According to the Oregon Department of Agriculture and Oregon State University's Lois Bates Acheson Veterinary Teaching Hospital, a horse in Marion County has been diagnosed with the neurologic form of EHV-1, equine herpes virus, "a naturally occurring virus that can cause serious illness in horses when activated."
Thus far there is no indication the virus has spread. Horses from the same property as the sick horse traveled to an event at the Oregon Horse Center in Eugene and OSU recommends horses that attended the event have their temperatures monitored. According to the Oregon Department of Agriculture press release:
One Marion county horse has been hospitalized after testing positive for the neurological form of Equine Herpes Virus (EHV-1). The horse, which has been treated at Oregon State University’s College of Veterinary Medicine’s Large Animal Hospital, began showing acute neurologic signs on April 28 and was immediately referred to OSU. The positive EHV-1 diagnosis was made April 29. All horses at the Marion County property have been quarantined.
The Oregon Department of Agriculture reports there is no indication at this time that the virus has spread to other horses beyond those being quarantined. Preliminary epidemiological investigations are underway. In all, there are 20 horses at the Marion County stable. The stable owner and all horse owners have been very cooperative and supportive of the disease control actions taken.
The investigation shows that horses from the affected property have attended recent events held at the Linn County Fairgrounds in Albany on April 16-19, and the Oregon Horse Center in Eugene on April 25-26. While the risk to these horses appears to be low at this time, concerned horse owners are advised to contact their veterinarian.
The OSU vet hospital also issued a press release on the issue with facts on EHV-1. OSU says that this is not the mutated form of the virus but it can still have "serious consequences." OSU suggests checking out the American Association of Equine Practitioners for more information.
No other horses that attended these events have shown clinical signs of EHV-1. Owners of horses that attended these events are encouraged to monitor their horses for any signs of respiratory or neurologic disease. EHV-1 is not transmissible to people.
“This is not the neurotropic or mutated form of the virus, which can really cause problems,” said John Schlipf, a large animal internal medicine specialist with the OSU College of Veterinary Medicine. “This form of EHV-1 can still have serious consequences.”
Schlipf said that clinical signs of the neurologic form of EHV-1 often begin with the hind limbs and include:
Uncoordinated, stumbling movements;
An unusual gait;
A weak tail tone;
Difficulty urinating, and dribbling of urine;
Nasal discharge, frequently accompanied by a fever.
The Oregon Department of Agriculture recommends horses that attended the Albany or Eugene events avoid contact with other horses and have their temperatures monitored twice daily. Temperatures over 101.5 degrees may indicate illness.
Horses with signs listed above should be isolated from other animals, and owners should contact their veterinarians immediately. EHV-1 can also affect alpacas and llamas, Schlipf said.
EHV-1 can cause abortions in animals, thus pregnant mares should not co-mingle with horses returning from those shows.
“Horse owners should be aware that although EHV-1 is not transmissible to humans, people can spread the virus on their hands and clothing if in contact with an infected horse,” Schlipf said.