Recurrence of equine coital exanthema in thoroughbred stallions

Abstract

Abstract : The object of this study was to evaluate recurrence of equine coital exanthema (ECE) whether re-infectionor re-activation of causative virus. ECE is a venereal disease of horses caused by equine herpesvirus type 3 (EHV-3). Like other herpesviruses, it may persist in infected horses for a long time. There is a controversy on the causeof ECE as the recurrence or the reinfection. This disease had occurred firstly on stallions and broodmares in Korea.The horses had rebreeded after healing routinely. Next year, the disease recurrented on the just same affected horsesamong stallions. The result of this study, re-outbreak of ECE in stallions is recurrence of ECE, but not reinfectionof the virus.Keywords : equine coital exanthema, equine herpesvirus type 3, recurrence Equine coital exanthema (ECE) is a venereal disease ofhorses caused by equine herpesvirus type 3 (EHV-3). Lesionsgenerally are confined to the external genitalia of stallionsand mares. The penis and prepuce are the most commonlyaffected areas in stallions. Lesions begin as small, discrete,circumscribed vesicles or pustules that often become conflu-ent [2]. Spread of EHV-3 infection without coitus has beendescribed. Typically, an inapparently infected mare transmitsthe virus to a stallion at the time of breeding. Diagnosis usu-ally can be made on the basis of the characteristic clinicalsigns in mares and stallions. Healing occurs in a few weeks,often leaving depigmented spots. Recurrent coital exan-thema usually occurs in aged broodmares but may also occurin stallions. The relationship between viral recrudescence andrecurrent coital exanthema in the equine is unknown [1].Reoccurrences of ECE are seen, especially after periods ofstress [6]. Some equine herpesviruses are recurrent due toreinfection and reactivation [3]. Like other herpesviruses, itmay persist in infected horses for a long time. Immune carri-ers may have no clinical signs [4]. The disease may reappearthe next season during times of stress or may not be appar-ent for several years, if ever again [5]. However, nothing isknown about the persistence of EHV-3, but it is assumed [7].There is a controversy on the cause of ECE as the recurrenceor the reinfection.ECE had occurred firstly on Thoroughbred stallions andbroodmares in Republic of Korea in 2005. Two stallions ofKorea Racing Authority and many broodmares had expressedtypically clinical signs. In addition, the stallions were con-firmed by the laboratorial examination [8, 9]. The stallionshad rebreeded routinely after healing routinely and had notclinical signs during breeding season. In 2006, ECE hadrecurrent same affected two stallions. The stallions showedclinical signs such as vesicles and pustules on the penis at the