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New Test for Monitoring Equine Respiratory HealthBy Kentucky Equine Research Staff · January 3, 2017

Recurrent airway obstruction, commonly referred to as RAO or heaves, leaves hundreds of horses unable to participate in athletic events and economically burdens horse owners.

Current management strategies for RAO include:

  • Administering inhaled or systemic corticosteroid anti-inflammatory drugs;
  • Environmental dust reduction strategies, such as low-dust bedding, improved turnout, and appropriate nutrition; and
  • Supplementing with omega-3 fatty acids such as EO•3, a palatable, marine-derived oil rich in omega-3 fatty acids, including DHA and EPA.

How do you know if these treatments are working and if your horse is getting better? What if he is actually getting worse? According to a new study* from researchers in Berlin, Germany, a simple test that measures matrix metalloproteinases (MMPs) could help.

MMPs are a group of enzymes that break down the matrix outside of cells in connective tissues, including the lining of the lung. Excessive breakdown of the matrix by MMPs causes inflammation in the lungs and scar tissue formation. Both of these processes ultimately inhibit the ability of gases—namely oxygen and carbon dioxide—to cross the lung walls. As a result, inhaled oxygen can’t cross the lung tissue to enter the bloodstream, and carbon dioxide can’t leave the bloodstream to be expired. In sum, each gas is stuck in the wrong part of the body because it can’t pass through the damaged lung tissue.

To illustrate this theory, the German research team recruited 10 horses with a history of RAO. They performed a lung wash both before and after treatment with an inhaled corticosteroid, budesonide, combined with environmental dust reduction. The fluid was tested for MMP concentration and activity.

The researchers found that the activity level of all measured MMPs and MMP inhibitors decreased following treatment. They concluded, “Metalloproteinases and their inhibitors…are valuable markers for clinical improvement in RAO.”

In addition, new therapeutic drugs that target MMPs may provide promising new options for the treatment of RAO and the spectrum of equine asthma.

*Barton, A.K, T. Shety, A. Bondzio, et al. 2016. Metalloproteinases and their inhibitors are influenced by inhalative glucocorticoid therapy in combination with environmental dust reduction in equine recurrent airway obstruction. BMC Veterinary Research. 2016 Dec 9;12(1):282.