Horse Barn Air Quality
In recent years horsemanship scientists have confirmed that stalls can present significant equine welfare challenges by restricting movement and social interactions. But that’s not all. Study results revealed that they—especially closed box stalls—have much higher concentrations of potentially disease-causing pathogens in the air compared to run-in sheds.

Escherichia coli, staphylococci, mold fungi, and other varieties of disease-causing bacteria hover invisibly in the air of our stables, threatening horses’ and humans’ respiratory health, said Katarzyna Wolny-Koładka, PhD, of the University of Agriculture Department of Microbiology, in Cracow, Poland. And those pathogens circulate in much denser levels when horses are kept closed-up in box stalls.

“Also the dust, formed during maintenance work within the facilities, contributes to the increase in the microbial concentration of the air,” said Wolny-Koładka said.

In their study, the researchers took air samples four times a year (once in each season) for three years from four to five locations within each of three riding stables in Poland:

  • Stable 1, with 15 horses housed in seven indoor box stalls and eight outdoor box stalls.
  • Stable 2—considered “one of the largest and most modern stables in Poland,” Wolny-Koładka said—with 100 horses housed in indoor box stalls.
  • Stable 3, with 30 horses living in groups outdoors with three-sided shelters and a main barn for storage, tack, and rider convenience.

They found very high levels of “bioaerosols”—essentially, organic air pollution—in Stable 2. Average airborne bacteria rates were about 25% higher in Stable 2 than in Stable 1 and about 10 times higher than in Stable 3, she said.

The bacteria identified included Staphylococcus spp., Streptococcus spp., Bacillus spp., and E. coli. Average mold fungi was more than twice as high in Stable 2 than in Stable 1 and more than three times higher than in Stable 3. The fungi species they found included Aspergillus, Fusarium, Mucor, Rhizopus, Penicillium, Trichothecium, Cladosporium, and Alternaria.

Bedding was part of the problem in Stables 1 and 2, Wolny-Koładka said.

“Straw is a source of bacteria and toxicogenic fungi,” she said. “That’s especially true when it is badly stored and damp, because it favors the development of microorganisms.”

Because their study focused on comparing housing types, they did not test different kinds of bedding. However, previous studies have already investigated bedding’s effects on stable air quality.

“The problem in the box stables is also that in the centers that run the box-stall system of horse-keeping, the animals spend a lot of time in their boxes,” Wolny-Koładka said. “Many care and cleaning operations are carried out in a limited, closed space. In addition, there is manure in the boxes and there is feed, straw, and hay for horses in the farmhouses, constituting the source of particulate pollution of air.”

Pathogens can also get into the barns via other sources, she added: “Horses, people, air that flows into the stable, water in containers and pans, soil brought on shoes and hooves to the stable, bird nests, small rodents, cats and dogs often living in stables, insects, damp building materials, such as after flooding, etc.”

Wolny-Koładka recommended owners and managers:

  • Clean stalls and remove used bedding daily;
  • Store straw and hay in well-ventilated, dry areas to prevent mold fungi growth; and
  • Avoid activities such as grooming and clipping in enclosed stalls.

“These behaviors contribute to animal welfare and also translate into sanitary and hygienic conditions prevailing in the stables,” she said.

The study, “Microbiological quality of air in free-range and box-stall stable horse keeping systems,” was published in Environmental Monitoring and Assessment.