I think we've cracked it, one of the ponies started with a cough when the weather turned cold, it went on for a few weeks and we started soaking his haynets in a water butt for an hour or two then hanging them out to drain... backbreaking to say the least, then when the freeze came I broke the tap off the bottom of the water butt.... hey ho...
So we tried steaming. Trug full of hay, two kettles of water... still coughing.
Now I think we've got it sussed... this is what we do:
1. Two slices of hay in a trug
2. Tie trug handles with baling string across - stops hay floating up
3. Fill trug with water. Let hay soak for however long, we only soak for 20 mins as we want to wash the dust out not lose nutrients.
4. Tip the trug on its side till most of the water is out then roll it onto your foot and kick it upside down!
5. Leave to drain for half an hour
6. Take it into your feed room, pour 2 kettles of boiling water on the wet hay and cover it with plastic sacks and a thick towel, leave it till it's cooled a bit before you feed it, 20 mins or so.
Voila, Gordon Ramsay would be proud. The coughing chap is coughing no more, he snuffles into his banquet of sweet smelling warm hay with glee. It smells so good I could almost eat it myself.
Edited to add...: It sounds really fiddly and time consuming but once you've got the routine of it, it's as easy as filling haynets and easier than soaking and carting great big sopping haynets. And frozen haynets was the last straw for me.