11/21/2025
🚨 Equine Herpes Virus Update (EHV-1/EHM) – specifically EHM...Equine Herpes Myeloencephalopathy (Neurologic strain)🚨
The Arizona State Veterinarian has confirmed an EHV-1/EHM outbreak linked to a recent barrel racing event in Waco, TX (Nov 5–9). This particular strain is highly virulent, has caused neurologic disease, and has shown a high mortality rate in affected horses. As of today, no confirmed cases in Arizona. I will keep you updated as new information arises. Please don't panic because of social media.
Because many horses have already dispersed back to their home states—including Arizona—the next 10–14 days are critical for monitoring.
🐎What to Know About EHV-1:
• Horses may incubate the virus for 2–14 days, typically showing fever first, followed by neurologic signs.
• Horses infected at an event may appear normal traveling home but can become contagious and sick after returning.
• Fever of unknown origin is often the earliest indicator—temp >101.5°F
🏇 Recommendations :
• Use caution when traveling, hauling, or attending shows, ropings, rodeos, or group events for the next 2-3 weeks
• Any horse returning from a rodeo event in the last week should be isolated for several days, with temperatures checked twice daily.
• Horses showing fever, neurologic signs, or “just not right” should be quarantined and evaluated immediately.
• Event organizers are being asked to strengthen biosecurity—limit horse movement, regulate warm-up areas, and enforce cleaning and disinfection.
💉 Vaccination Matters:
While no vaccine completely prevents EHV-1, horses with current flu/rhino vaccinations may have stronger immune responses and reduced risk of severe disease.
✔️We do recommend current vaccines
👍🏼Biosecurity Is Your Best Defense:
New horses or horses attending rodeo events in last 2 weeks should be quarantined for 2 weeks and temperatures monitored
Dr Hulse will keep our equine community updated as more information becomes available from the Arizona State Veterinarian 🐎💜
— West Valley Equine Veterinary Services
