The importance of herpes viruses in equine medicine, with special attention to the population of Iranian horses

The viral diseases can be lead to considerable losses to horse breeding industry. Equine herpesviruses are one of the most important groups of viruses which can cause diseases in horse. In recent years, some of herpesvirus diseases were suspected in Iran. Therefore, the recognition of different aspects of disorders that cause by these viruses can be useful. Five different herpesviruses have been associated with diseases of horses. EHV-1, EHV-3 and EHV-4 are alphaherpesviruses whereas EHV-2 and EHV-5 are gammaherpsviruses. The most epidemiological features of infection with these viruses are similar. For example, they are endemic in horse populations worldwide. Also, there is lifelong latency of infection with periodic reactivation of virus shedding. The disorders cause be equine herpesviruses have various manifestation: Upper respiratory tract disease is caused principally by EHV-4, although disease attributable to EHV-1 occurs. EHV-2 cause respiratory disease, including pneumonia of foals. Equine multinodular pulmonary fibrosis (EMPF) is attributable to EHV-5. Abortion is almost always associated with EHV-1, although rare sporadic cases are associated with EHV-4. Perinatal disease of foals is associated with EHV-1. Myeloencephalopathy is associated with EHV-1 and rarely EHV-4. The cause of coital exanthema is EHV-3. The diagnosis of diseases cause by equine herpesviruses can establish by virological tests, i.e. PCR. Although, there is no specific treatment for this group of diseases, the symptomatic and supportive treatment is advisable