En uppföljning av analysresultat (serologi och virus) av EAV på seminhingstar i Sverige år 2002 och 2005.

Abstract: EVA, Equine Viral Arteritis, was diagnosed for the first time in 1953 in USA. The disease gained international interest in 1984, when there were several outbreaks of abortion at Thoroughbred studs in USA. EAV, Equine Arteritis Virus, is an RNA virus in the Arteriviridae family. There is only one serotype of EAV but several strains and the strains have different virulence. EAV is transmitted in two different ways: by aerosols, or by venereal transmission. Stallions often become chronic shedders. For diagnose of EAV, serology or a method to detect virus, for example PCR, can be used. Since 1996 EVA is included in the Swedish act about artificial insemination in horses. All stallions used with AI should be tested serologically for EAV, if tested positive the semen has to be analysed for virus. In Sweden stallions with viruspositive semen are allowed to be used for breeding. The aim of this study was to investigate if the Swedish rule about EAV in stallions used for AI was followed and to investigate the prevalence of EAV in stallions used for AI. The breeds included in the study were Swedish Warm Blood, Standardbred trotter, North Swedish trotter and English Thoroughbred. Data about the number of stallions with breeding permission was collected from the breeding associations. Data about the results of EAV analyses (serology and PCR) were collected from SVA: s data reading system. The results varied among the different breeds. In the Standard bred stallions the rate of sampling varied between the years, from 81 % (2005) up to 92 % (2002). The prevalence of serological positive Standard bred stallions decreased from 43 % in 1999 to 41 % in 2002 and to 28 % in 2005. In the North Swedish Trotter and the Swedish Warm Blood the rates of sampling were higher and the prevalence's were lower. In the English Thoroughbreds the sampling started in 2005, a demand from their breeding association. The stallions that were serological positive were all vaccinated abroad. Year 2005 there were only two stallions (Standardbred trotters) with virus in their semen. No EAV in aborted foetuses has yet being diagnosed. Conclusion: Despite the fact that stallions positive for EAV in semen were allowed for breeding, the prevalence of positive stallions has not increased.