EVA Advice for Members

The International Collating Centre at the Animal Health Trust has advised the Thoroughbred Breeders’ Association as follows:

Equine Viral Arteritis (EVA)
On 27^th April 2012 the Réseau d’Epidémio-Surveillance en Pathologie Equine (RESPE) reported that in recent weeks, the Frank Duncombe Laboratory (Normandy, France) had identified seroconversions to equine viral arteritis (EVA) in five mares. Serology showed increased antibody levels between samples taken in the two breeding seasons of 2011 and 2012 in these mares, which were negative in 2011 and positive in 2012. It appears that the virus circulated in the period sometime between the two blood tests.
The five cases include i) three Thoroughbred mares in Calvados, which were 6-, 17- and 20-years-old, respectively, ii) a single 9-year-old French-saddle mare in Ille-et-Vilaine that also aborted last December, iii) a single 7-year-old Anglo-Arab mare in Mayenne. Other than the abortion in the French-saddle mare in December 2011, which was not investigated for EVA, no other clinical signs were observed in these animals. An epidemiological investigation is underway in each case.

TBA advice to Members
The TBA advise that members with mares returning from France this season isolate them while a blood sample is tested for EVA antibodies. Any mares that are shown to have positive antibody titres should be maintained in isolation until another blood sample, collected at least 14 days after the first one, is tested
by the same laboratory in the same assay and results show that titres are either stable or declining. Unlike stallions, mares do not become carriers of EVA. After they have recovered from the acute phase of the infection, when they show no clinical symptoms of disease (conjunctivitis and nasal discharge) and their blood antibody titres are no longer rising and are either stable or declining, mares are considered no longer infectious to other horses and immune to EVA for life.