Assistant State Veterinarian
Late last week, the Department of Agriculture was notified of one laboratory-verified case of Equine Herpesvirus Myeloencephalopathy, or EHV-1 wildtype, in Washington.
EHV-1 is a highly contagious virus that can be fatal to horses. The disease is spread from horse to horse through direct contact, on feed, tack and equipment. While people are not made sick by the virus, they can carry the virus on their clothes or hands. Horse owners should carefully wash their hands and equipment to prevent the spread of the virus.
WSDA is not currently establishing any quarantine, but our field veterinarians are actively tracing all areas where the infected horse might have contacted other animals. Given the high risk of contamination, here are additional recommendations for horse owners.
Watch for symptoms
Closely observe your horse and look for signs of possible infection, which include:
• Fever of 102.5 degrees F or higher
• Discharge from eyes or nose
• Limb edema or swelling
• Spontaneous abortions
• Neurologic signs such as an unsteady gait, weakness, urine dribbling, lack of tail tone and recumbency.
Be sure to obtain and record the body temperatures of all horses on the premises twice a day, ideally first thing in the morning and last thing at night, and always before administering medications since some can decrease body temperature.
Let your veterinarian know if you detect a fever or notice any of the other symptoms listed. The veterinarian may want to take nasal swabs or blood samples to test for EHV-1.
EHV-1 testing at WSU
Suspected cases should be checked for both West Nile Virus and EHV1 by a veterinarian. The Washington Animal Disease Diagnostic Laboratory in Pullman is providing testing.
Veterinarians should contact WADDL at 509-335-9696 to submit a red top and lavender top tube with nasal swabs directly to Dr. Jim Everman or Dr. Kevin Snekvik at WADDL.
Vaccines
It’s not too late to vaccinate your horse against EHV and there are a number of vaccines available.
Several EHV-1 vaccines available in North America carry a label claim for the control of respiratory disease induced by EHV-1 and EHV-4. These are multi-component inactivated vaccines specifically, Prestige® (Merck), Calvenza® (Boehringer Ingelheim Vetmedica) and Fluvac Innovator® (Zoetis) and the modified live vaccine Rhinomune® (Boehringer Ingelheim Vetmedica).
There are also two EHV-1 vaccines licensed for the control of abortion and respiratory disease. These vaccines are single-component inactivated vaccines, namely Pneumabort-K® (Zoetis) and Prodigy® (Merck).
Biosecurity – steps to protect your horse and others
To protect your horse from becoming infected, and help limit the potential spread of this virus, there are several things all horse owners should be doing.
1. Monitor all horses on your premises.
2. Limit direct horse-to-horse contact.
3. Limit stress to horses.
4. Don’t share equipment.
5. Clean barn areas, stables, trailers, or other equine contact surfaces thoroughly, removing all organic matter (dirt, nasal secretions, uneaten feed, manure, etc.) before applying a disinfectant. Organic material decreases the effectiveness of any disinfectant, especially if 10% bleach is used.
6. Use footwear disinfectant and hand sanitizer where indicated.
7. If you have a potentially exposed horse, restrict human, pet and vehicle traffic from the area where the exposed horse is stabled.
8. Clean all shared equipment and shared areas, again removing dirt and manure before application of a disinfectant.
9. Self-quarantine animals with questionable sysmptoms.
10. If you have mules, isolate them from horses since recent studies suggest mules can be silent carriers of the virus.
The time of exposure to illness of EHV-1 is typically two to 14 days. By self-quarantining animals with questionable symptoms, vaccinating horses for EHV-1 and West Nile virus, and practicing good biosecurity on the farm and during travel, horse owners can do a lot to help prevent further spread of the virus.
We’ll be sure to provide any updates here on the AgBriefs blog.