What have we learned from 7 years of equine rhinitis B virus qPCR testing in nasal secretions from horses with respiratory signs.

BACKGROUND:Equine rhinitis B virus (ERBV) has been given little attention by practitioners compared to other respiratory viruses, mainly because of the lack of diagnostic modalities and association with clinical disease. The objective of the study was to determine the frequency of detection of ERBV in nasal secretions from 6568 horses with acute onset of respiratory signs. METHODS:ERBV-positive qPCR results from nasal secretions submitted to a molecular diagnostic laboratory from 2013 to 2019 were reviewed. RESULTS:A total of 333 ERBV qPCR-positive samples (5.1%) were detected with increasing yearly frequency since the introduction of the assay in 2013. In comparison, only three of 356 (0.8%) healthy horses tested qPCR-positive for ERBV. Median age for ERBV qPCR-positive horses was 3 years of age, and fever, coughing and nasal discharge were the most common signs reported. Further, co-infections with other respiratory pathogens were reported in 73 (21.9%) of ERBV qPCR-positive samples. CONCLUSION:ERBV is a commonly detected respiratory virus from nasal secretions of young horses presenting with fever, nasal discharge and coughing.