AlpacaGram 12.63 | Understanding the Recent EHV Outbreak

Keeping Your Herd Safe: Understanding the Recent EHV Outbreak

As many of you know, a recent outbreak of Equine Herpes Virus (EHV) and Equine Herpes Myeloencephalopathy (EHM) has been linked to horses that participated in, or were present at, barrel racing and rodeo events in Texas and Oklahoma. EHV is a common DNA virus found in horse populations worldwide. The two most common strains are EHV-1, which can cause abortion, respiratory disease, and neurological disease; and EHV-4, which primarily causes respiratory disease but can occasionally lead to abortion and, rarely, neurological disease. EHM is the neurological form of EHV. It is highly contagious and can have a mortality rate as high as 30%.

EHV spreads most often through direct contact with nasal discharge or aerosol droplets. Infected horses—and other equids such as donkeys—may not show clinical signs but can still act as carriers. Horses can also contract the virus through contaminated surfaces, including stalls, water, feed, tack, and transport vehicles. People can inadvertently spread the virus through contaminated hands and clothing.

Camelids can contract EHV from infected horses, although confirmed cases are rare, and no published cases have been reported in decades. When illness does occur in camelids, signs may include weakness, incoordination, and blindness. Symptoms typically develop within 30 days of exposure. There is no vaccine for the neurological form of the disease in horses, and no vaccines for any EHV strains are labeled for camelids. Some equine vaccines may be administered to camelids, but veterinary guidance is strongly recommended before doing so.

Biosecurity remains essential. Minimize contact with horses that travel, or with animals that interact with traveling horses, for at least 30 days. Avoid exposing alpacas or llamas to any items that have been in contact with traveling horses or barns that house them. Maintain strong hygiene practices, including handwashing and footbaths, if contact with horses cannot be avoided. If you have concerns about possible exposure, please consult your veterinarian.