Can valacyclovir and heparin help horses survive EHV-1 and its severe neurologic form, equine herpesvirus myeloencephalopathy? A newly published Virginia Tech study found that horses treated with this antiviral and anticoagulant combination had a lower incidence of EHM and better survival during naturally occurring EHV-1 outbreaks. All horses that received the combination therapy survived, including several horses affected by EHM that later returned to work.¹ Researchers reviewed 111 horses naturally exposed to EHV-1. Twenty-two horses were confirmed positive, and nine developed EHM. Four infected horses that did not receive valacyclovir or heparin developed grade 5 out of 5 ataxia and were euthanized. In comparison, every horse treated with the combination survived.¹ These findings are extremely promising, but this was a small, retrospective outbreak study—not proof of a guaranteed cure. The horses were not randomly assigned to treatment groups, and additional controlled research is needed. In this video, we explain: • What EHV-1 and EHM are • The difference between EHV-1 infection and neurologic EHM • How valacyclovir may help limit viral replication • Why heparin may help protect blood flow to neurologic tissue • What the Virginia Tech researchers discovered • The study’s important limitations • Early EHV-1 and EHM warning signs • What horse owners should do during a suspected outbreak Valacyclovir is an antiviral medication, while heparin is an anticoagulant. Researchers believe the medications may work together by limiting viral activity and reducing harmful clot formation associated with vascular injury. These are prescription medications that require veterinary diagnosis, dosing, supervision, and monitoring. Never administer valacyclovir, heparin, or another prescription medication without direct veterinary guidance. Heparin can cause serious bleeding complications when used incorrectly. Early EHV-1 signs may include fever, nasal discharge, depression, reduced appetite, and limb swelling. Neurologic signs can include toe dragging, stumbling, hind-limb weakness, urine dribbling, tail weakness, leaning, difficulty standing, or an inability to rise. If your horse develops a fever or neurologic abnormalities, isolate the horse and contact your veterinarian immediately. Do not force a neurologically impaired horse to walk. CHAPTERS 00:00 A possible breakthrough for EHM 00:49 Why EHM is so feared 01:52 Inside the new Virginia Tech study 03:05 What happened to the treated horses 04:22 Valacyclovir’s possible role 05:12 Why researchers included heparin 06:18 What the results do—and do not—prove 07:28 Early EHV-1 and EHM warning signs 08:35 What to do during a suspected outbreak 09:32 What this research means for horses FOOTNOTES 1. Megan Marchitello, Krista Estell, Elsa K. Ludwig, Abby M. Sage, and Nathaniel A. White, “Combined Treatment with Valacyclovir and Heparin Reduced the Incidence of Equine Herpesvirus Myeloencephalopathy and Improved Survival in Naturally Occurring Equine Herpesvirus-1 Outbreaks,” Journal of the American Veterinary Medical Association, published online July 10, 2026, 1–6, https://doi.org/10.2460/javma.26.02.0118. 2. United States Department of Agriculture, Animal and Plant Health Inspection Service, “Disease Alert: Equine Herpesvirus,” accessed August 2, 2026, https://www.aphis.usda.gov/livestock-poultry-disease/equine/herpesvirus. 3. American Association of Equine Practitioners, Equine Herpesvirus Myeloencephalopathy Incident Response Guidelines for State Animal Health Officials, November 2025, https://aaep.org/wp-content/uploads/2018/01/EHM-Guidance-Document-FINAL-20251103.pdf. This video is for educational purposes and is not a substitute for veterinary diagnosis or treatment. #EHV1 #EHM #EquineHealth This video is for educational purposes and constitutes Fair Use under Section 107 of the US Copyright Act of 1976. Allowance is made for “Fair Use” for purposes of education, research, criticism, comment, and news reporting. This video is fully transformative and created in accordance with YouTube’s Content Reuse Policy under the Content Reuse Act. It includes original narration, commentary, educational context, visual edits, and added value through storytelling and analysis. No content is simply re-uploaded. #horse #horses #horsecare #horsenews #equestrian
