 🧬 EHV-1: Can cause respiratory disease, abortion, and neurological disease
• 🧬 EHV-4: Primarily respiratory, less commonly leads to complications

In the past, EHV infections were often called “rhino” or “rhinopneumonitis.” That term has been retired, since rhinoviruses are distinct from herpesviruses. 🧠

📈 Why Horse Shows Pose a Risk

At shows or large gatherings, horses:

• 🚛 Are mixed from different farms and health backgrounds
• 🤧 Shed viruses in their nasal secretions
• 📉 Experience stress, lowering immune defenses

In a study conducted by veterinarians at Colorado State University, researchers found that all three viruses—influenza, EHV-1, and EHV-4—were being shed at each of the four horse shows they tested. 🧪

📊 What the Study Found

• 📍 Viral shedding occurred at all tested events—even without full outbreaks
• 📈 Most shedders were under 2 years of age
• 📉 Only one show had confirmed flu-related illness

This indicates that young horses often carry and spread viruses even when not showing symptoms. 🧬

💉 Vaccination: Still the Best Prevention

Vaccinating for:

• 💉 Equine influenza
• 💉 EHV-1
• 💉 EHV-4

…is still the best way to reduce risk. While vaccines do not offer 100% protection, they help reduce virus shedding and illness severity. 🔒

🧠 Important Note on Neurological Herpes

Although EHV-1 can mutate and cause neurological disease (equine herpesvirus myeloencephalopathy, or EHM), no licensed vaccine currently prevents this form. However, vaccination still reduces respiratory shedding and can slow outbreaks. ⚠️

📅 Vaccine Recommendations for Show Horses

• 📆 Administer at least 2 weeks prior to travel
• 📋 Boosters every 6 months for high-risk horses
• 🧬 Inquire about flu/rhino combination vaccines

🧼 Biosecurity Tips for Events

• 🧴 Bring your own buckets and grooming tools
• 📍 Avoid nose-to-nose contact with unfamiliar horses
• 📱 Monitor temperature daily after returning home
• 🛏️ Quarantine new or returning horses for 7–10 days

📲 Ask A Vet for Show Season Planning

Heading to a show or managing a barn with travel horses? Visit AskAVet.com or use the Ask A Vet App to build a customized vaccination and quarantine plan. 📱🐴

Dr Duncan Houston and the team can help you time boosters, identify high-risk animals, and avoid unnecessary outbreaks this season. 💬🧠

🏁 Final Thoughts

Viral respiratory disease remains a top concern for horse owners. In 2025, proactive vaccination, smart travel practices, and awareness of young horse vulnerability make a big difference. Your horse may look healthy—but they could still be shedding. Protect your barn. ❤️🐎

Need a respiratory health plan? Visit AskAVet.com to prepare for your next horse show 🐴💉