Stabled horses are exposed to numerous respiratory and GI pathogens, including viruses, bacteria, mold spores, dust mites, and parasites. Stable environments affect disease transmission based on air quality and ventilation, population density, and general cleanliness. Barns should be constructed to optimize ventilation and light, minimize exposure to dust and molds, provide temperature regulation, facilitate cleaning and disinfection, ensure proper bedding and provide ample space for each horse. Windows and skylights provide sunlight and natural ventilation. Sunlight is a potent killer of many bacteria and viruses; it also promotes coat shedding and regular estrous cycles.
Eight air changes per hour is considered adequate ventilation for temperate climates and average humidity. Ceiling or wall-mounted fans can be used to increase air circulation on hot, humid days. Stall doors open at the top or made of heavy mesh screening provide better ventilation. Stalls should have nonslip flooring and walls or partitions that prevent direct contact between horses in adjacent stalls. Suggested stall dimensions for adult horses and for mares with foals are 3.6 × 3.6 m and 5 × 5 m, respectively. Doorways should be at least 2.4 m high × 1.2 m wide.
Equine asthma syndrome (chronic obstructive pulmonary disease) and noninfectious inflammatory airway disease are associated with airway hypersensitivity to environmental allergens and irritants and exposure to organic dust. The most commonly incriminated allergens are fungal spores and pollens; however, barn dust is also rich in particulates from shavings, sawdust, manure, hay, animal hair and dander, silica from dirt in indoor arenas, and endotoxin. The amount of air contaminants increases with the dustiness of the barn, bedding, and forage. Management techniques that help prevent this condition include:
substituting wood chips, peat moss, or shredded paper for dusty straw bedding
avoiding dusty concentrates
using shallow rather than deep feed containers
soaking hay before feeding at ground level
not storing bedding and feed above stalls
situating riding areas and the dust they generate away from stalls
Feeds should be stored in dry containers to decrease contamination with molds and animal excreta. Feeding moldy hay and silage has been associated with cases of equine botulism. Opossum feces can transmit infective sporocysts of Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis. Contamination of feeds by rodent or deer urine has been incriminated in the spread of certain strains of Leptospira.
Regular disinfection of stables and feed and water buckets helps decrease persistence of infectious agents in the environment. Organic debris inactivates most chemical disinfectants; therefore, disinfection should begin with physical cleaning (ie, hosing, scrubbing) of all surfaces, followed by chemical disinfection. Phenols, quaternary ammonium compounds, and chlorine are the most commonly used disinfectants.
To further decrease the spread of infectious disease, stalls should have walls or partitions to prevent direct contact between horses in adjacent stalls. Pregnant mares, mares with foals, and weanlings should be kept separate from yearlings and adult horses. Ideally, new arrivals should be isolated from the resident horse population for 30 days to decrease introduction of infectious respiratory diseases, such as equine influenza virus, equine herpesviruses 1 and 4, and Streptococcus equi.
Alcohol-based hand sanitizer gels are very effective against most infectious respiratory viruses and bacteria. Wall-mounted hand sanitizer dispensers can be placed strategically throughout barns and tack rooms to improve hand hygiene and to decrease transfer of infectious diseases.
