Lessons learned from rotavirus B – The horse

During the 2021 foaling season in central Kentucky, farms across the region experienced an outbreak of neonatal foal diarrhea. A novel equine rotavirus group B pathogen has been implicated in the disease based on compelling genetic sequencing evidence coupled with the clinical scenario of a highly contagious pathogen that causes diarrhea in foals less than 4 days old. A PCR test for the pathogen was quickly developed at the University of Kentucky, and testing information was shared with labs in the United States, England, Ireland, France, Argentina and Japan. . Unfortunately, the development of an effective vaccine has lagged and disease control has focused on prevention through the implementation of enhanced biosecurity protocols.

Getting a correct diagnosis should never be underestimated, but it can be difficult to understand when there are no cures or protective vaccines available. However, a confirmed diagnosis is essential to guide mitigation strategies, promote vaccine development, and take advantage of increased biosecurity measures and compliance.

The workflow, management culture and practices must be tailored to meet the needs of a particular location. Beyond determining the correct cleaning process, choice of sanitizer, application technique and protective equipment, it’s about understanding how a farm and its team work, not just physically but in team. Biosecurity is as much about leadership as it is about the protocol itself. Time and time again we see the heartbreaking results of a farm crew exhausted from long hours caring for sick animals and adhering to protocol, only to find a crew member who “doesn’t adhere “. A break in this team can be ruinous for epidemic control and disastrous for morale.

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Visits to the farm are a challenge in the face of an epidemic, as we limit the movement of vehicles and pedestrians in vulnerable areas, such as the broodmare. However, it is during these visits that observing how people interact with each other and their charges can be the key to success. Developing a biosecurity protocol is a team effort in which all members contribute to the development of an achievable plan. This can be very difficult to do and suggestions from a third party observer can often be beneficial. Observers can help identify an optimal starting point to help everyone follow the same game plan and communicate the practical aspects of a successful biosecurity plan. Dividing a workforce into units to care for geographically isolated groups of horses can be a useful part of the plan.

Some practical tips to increase biosecurity include wearing gloves, using disposable shoes and footbaths with an appropriate disinfectant, practicing good hygiene between stalls, which includes changing gloves, washing of hands and the absence of organic matter, and the limitation of visitors.

Disinfectants will not work against organic materials (eg feces, dirt, bedding). By simply removing organic matter, the pathogen load can be reduced by up to 90%. Stalls and floors should generally be scrubbed with detergent before applying a disinfectant. Similarly, footbaths with disinfectant will only work if they are clean and changed regularly.

Items used in multiple stalls should be discouraged, but at a minimum they should be sanitized between animals and at the end of the day. All movement in the barn should go from clean to dirty, and foals showing signs of diarrhea should receive additional biosecurity care. Aerosolization of infectious particles can occur with pressure washing or the use of leaf blowers. These practices should therefore be avoided if there are animals in the barn or if the stall is to be occupied shortly after cleaning. Rotaviruses can survive up to nine months in the environment and therefore farms should not spread contaminated litter or manure on their pastures.

The goal of any biosecurity program is to reduce animal exposure to disease, which requires a multi-faceted approach and collaboration between farm staff, visitors and veterinarians. All farms should have basic biosecurity practices in place each foaling season and a plan to rapidly increase biosecurity in the event of an infectious disease event. Until an effective vaccine is available for rotavirus group B, farms will continue to rely heavily on biosecurity practices to slow the spread of this highly contagious disease.

Editor’s Note: This is an excerpt from Equine Disease Quarterly, Vol. 31, number 2, financed by the underwriters of Lloyd’s, London, brokers and their Kentucky agents. It was written by Emma Adam, DVM, PhD, Dipl. ACVIM, ACVIS, from the Gluck Equine Research Center at the University of Kentucky, Lexington.