Investigation of the Shedding of Selected Respiratory Pathogens in Healthy Horses Presented for Routine Dental Care

The main objective of the study was to determine the frequency of detection of selected infectious respiratory viruses and bacteria in healthy horses presented over a 12-month period for routine dental care at 2 veterinary hospitals. Nasal secretions were collected from 579 horses and tested for equine herpesviruses (EHV-1, EHV-2, EHV-4, EHV-5), equine influenza virus (EIV), equine rhinitis A and B viruses (ERAV, ERBV), Streptococcus equi subspecies equi (S equi), S equi subspecies zooepidemicus (S zooepidemicus), and methicillin-resistant Staphylococcus aureus (MRSA) using routine diagnostic quantitative polymerase chain reaction assays. True respiratory pathogens (EHV-1, EHV-4, EIV, ERBV, and MRSA) were detected in 129 (22%) of the horses. Commensal respiratory pathogens (EHV-2, EHV-5, and S zooepidemicus) were detected in 515 (89%) of the study horses. ERAV and S equi were not detected in any of the study horses. The horses showed statistical differences between the 2 veterinary hospitals in regard to breed, age, presence of nasal discharge, rectal temperature, and detection of true and commensal respiratory pathogens. The data generated from the present study supports the risk for the transmission of true and commensal respiratory pathogens from subclinical shedders to susceptible horses. Equine veterinarians performing routine dental care should engage in routine biosecurity practices, with the goal to reduce disease spread.