Coronavirus is becoming a more prevalent problem in horses, affecting from 10-83% of the population with potential fatality rates of 7-27% of adult horses. Researchers investigated equine use of a bovine vaccine against this virus in a dozen healthy adult horses [Prutton, J.S.W.; Barnum, S.; and Pusterla, N. Evaluation of safety, humoral immune response and fecal shedding in horses inoculated with a modified-live (MLV) bovine coronavirus vaccination. Equine Veterinary Education 2019, doi: 10.1111/eve.13175].
The vaccine was given twice at a three-week interval by either oral, intranasal or intrarectal administration. Two horses served as controls. The objective of the study was to identify if there were any abnormal clinical findings or shedding of the modified live virus in feces or nasal secretions.
None of the immunized horses developed any clinical signs—lethargy, anorexia, fever, diarrhea or colic—associated with enteric coronavirus. None of them shed viral vaccine in their feces, although there was a mild and transient fecal character change in eight of the study horses for all routes of administration.
However, two horses shed virus into their nasal secretions for one day following the intranasal route of administration.
Following two vaccine administrations, use of the MLV bovine coronavirus vaccine resulted in a serological immune response in 27% of the study horses.
The investigators summarized: “The modified-live BCoV (bovine corona virus vaccine) is safe to administer to horses via various routes, causes minimal virus shedding and results in detectable antibodies to modified-live bovine coronavirus vaccine in 27% of the vaccinates.”
Due to the limited number of serological responses, the investigators are not recommending this vaccine against equine coronavirus at this time. Future studies are planned to investigate mucosal and cell-mediated immunity from MLV bovine coronavirus vaccine.
