Eight stallions of the French national stud have been castrated and two others removed from the breeding site in an effort to control the spread of a recent outbreak of equine viral arteritis (EVA) in northwestern France.

No new EVA cases have been discovered since Aug. 5. Movement restrictions for the Normandy area were lifted on Sept. 16, according to Hélène de Becdelièvre, spokesperson for the Haras Nationaux.

Among the stallions of the Haras Nationaux, four Norman cobs, three Percherons, and one Arabian have been castrated. Two other stallions–one Barb and one pony–have been transferred to a holding area while awaiting possible full recovery, de Becdelièvre said.

Between June 25 and Aug. 5, equine arteritis virus was detected on 26 farms and breeding centers in the Normandy area, including the national stud center, the Haras du Pin, where the epidemic was first diagnosed after a Percheron stallion began showing clinical signs. Other stallions fell ill within a week. Immediate serological testing was inconclusive, but necropsies following the death of the index case and of a foal in a nearby center confirmed the presence of the EVA virus.

EVA, which can cause fever, edema, and abortion, is mainly transmitted through semen. Affected horses can carry the virus for life after the acute stages of the illness have passed. During the acute stage, the virus can also be transmitted through respiratory route.

Future prevention measures established Monday (Sept. 24) by the EVA discussion committee in Paris will require permanent veterinary monitoring by the RESPE (the Network of Epidemiological Surveillance of Equine Pathologies). For the 2008 breeding season, stallions providing sperm for artificial insemination must be tested for EVA. Vaccination of breeding stallions, while not required, is strongly recommended.

All stallions within the Haras Nationaux, regardless of breeding system or individ