Colorado animal health officials are investigating an equine neurologic case in the Greeley area after a horse attended an event and became ill.

The State Veterinarian’s Office has been collaborating with the CSU Veterinary Teaching Hospital and Veterinary Diagnostic Laboratory, the Colorado Horse Park, and private practicing veterinarians involved in the case.  

The horse was on site for an event at the Colorado Horse Park from June 22 until June 25, 2022 before returning to its home in Weld County. Two days after returning home, the horse began displaying neurologic signs consistent with Equine Herpes Myeloencephalopathy, a disease caused by EHV-1 virus.

CSU Veterinary Diagnostic Laboratory completed the initial diagnostics which were inconclusive. Follow-up diagnostics showed a low viral load of EHV-1 on one nasal swab. Two whole blood samples, as well as one CSF sample, were negative for EHV. The horse remains hospitalized at CSU VTH with continued supportive therapy.  

"Equine Herpes Myeloencephalopathy cases can be challenging to diagnose, as EHV is a ubiquitous virus in the equine population," said Dr. Maggie Baldwin, Colorado State Veterinarian "This case is clinically compatible with EHM, although we do not have confirmatory tests to completely support the diagnosis at this time,

"As with any equine event, there is risk for stressed horses to begin shedding the virus and pose a risk to other horses on site," she said. "Out of an abundance of caution, we recommend that any horses at the event or on site at the Colorado Horse Park be monitored for the next two weeks."

Because the horse was removed from the premises prior to the onset of clinical signs, the risk of exposure to horses at the horse park is low. However, as EHV is a ubiquitous virus and commonly present in the environment, biosecurity measures are paramount to decreasing potential for disease transmission.

Horse owners and attendees at the Colorado Horse Park should monitor their horses with twice daily temperatures and for EHM-compatible clinical signs. If fevers or neurologic signs are noticed, please contact your veterinarian who will consult with the State Veterinarian's Office.

The Colorado Horse Park is not currently under quarantine, but will continue to work closely with event veterinarians and the State Veterinarian’s Office. The park will continue to monitor the situation and implement enhanced biosecurity practices, including the routine monitoring of twice daily temperatures. If elevated temperatures or clinical signs are noticed while on site at the Colorado Horse Park, please contact show management and the horse show veterinarian.  

About the virus

Infected horses may not show clinical signs of the virus but may still act as carriers. EHV‐1 is spread from horse to horse through contact with nasal discharge or spread as aerosol droplets. Horses can also contract the virus by coming into contact with contaminated surfaces such as stalls, water, feed, tack, and transport vehicles. Humans can spread the virus from horse to horse by contaminated hands and clothing.

It is important for owners to watch for signs and symptoms and practice biosecurity measures. Good biosecurity practices include extensive cleaning and disinfection of surfaces and equipment that come in contact with affected horses, and individuals who treat or come into contact with infected horses need to follow appropriate disinfection protocols when handling multiple horses.

Veterinarians are asked to immediately report any suggestive signs of reportable diseases, even if the disease has not been confirmed.

Visit the CDA website to see the Reportable Disease List or click here to view the list as a PDF. 

The Colorado Department of Agriculture State Veterinarian’s Office may be reached any time at 303-869-9130.

Source: Colorado Department of Agriculture, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.