The EDCC is the best place for owners to find an updated list of infected horses. | Adobe StockRecent reports of an outbreak of equine herpesvirus- 1 (EHV-1) and its neurologic form, equine herpes myeloencephalopathy (EHM), have prompted many horse owners to look for clear, accurate information about the disease and what it means for their horses. While cases have been confirmed in seven states, as reported on Nov. 22 by the Equine Disease Communication Center (EDCC), veterinary experts emphasize this virus is well-studied, familiar to equine practitioners, and manageable with established biosecurity practices. We spoke with Ben Buchanan, DVM, Dipl. ACVIM, ACVECC, of Brazos Valley Equine Hospitals in Navasota, Texas, to answer common questions and bust common myths and misconceptions about the outbreak.HP: What do we know so far about this outbreak? How many horses are affected and where cases have been confirmed?BB: The EDCC publishes the overall numbers of confirmed reported cases; however, there can be a bit of a lag time from the time a horse is infected to publication with the EDCC based on how quickly the cases are reported. The Texas Veterinary Medical Diagnostic Laboratory also has a dashboard of cases that test positive at the state lab. The EDCC is the best place for horse owners to find an updated list of overall numbers. We know that there were about 1,000 horses at the show in Waco and two-thirds of those were from Texas. In the seven to 10 days prior to the first case being reported, some of these horses attended other events and mingled with other animals. The reports circulating of 25+ or more equine deaths with at least 200 exposed are inaccurate.HP: How does EHV typically spread between horses, and what do current findings tell us about transmission in this event?BB: Equine herpesvirus is spread through the horses mucus droplets. It can be spread on shared items that have touched the horses mouth or nose such as lead ropes and bits, through close contact between horses, shared water (water buckets and in hoses), and by humans that have been in contact with an infected horse. In perfect conditions in water, EHV can survive up to two weeks and up to two days in the environment.HP: What are veterinarians recommending in terms of quarantine or biosecurity for barns in affected or neighboring regions?BB: The best thing owners can do is limit the spread of mucus between horses. The rule of thumb is to keep 30 feet between your horse and unknown horses, but 60 feet is even better. Do not share equipment with other barns or between infected and noninfected horses and practice good hygiene such as frequent hand washing.Authorities recommend a quarantine length of 21-28 days, which allows the horse to go through one complete life cycle of the virus. The only way to know if your horse has the virus is through testing (see below). At this time the state of Texas put a 21-day hold on horses who were at the WPRA event in Waco, which means horses should stay at their home farm. This means that without fever, respiratory problems, or neurologic signs, the horses will be cleared on Dec. 2. If more horses develop clinical signs, this timeline could be extended or become a full quarantine.HP: Is there any evidence this outbreak represents a new strain or shows unusual behavior compared to previous EHV cases?BB: Nothing about this strain is new or makes it more deadly. There are nine different identified equine herpesviruses. This disease is caused by EHV-1. There are different strains of EHV-1 with a single amino acid difference between neuropathic and non-neuropathic EHV. All forms of EHV-1 can cause respiratory, neurologic, and reproductive clinical signs. Nothing is new about this virus. EHV is frequently shed in fall, winter, and spring, which is when we see outbreaks.HP: What are the most common misconceptions or sources of panic youre seeing, and what does the science say in response?BB: There is quite a bit of panic circulating online. Veterinarians have a good handle on the epidemiology of EHV, how outbreaks happen, and how to handle the aftermath. Following veterinarian guidelines is the best way for owners to keep their horses safe. The truth is very few horses die from this disease. During an outbreak in 2011, there were 400+ exposed horses cases of EHV (likely more) and only 13 horses died. Most horses who get sick are able to recover, especially if they have been vaccinated against the disease. The vaccination reduces the circulation of the virus in the horses body if they are infected and reduces viral shedding, meaning less risk to the population.HP: What immediate steps can barns take to keep operations running smoothly while limiting spread?BB: Isolate sick horses. Avoid mixing of exposed and nonexposed horses, including tack and water. Practice a very high level of biosecurity and monitor rectal temperatures.HP: How long does it typically take for an outbreak to resolve, and what markers do vets watch for to declare it contained?BB: This is based on decisions made at the state level. The state and federal regulatory veterinarians determine when an outbreak is contained or resolved. The protocol of the 21-day hold is to help them gather info about how far the disease has spread and make recommendations to veterinarians and horse owners on next steps.HP: What final message would you give horse owners who are hearing conflicting information and feeling anxious about this situation?BB: Monitor your horse daily and take temperatures frequently. If your horse does not show signs of infection, there likely isnt a reason to test your horse for EHV. If your horse has been exposed, quarantine him and contact your veterinarian for guidance.Editors note: See details about testing horses for EHV in this post from Buchanan.