EVA Outbreak and Vaccine Shortage Affecting Western U.S.

An outbreak of equine viral arteritis (EVA) has resulted in quarantine restrictions in 18 states, with nine states reporting positive cases. A vaccine shortage is hampering efforts to control the outbreak.

 Although the virus has thus far been limited to Quarter Horse breeding farms, Peter Timoney, FRCVS, PhD, of the University of Kentucky's Maxwell H. Gluck Equine Research Center, sees an opportunity for transmission into the Thoroughbred industry as the breeds often share the same areas at tracks and are often crossbred.


"Strains of the virus active at this time are clearly abortogenic," said Timoney. "People need to be very careful before they haul horses to racetracks, sales, shows, and breeding farms. New arrivals on breeding farms must be isolated at least three weeks before coming into contact with any other horses, but especially mares in foal."


While there is a vaccine to protect against EVA, the outbreak has caused a severe shortage. No doses will be available until October, according to Rocky Bigbie, DVM, MS, director of field veterinary services for Fort Dodge Animal Health, the vaccine manufacturer.


New Mexico Deputy State Veterinarian Dave Fly, DVM, said vets within that state are not writing health certificates more than seven days before they will be needed for general hauling, and no more than 48 hours before the horse goes to a track. No other states have imposed restrictions at this time.


Kentucky has not imposed any restrictions, but Rusty Ford of the Kentucky State Veterinarian's office says they are taking special interest in horses coming from affected states.


EVA is a contagious viral equine disease that closed the breeding industry in Kentucky in 1984. Some of the clinical signs associated with EVA are fever, respiratory illness, ocular inflammation, dependent edema (swelling), pneumonia or pneumonia enteritis in foals, and abortion. The virus can be spread through semen in the case of an acutely infected stallion, infected respiratory secretions, or indirectly through shared breeding shed equipment or tack.


Stallion owners are urged to test their stallions and vaccinate as soon as the vaccine become available. Seropositive shedding, or carrier, stallions should be managed separately from non-shedding seropositive and seronegative stallions, and test semen from all seropositive stallions to ensure they are not carriers.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care. She owns a portly gray gelding named Duncan and dabbles in several equestrian disciplines, with an emphasis on dressage.

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