⚠️ Heads-up: Ongoing EHV-1 / EHM Outbreak — What California Horse Owners Should Know
Horse owners across the U.S. are currently dealing with a serious outbreak of Equine Herpesvirus‑1 (EHV-1) affecting horses in Texas, Louisianna, Colorado, Oklahoma, and New Mexico. The confirmed cases are linked to recent a Womens Professional Rodeo Association (WPRA) finals and barrel racing event in Texas (useventing.com). As of November 21st, there have been 16 confirmed cases associated with the event. While there are no confirmed cases in California at this time (as of the latest update Nov 19th), the California Department of Food and Agriculture (CDFA) is urging increased vigilance — especially for horses recently returned from out-of-state events or large gatherings. (apps1.cdfa.ca.gov)
🐴 What is EHV-1 / Equine Herpes Myeloencephalopathy (EHM)
- EHV-1 is a contagious virus that commonly causes respiratory disease and, in pregnant mares, can lead to abortion or neonatal foal death. (APHIS)
- In more serious cases, EHV-1 can lead to a neurological condition called EHM — which affects the brain and spinal cord and can be fatal. (CDFA)
- The virus spreads easily through nose-to-nose contact, respiratory droplets, shared equipment (tack, water/ feed buckets), contaminated surfaces, and human activity (hands, clothing, gear). (APHIS)
- Incubation is usually 2–10 days, and infected horses can shed the virus for 7–10 days — sometimes longer. (CDFA)
⚠️ Clinical Signs to Watch For
If your horse develops any of the following after exposure or recent travel — contact your veterinarian immediately:
- Fever (e.g. > 101.5 °F) (AAEP)
- Nasal discharge or cough, lethargy, loss of appetite — respiratory-disease signs (APHIS)
- Neurologic signs: incoordination or weakness (especially hind limbs), stumbling or unable to stand, loss of tail tone, urinary incontinence, recumbency. (APHIS)
- In pregnant mares: possible abortion or foal loss, sometimes without obvious warning signs. (AAEP)
✅ What Horse Owners Should Do — Especially in California
Even without confirmed local cases, it’s smart to be proactive. Recommendations from CDFA, national guidelines, and veterinarians include:
- Quarantine & monitor any horses that returned from out-of-state events (especially where outbreaks occurred) — ideally isolate them from other horses for at least 21 days. (CDFA)
- Take and record temperatures twice daily during the quarantine/monitoring period; watch closely for any respiratory or neurologic signs. (APHIS)
- Practice strict biosecurity: do not share tack, water/ feed buckets, grooming supplies, or equipment; clean and disinfect tack, barns, stalls, trailers, etc. between uses. (CDFA)
- Minimize horse-to-horse and horse-to-human contact, especially if horses are coming from events or traveling. (ceh.vetmed.ucdavis.edu)
- Avoid events or unnecessary travel with horses, if possible — or at least follow enhanced biosecurity and monitor health closely. (Dtnpf)
- Consult your veterinarian about vaccination: vaccines exist to reduce respiratory disease and abortion risks from EHV-1 (or EHV-4), but they do not protect against the neurological form (EHM). (ceh.vetmed.ucdavis.edu)
📝 Bottom line for horse owners in our area
Even if there are no confirmed EHV-1/EHM cases currently in California or Ventura county, the ongoing multi-state outbreak means the risk exists, especially for horses traveling in and out of the state. If you own/manage an equine facility with horses traveling to events, now is the time to review and tighten your barn’s biosecurity protocols. It is recommended that horses receive the EHV-1 and 4 vaccination every 6 months when in large barns. If any horse shows fever, respiratory or neurologic symptoms — contact your veterinarian immediately and avoid moving horses until cleared. Prevention and early detection are key.