The Texas Animal Health Commission (TAHC) is investigating two confirmed cases of the equine herpesvirus (EHV-1) in horses at two different stables in Northwestern Galveston County. Laboratory tests conducted on nasal swabs were positive for the neuropathogenic strain of EHV-1. There is no indication of involvement of horses outside of those stabled at the two facilities.
The first confirmed horse showed signs of respiratory illness on Jan. 24, and veterinary care was sought. Prior to death some changes in behavior were present, but the usual neurologic symptoms associated with EHV-1 had not developed. The second horse that tested positive for EHV-1 showed a fever and respiratory symptoms and is under close veterinary care. Both stables have been placed under quarantine, and investigation continues.
Direct horse-to-horse contact is a common route of transmission of the virus, but indirect transmission is also important. This occurs when infectious materials (nasal secretions, fluids from abortions, etc.) are carried between infected and non-infected horses by people or inanimate objects such as buckets, tack, trailers, etc. Aerosol transmission can also occur when infectious droplets are inhaled. The source of infectious droplets is most often respiratory secretions.
Symptoms of EHV-1 include fever, which is one of the most common clinical signs and often precedes the development of other signs. Respiratory signs include coughing and nasal discharge. Neurologic signs associated with EHV-1 are highly variable, but often the hindquarters are most severely affected. Horses with EHV-1 may appear weak and uncoordinated. Urine dribbling and loss of tail tone may also be seen. Severely affected horses may become unable to rise.
It is important to remember that none of these signs are specific to EHV-1, and diagnostic testing is required to confirm EHV-1 infection. Many horses exposed to EHV-1 never develop clinical signs. If you suspect your horse has been exposed to EHV-1, contact your veterinarian. In general, exposed horses should be isolated and have their temperatures monitored twice daily. If an exposed horse develops a fever or other signs consistent with EHV-1, diagnostic testing may be performed. Always practice effective biosecurity before, during and after equine events and when introducing new horses to a premises.
For more information on protecting your livestock from EHV-1, contact your local TAHC regional office, call 1-800-550-8242 or visit