A discovery by University of Guelph researchers should help in understanding how horses develop recurrent airway obstruction (RAO) and offers hope of potential solutions for people with asthma.

In a paper in a recent issue of BMC Genomics, the researchers discuss their discovery that horses have three copies of a gene normally found as a single copy in mammals. This gene, called secretoglobin family 1A member 1 (more simply referred to as SCGB-1A1), produces a protein secreted in large amounts in the airway.

RAO is a chronic inflammatory lung disease. Clinical signs of RAO in horses include coughing, increased respiratory effort (even at rest), nasal discharge but no fever, exercise intolerance, and the presence of a ‘heave line’ (a line running diagonally from the point of the hip forward to the lower edge of the ribs in the external abdominal oblique muscle caused by the persistently increased respiratory effort).

The researchers found that RAO-susceptible horses have much less SCGB1A1 protein in their airways, which enhances inflammation.

The researchers found that two of the gene copies could play a significant role in treating RAO. The third copy has no recognized function and could have evolved into a pseudo-gene.

Lead author Olivier Côté, a PhD candidate in the Department of Pathobiology, says the study could have larger implications than treating horses.

“We’re able to use the horse as a model for asthma in humans,” said Côté. “We found through our research that horses suffering from RAO had reduced SCGB-1A1 levels. Since an obvious suggestion f