COPD in horses, also called heaves, is characterized in horses by chronic coughing, an increased respiratory rate, low tolerance for exercise, and also forced abdominal breathing which can cause a "heave line" as pictured above.
While searching through the hay horses may inhale dangerous amounts of dust, pollens and mold which can lead to an allergic reaction and COPD. Management of affected horses is heavily reliant on minimizing the exposure to these irritants.
How feeding in a Porta-Grazer can help
When using a Porta-Grazer the rotating pan lifts the hay up to the horse. This allows the horse to tear off a bite without being able to sort thru the hay. Each bite is pulled directly into the mouth. The dust, sand, pollens and mold are shaken loose. Which works its way to the bottom of the barrel. There it is collected in a trough out of the horses reach to be discarded later.
You can also rinse or soak the hay in the Porta-Grazer. All models have a drain plug.