That's the hardest part, not having a name.
I talked to the vet and one thinks it has to be a heart problem, but I am rather confused. Spice is running, bucking and tearing around her field, and they are telling me if I ride her any amount she's going to kneel over from heart failure. Her pulse is strong, I even asked another more experienced horse person to check it for me. Even with a stethoscope it sounds normal, even after light exercise, aka me and her walking and trotting about in hand.
Yes there is still a little edema in her pasterns and chest but could it not be going away due to lack of movement lately? It's been pouring rain on and off the past week and she only gets some exercise and turnout when it drys up a little, so she doesn't slip in the slick as snot mud.
The vet is coming out next week and we're talking more than, about other possibilities and treatment.
Very much possible the lack of movement causes the swelling to not go away. Can you at least hand walk her daily, maybe even twice daily no matter what weather it is? That would get her circulation going and help getting rid of the waste products (swelling).
Don't know much about heart disease in horses, but I had a senior who died from heart failure most likely due to COPD and a mare with the same, COPD and heart failure. The gelding was 26 when he died suddenly, in pasture, chasing a mare in heat, no signs of any distress btw.
The mare was sick, really sick and I had the appointment to put her down, but she decided for herself.
Your horse doesn't sound sick at all(bucking, kickin, running and regular heart beat), which makes me think again it was an allergic reaction.