equine coital exanthema development in a dutch stallion from a horse riding club in tehran

case history: equine coital exanthema caused by equine herpesvirus 3 (ehv3) was reported in 1900. at the present time, it has become epidemic among horses. the virus could be transmitted via insemination, iatrogenic, and it basically infects the squamous epithelium of the epidermis. clinical presentation: in the first week of january 2012 two mature male horses and a mare were imported from netherland and kept in a stable of a horse riding club located around tehran. in the first week of december, these animals manifested clinical signs of high fever with repeated intermittently for two times. during this period, one of the male horses developed exanthematous lesions on the penis and perinea tissues which depigmented later. biopsy specimens obtained from the lesion processed for histopathological examination were stained with harris h α e and nuclear fast red methods. diagnostic testing: microscopically, ballooning degeneration of squumous epithelium, acantholysis, epithelial ulcers accompanied by multiple bacterial colonies and the herpes virus intranuclear inclusion bodies with margination of nuclear chromatin were evident. obviously the horse had ehv3 infection and the stresses resulted from high fever led to the reappearance of genital exanthematous lesions. assessments: in spite of the contagious nature of the infection, the native horses kept in the same stable did not manifest any clinical sings of the infection and therefore the disease could be native. since the ehv2 infection first affects upper respiratory infection with a high fever course and then induces viremia with another high fever period so it might be speculated that the primary disease of the netherland horses caused by the ehv2 infection.