I have a 26yo retired mare with COPD/Heaves. SHe was particularly bad this last summer. (Before that it was just a bit of coughing).
My vet put her on an aggressive course of Dex (she has no laminitis history)… enough that it made me sit up and pay attention! She also got Ventipulmin (expensive, but… she is worth it). She also gets Smartbreathe from martPak.
WIth the cooler weather she is now on much less dex only 2-3 times a week.
The Dex is not only an anti-inflamatory, but supresses the immune system to prevent a relapse. I wanted to cut it down more, but vet advised against it, as she is tolerating the dex very well.
I wish there was something else, but… I was told about spirulina by someone just today - I might try it. But frankly, I know what real COPD is (I have a good friend who suffers with it) and somehow I doubt some bluegreen algea will cure it.
I soak her hay (fill at AM feeding, feed at night; fill at night feeding feed in the AM…). I use a blue sterlite tub on a dolly that I can tip to spill out the water.