Equine Rhinitis Virus Study Guide

Overview and Clinical Importance

Equine Rhinitis Viruses (ERV) are highly prevalent respiratory pathogens belonging to the family Picornaviridae. Two distinct species infect horses: Equine Rhinitis A Virus (ERAV) and Equine Rhinitis B Virus (ERBV). These viruses cause acute upper respiratory tract disease that is clinically indistinguishable from equine influenza virus (EIV) and equine herpesvirus (EHV) infections.

Despite seroprevalence rates of 20-90% in horse populations worldwide, ERV infections are often underdiagnosed due to limited availability of diagnostic tests and the predominant focus on EIV and EHV. ERV is now recognized as an emerging cause of respiratory disease outbreaks, particularly in young performance horses. ERV should NOT be confused with rhinopneumonitis (caused by EHV-1 and EHV-4).

Etiology and Classification

Viral Taxonomy

Equine rhinitis viruses are small, non-enveloped, positive-sense single-stranded RNA viruses. They were originally classified as equine rhinoviruses but have since been reclassified based on genomic analysis.