Smoky air makes breathing difficult and can exacerbate equine asthma. | Photo: iStock

A. Having lived in Northern California for many years during large wildfires, I understand your concerns firsthand. A horse’s respiratory system is the main limiter of performance.

While it’s possible to improve cardiac function and muscle mass, as well as the strength and skill to perform certain expectations, the respiratory system cannot be greatly improved through exercise. The ability to transfer oxygen across lung membranes into the bloodstream sets the upper limit on how much oxygen is available to reach muscle tissues. Muscles need oxygen to metabolize fuel stores of fats and carbohydrates using aerobic metabolism.

When a horse is asked to work hard and when adequate oxygen isn’t available, the body recruits anaerobic metabolism, which provides less total energy and can only use carbohydrate as a substrate.  So, a horse with a reduced ability to bring in and transfer oxygen might have to switch to anaerobic metabolism sooner than a horse with a greater ability to deliver oxygen to muscle tissue. Any lung tissue damage will, therefore, have a negative impact on that horse’s performance capacity, so we should consider airway health in horse management, especially performance horse