Equine herpesviruses. 6. Sequential infection of horses with types 2, 3 and 1.

The immunological and virological status of 3 foals in respect of equine herpesviruses (EHV) was established and the foals were sequentially infected with EHV2, EHV3 and EHV1. Following experimental infection with EHV2, no clinical signs of disease were observed in any foal. The inoculation of EHV3 into the genital tract resulted in lesions of the mucous membrane and perineal skin that were considered typical of equine coital exanthema. Following intransal inoculation of EHV3 extensive ulceration and pustule formation on the nasal mucosa was observed by day 5 accompanied at day 7 by a profuse, mucopurulent nasal discharge; on day 8 pustular lesions of the skin about the external nares appeared. Signs of disease after inoculation with EHV1 were milder than expected in 2 of the 3 foals. The possibility that recent, prior infection with EHV2 and/or 3 may protect against EHV1 was considered.