Control of Equine Viral Arteritis In The U.S.

Introduction
Equine Viral Arteritis (EVA) is a contagious disease of horses caused by the equine arteritis virus (EAV). The disease does not usually kill healthy adult horses, but it can kill young foals and cause pregnant mares to abort. In stallions, the disease can result in the establishment of a carrier state whereby they can continue to spread the virus.

Equine Arteritis Virus is present in many horse populations throughout the world, but an outbreak in U.S. Thoroughbreds in 1984 was the first time the disease received worldwide recognition. This outbreak prompted many countries to impose import controls on the entry of carrier stallions and EAV-infected semen. These foreign import policies have had significant repercussions on the international trade of horses and semen, particularly in the U.S., where we do not have an import control policy for EVA. The U.S. continues to permit the import of carrier stallions and infective semen and certain breeds have been severely affected by these permissive import policies.

Proper management can easily prevent the dissemination of the equine arteritis virus while allowing the continued use of carrier stallions. This is essential to the horse industry because these stallions often represent the best genetics within their respective breeds. In addition, establishing proper management practices ensures that the health interests, as well as the financial interests, of the horse industry are protected.

Background
Over the past decade, numerous U.S. stallions have been unable to be exported to the European Union (EU) because they are known to shed the virus. Surprisingly, many of these same stallions had been imported from the EU as carrier stallions. The EU was permitting the exportation of EAV carrier stallions and infective semen while preventing the importation of these same stallions and semen because of their EAV status.

The AHC has offered several solutions to address these issues. The AHC has sought the input and support of the states in addressing the unknown EAV status of imported stallions and semen and has asked the U.S. Department of Agriculture (USDA) to establish import regulations requiring that the EVA status of stallions and semen be determined upon their entry into the U.S. so that U.S. breeders could take necessary precautions.

USDA Action and Proposals
USDA has published an Advanced Notice of Proposed Rulemaking (ANPR) that sought public comment on the best way to regulate the importation of horses in connection with EVA and has produced a Uniform Methods and Rules (UM&R) to guide states and the industry in establishing their own programs for addressing EVA through a common set of methods and rules. The document is now available should States decide to implement preventative steps to address EVA.

However, USDA considers the requirements of the World Trade Organization as a barrier to instituting import regulations for EVA because the disease exists in this country and is not under a domestic control program.

Current Status
The American Horse Council met with staff from the National Center for Import and Export within the Veterinary Services of the Animal and Plant Health Inspection Service at USDA to pursue the possibility of establishing an import requirement that determines the serological status of imported stallions and the infectivity status of imported semen. The goal is to provide the U.S. importer with knowledge of any potential risk a stallion or the imported semen may carry if used to breed to a susceptible mare. It is not to prohibit entry of either a stallion or imported semen. The meeting accomplished a number of things, including an understanding that the importation of EAV carrier stallions and infective semen is directly related to the EAV status of the domestic herd. Some issues still need to be resolved, such as liability questions when horses known to be infectious are released from quarantine.

AHC Position
Greater steps must be taken to address the problem of imported stallions and semen whose EAV status is unknown. The AHC will continue to work with the USDA and the states to address the problem of imported EAV-carrier stallions and infective semen and in helping the horse industry learn how to manage these animals in a way that minimizes their risk of exposure.