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Kansas Animal Health Commissioner Justin Smith says strong biosecurity practices are critical to slowing the spread of Equine Herpesvirus-1, a highly contagious disease that can cause respiratory illness, abortion, and severe neurological damage in horses.

EHV-1 is found worldwide, but a recent outbreak in the United States has now reached at least seven states, including Texas, Oklahoma, Wyoming, Colorado, New Mexico, Pennsylvania, and Arizona. Smith notes that the first sign of the current spread emerged after a major national event in Texas, prompting some states to add new restrictions on horse shows or cancel events altogether.

The neurological form of the virus, Equine Herpes Myeloencephalopathy, occurs when blood vessels in the brain and spinal cord are damaged. Symptoms can include hind limb weakness, difficulty walking or standing, trouble urinating, lethargy, fever, and nasal discharge. The mortality rate for EHM is estimated between 30% and 50%.

Vaccines can reduce the risk of EHV-1 but are not consistently effective against EHM. Smith advises horse owners to follow key biosecurity steps, such as isolating exposed or returning horses for 14 days, monitoring temperatures twice daily, keeping vaccinations current, disinfecting equipment, limiting horse-to-horse contact, changing clothes and boots after events, and checking state requirements before traveling. The Equine Disease Communication Center provides updated information on EHV-1 and EHM. Suspected cases in Kansas should be reported to the Kansas Department of Agriculture’s Division of Animal Health at 785-564-6601.