Do any of you have experience with really severe heaves? If so, how did you manage it? 

I had to put my beloved mare down in December due to severe heaves.  I took her to three different vets and they all said that she had the worst case of it they had ever seen.  The heaves damaged her lungs so badly within a period of two months of having her on different steroids and antibodies to try and get it under control that I ended up having to let her go.

Well I hope that you get this figured out for your horse, heaves can be a death sentence if not gotton under control. Does he have the heave lines?

I'm so sorry. . .