Equine owners need to continue to be vigilant and aware of the risk of equine herpesvirus-1 (EHV-1) to their animals, cautions the Indiana Board of Animal Health (BOAH). Numerous cases of illness and death stemming from EHV-1 have been diagnosed across the county this year. The virus is active and transmissible year-round, so the need to maintain good biosecurity and watch for clinical signs never stops.
Last week, a 3.5-year-old standardbred filly displaying neurologic signs was confirmed test-positive for equine herpesvirus-1. The horse was euthanized. All exposed horses on the premises in Shelby County have been quarantined and are being monitored twice daily for fever and other clinical signs. Horses on an additional, related premises in Madison County have been quarantined and are also being monitored for fever and clinical signs. An epidemiological investigation has revealed that the infected horse had no recent direct contact with other horses or people outside of the two involved premises. Indiana State Board of Animal Health (BOAH) officials will continue to monitor the situation.
As a reminder: EHV-1 diagnosed in a horse with neurologic signs, referred to as EHM (equine herpesvirus myeloencephalopathy), is reportable to the Indiana State Board of Animal Health. (https://bit.ly/3uEzZev). Laboratory results should be forwarded to BOAH right away.
When a case is confirmed via laboratory test, the attending veterinarian should contact a BOAH district veterinarian to report the diagnosis and help manage the situation. Barns with infected horses need to be quarantined. Exposed horses need to have their temperature monitored twice daily for a time period after their last exposure, depending on the details of the particular incident. The need for additional testing will be determined by the clinical condition of the remaining horses, and they should be observed carefully for clinical signs of disease.
Testing horses for EHV-1 may be done with several different tests at the Animal Disease Diagnostic Laboratory (ADDL) at Purdue or other approved laboratories. PCR testing on a nasal swab and nonclotted (purple top) blood have been the most successful at identifying potential cases. Interpretation of test results are dependent on several factors, including clinical signs in the animal, previous cases, and temperature changes in the horse.
To report and coordinate response from a BOAH district veterinarian, contact Dr. Jennifer Strasser, equine programs director, at jstrasser@boah.in.gov or 317-544-2400.
BOAH's goal is to avoid widespread cases of EHV-1/EHM, especially when horses are commingled for events. An important step is for horse owners to respect a self-imposed quarantine on clinical horses until the laboratory test results are returned. Restricting movement and contact with others early in the course of disease is imperative in preventing spread of this disease.
EHV-1 is common in the horse population. The most common clinical manifestation is a mild respiratory illness, especially in young horses, often called equine rhinopneumonitits. Less commonly, EHV-1 manifests itself as a neurologic form known as EHM. In very rare cases, EHM may be caused by EHV-4. Potential signs of EHM include: decreased coordination, urine dribbling, fever, hind limb weakness, leaning against things to maintain balance, loss of tail tone, lethargy, and the inability to get off the ground. More-detailed information about the disease is available online: https://bit.ly/3FGZ1Qu.
Equine owners should exercise go biosecurity when traveling and interacting with other horses at show venues, race tracks, and boarding facilities. Tack, water buckets and other equipment can spread the virus between animals, so regular cleaning and disinfection are necessary, in addition to avoiding sharing. As always, vaccination is important to keeping horses healthy and supporting good immunity.
Categories: Indiana, Livestock