Equine Viral Arteritis (EVA) 



EVA is an infectious viral disease of horses that causes a variety of cHnical 

 symptoms — most significantly abortions. The disease is transmitted through 

 both the respiratory and reproductive systems. Many horses with the disease are 

 asymptomatic, and others exhibit tlulike symptoms for short periods, hi mares, 

 abortions are among the first, and in some cases, only signs of the disease. EVA has 

 been confirmed in a variety of horse breeds, and the highest infection rate is found 

 in adult standardbreds. 



Breeders, racehorse owners, and owners of show horses all have strong economic 

 reasons to prevent and control this disease. Although it does not kill mature horses, 

 EVA can virtually eliminate an entire breeding season by causing a high percentage 

 of mares to abort. In addition, U.S. horses that test positive for EVA antibodies and 

 horse semen fi"om EVA-infected horses can be barred from entering foreign countries. 

 As the horse industry becomes increasingly internationalized, nearly all major horse- 

 breeding countries are enforcing import policy measures to reduce the risk of EVA. 



Transmission 



EVA is primarily a respiratory disease. Healthy horses can inhale particles in the 

 nasal discharges from acutely infected horses during movements at sales, shows, and 

 racetracks. Because horses are herd animals that tend to commingle, this close contact 

 facilitates the spread of the virus. 



EVA can also be transmitted venereal!)' during breeding — either naturally or by 

 artificial insemination. Wlien a mare, gelding, or sexually immature colt contracts the 

 disease, the animal will natural!) eliminate the virus and develop a strong innnunity 

 to reinfection. Infected stallions, on the other hand, are very likely to become virus 

 carriers for a long time. Once stallions are in the carrier state, they transmit the virus 

 to mares during breeding. 



Although the mare will eliminate the virus easily, a pregnant mare infected with EVA 

 may pass the virus to her unborn fetus. As determined by the stage of the pregnancy, 

 the fetus can become infected, die, and be aborted. If the infected foal is born, it will 

 live for only a few days. 



Clinical Signs 



Many horses infected with EVA are asymptomatic. When clinical signs do appear in 

 the acute stage of the disease, they can include any or all of the following: fever, nasal 

 discharge, loss of appetite, respiratory distress, skin rash, muscle soreness, 



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