equid gammaherpesvirus 5 equid gammaherpesvirus 5 equid gammaherpesvirus 5 (ehv-5), formerly equine herpesvirus 5, is a species of virus in the genus percavirus, subfamily gammaherpesvirinae, family herpesviridae, and order herpesvirales. it is thought to be the cause of a chronic lung disease of adult horses; equine multinodular pulmonary fibrosis. equid gammaherpesvirus 5 virus classification (unranked): virus realm: duplodnaviria kingdom: heunggongvirae phylum: peploviricota class: herviviricetes order: herpesvirales family: herpesviridae genus: percavirus species: equid gammaherpesvirus 5 synonyms equid herpesvirus 5 equine herpesvirus 5