Breeding trouble

Equine viral arteritis may be rare in the UK, but we cannot afford to be complacent, warns Karen Coumbe MRCVS

WITH vague signs and the ability to spread undetected via silent “shedder” stallions, the infectious disease equine viral arteritis (EVA) has the potential to cause havoc within the UK breeding industry.

EVA is caused by the equine arteritis virus and is found virtually worldwide, including in mainland Europe where there is high horse population immunity and low-grade signs of the disease.

Evidence suggests the global incidence of EVA is increasing. While the UK has remained relatively unaffected, this means our equine population has little or no immunity and would be highly vulnerable to infection when or if the virus recurs here again.

EVA is unusual in that it is spread by both respiratory and venereal routes. The disease is rarely life-threatening to healthy adult horses, but can result in abortion in mares and, infrequently, death in young foals.

The most serious issue is that some stallions are apparently healthy carriers of infection, shedding the virus in their semen. Mares mated with or inseminated by such shedder stallions may become infected and spread the disease to others by the respiratory route.

The disease can be transmitted by all forms of artificial insemination (AI); neither chilling nor freezing will destroy the virus, which is preserved in the semen. Antibiotics commonly used in semen extenders have no effect on its survival. The consequences of an outbreak could be devastating, both for individual studs and the wider equine industry.

HIGH-RISK SITUATIONS

MECHANISMS are in place to prevent the introduction of EVA to the UK via semen imports.