Over the past few years, equine veterinarians have become far more concerned about the spread of infectious disease in equine hospital facilities. This concern is fueled by high-profile cases of drug-resistant bacterial strains and news of the spread of equine herpesvirus.
Fortunately, it is easy to obtain up-to-date disease isolation protocols from reputable sources such as the AAEP and the USDA. However, without good design, good protocol is difficult to maintain. Every veterinarian planning a new hospital should strive to develop solutions that proactively manage biological risk.
Before beginning a design process, it is useful to review the general modes of disease transmission. This allows the design team to develop solutions specific to each risk:
• Direct contact
• Fecal/oral transmission
• Fomite transmission
• Environmental contamination
The first, most important step in preventing direct contact is a master plan of the facility, anticipating direction of future growth and mapping out current and future traffic flow. Many equine hospitals grow organically without the guidance of a master plan. An equine isolation facility that was once on the outskirts of a campus may end up in the middle, which increases the chances of accidental contact between horses.
Placement of the facility is related to your program and your specific protocols, but in either case, the isolation area should be:
• Out of the primary traffic flow
• 75 feet from other buildings
• Designed with a perimeter security barrier
Once inside the isolation facility itself, consider how horses and staff move through the building. Ideally, bring in horses directly through exterior doors. If this is not possible and an interior aisle is required, design the aisle to be 16’ in width.
Many practices are not cautious enough about spreading manure. This is an invitation not only for healthy horses to have contact with contaminated manure, but also for equipment and tractors to relocate and deposit contaminated manure. This issue can be directly related to design; if there is no place to store, stage and pick up contaminated manure, then it may be impossible to follow a careful protocol.
Even a small equine isolation facility needs dedicated space for storage and handling of contaminated bedding. The best storage is in a lidded container such as a dumpster that is downwind of the isolation building. Plan traffic flow to ensure this dumpster is the last pickup for the trash service.
In equine isolation barns, it is of utmost importance to prevent the flow of air from stall to stall as is normal in an unventilated barn. The AAEP’s disease isolation guideline publishes this remarkable statement: “Equine influenza virus spreads effectively as an aerosol over distances up to 50 yards.”
The effort that is placed on preventing the spread of aerosolized disease will depend on many factors, but at minimum, HVAC systems for dedicated isolation barns should be designed to provide the following:
• 100 percent outside air
• Negative pressurization relative to adjacent spaces
• Ducted supply and exhaust to each stall
Even in the smallest equine hospital, at minimum provide one separated stall with an outside access and a large exhaust fan. Stalls that effectively isolate horses should have full-height partitions. This type of fully enclosed environment can be stressful, so provide patients with natural light and as much access to the out of doors as possible given the limitations.
Many of the published disease isolation protocols focus on prevention of fomite transmission. Fomites are contaminated objects, and in an equine hospital they may take the form of contaminated halters, buckets, stall cleaning tools and even clothing.
A good solution for a small equine isolation facility is to provide a separate prep area for each stall where staff can wash their hands, disinfect equipment, store dedicated tools and gown prior to entering the stall. Provide enough area to throw away trash so all tasks can be performed within one space.
In large equine isolation facilities, group horses in wards according to risk and type of disease to prevent already compromised horses from contracting new diseases.
Take the utmost care when choosing materials and finishes in equine isolation stalls. The introduction of moisture to improperly sealed surfaces provides an opportunity for the development of biofilms. Loose rubber mats, notorious for trapping bacteria, should never be used in equine isolation facilities. Flooring should be fully sealed to the substrate below and to all perimeter joints.
Equine isolation facilities often have concrete block walls. Use three coats of a heavy-duty block filler to completely fill pinholes in the block prior to applying a high-build epoxy coating.
Ultraviolet light does wonders for disinfection. If possible, design the equine isolation stalls to open to the outside in a way that allows sunlight to enhance normal disinfection protocols. The horses will appreciate the sunlight as well.
Biological risk management is often presented as the science of infection and disease control. However, there is an art to BRM. The best equine practices are the ones that think big—those that recognize the relationship between design decisions made today and the outcome of those decisions on day-to-day operations over the lifetime of a facility.
Heather E. Lewis, AIA, NCARB, is a principal of Animal Arts, an architectural firm that has exclusively designed veterinary hospitals and animal-care facilities since 1979. The firm has designed projects ranging in size from 2,400 to 85,000 square feet in 40 states, Canada, Australia and Japan and has earned 30 awards for architectural excellence from Veterinary Economics magazine.