Equine Herpes Virus Alert
May 13, 2011
A recent disease outbreak of Equine Herpes Myeloencephalopathy (EHV-1) has been traced to horses who attended the National Cutting Horse Associations’ Western National Championships in Odgen, Utah on April 30 – May 8, 2011. California horses who participated in this event may have been exposed to this EHV-1 virus.
The California Department of Food and Agriculture encourages owners of horses who participated in the Odgen, Utah event to monitor their horses for clinical signs of disease. A rectal temperature in excess of 102F commonly precedes other clinical signs. Therefore, we are urging owners to take temperatures on each individual horse(s) twice a day. If a temperature above 102F is detected contact your private practitioner immediately. Laboratory submission of nasal swabs and blood samples collected from the exposed horse can be utilized for virus detection and isolation.
The EHV-1 organism spreads quickly from horse to horse and the neurologic form of the virus can reach high morbidity and mortality rates. The incubation period of EHV-1 is typically 2-10 days. In horses infected with the neurologic strain of EHV-1, clinical signs may include: nasal discharge, incoordination, hind end weakness, recumbency, lethargy, urine dribbling and diminished tail tone. Prognosis depends on severity of signs and the period of recumbency. There is no specific treatment for EHV-1. Treatment may include intravenous fluids, anti-inflammatory drugs and other appropriate supportive treatment. Currently, there is no equine vaccine that has a label claim for protection against the neurological strain of the virus.
Horse-to-horse contact, aerosol transmission, and contaminated hands, equipment, tack, and feed all play a role in disease spread. However, horses with severe clinical signs of neurological EHV-1 illness are thought to have large viral loads in their blood and nasal secretions and therefore, present the greatest danger for spreading the disease. Immediate separation and isolation of identified suspect cases and implementation of appropriate biosecurity measures are key elements for disease control.