young foal

During the 2021 foaling season in Central Kentucky, area farms experienced an outbreak of neonatal foal diarrhea. A novel equine rotavirus group B pathogen was 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 under 4 days of age. A PCR test for the pathogen was quickly developed at the University of Kentucky, and testing information was shared with labs in the U.S., England, Ireland, France, Argentina, and Japan. Unfortunately, the development of an efficacious vaccine has lagged behind, and disease control has focused on prevention through the implementation of increased biosecurity protocols.

Obtainment of a correct diagnosis must never be underestimated, but this can be hard to comprehend when there are no available cures or protective vaccines. However, a confirmed diagnosis is vital in order to guide mitigation strategies, promote for vaccine development, and leverage for increased biosecurity measures and compliance.

Workflow, management culture, and practices should be adapted to meet the needs of a particular location. Over and above determining the correct cleaning process, disinfectant choice, application technique, and protective equipment is the process of understanding how a farm and its crew work, not only physically but as a team. Biosecurity is as much about leadership as it is about the actual protocol itself. Time and again we see the heartbreaking results of a farm crew worn down by long hours tending sick animals and adhering to a protocol, only to find one member of the team who does not “buy in.” One breakdown in that team can be ruinous to the control of an outbreak and disastrous for morale.

Farm visits are a challenge in the face of an outbreak as we limit vehicular and foot traffic in vulnerable areas, such as the foaling barn. However, it is on these visits where observing how people interact with each other and their charges can be the key to success. Development of a biosecurity protocol is a team effort where all members contribute thoughts on how to make a workable plan. This can be very hard to do, and suggestions from a third-party observer can often be beneficial. Observers can help identify an optimal starting point to help get everyone on the same game plan and communicate the practicalities of a successful biosecurity plan. Division of a workforce into units to care for groups of geographically isolated horses can be a helpful component of the plan.

Some practical tips for increasing biosecurity include wearing gloves, using disposable footwear and foot baths with appropriate disinfectant, practicing good hygiene between stalls, which includes changing gloves, washing hands and being free of organic material, and limiting visitors.

Disinfectants will not work in the face of organic material (e.g., feces, dirt, bedding). By simply removing organic material, the pathogen load can be decreased by up to 90%. Stalls and floors typically require scrubbing with a detergent prior to application of a disinfectant. Similarly, foot baths with disinfectant will only work when they are clean and changed regularly.

Items used in multiple stalls should be discouraged, but at a minimum they should be disinfected between animals and at the end of the day. All movements in the barn should proceed from clean to dirty, and foals showing signs of diarrhea should receive extra care in biosecurity. Aerosolization of infectious particles may occur with pressure washing or with the use of leaf blowers, so these practices should be avoided if there are animals in the barn or if the stall is expected to be occupied shortly after cleaning. Rotaviruses may survive up to nine months in the environment and, therefore, farms should not spread contaminated bedding or manure onto their pastures.

The goal of any biosecurity program is to reduce the exposure of animals to disease, requiring a multifaceted approach and collaboration between farm personnel, visitors, and veterinarians. All farms should have basic biosecurity practices in place each foal season and a plan to rapidly increase biosecurity in the event of an infectious disease event. Until an efficacious 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, Issue 2, funded by underwriters at Lloyd’s, London, brokers, and their Kentucky agents. It was written by Emma Adam, DVM, PhD, Dipl. ACVIM, ACVIS, of the University of Kentucky’s Gluck Equine Research Center, in Lexington.