Well, it's been a week of trying different things. After Lance's breathing got so much worse weekend before last, I sent the internal medicine vet the following video and asked for ideas.
Kim called this a "pretty profound obstructive breathing pattern." She figuratively held my hand for the next several days while suggesting treatment and management changes. First, she encouraged the use of a hay steamer; which got Rick to finish it in short order so we could press it into service.
We tried albuterol inhaler treatments every six hours. After the first 24 hours, she directed me to increase the dose. I kept a record of his respirations just before and then 5/10/15 minutes after each treatment. There was a little improvement in respiration rate but not intensity, so we tried two nebulized dexamethasone treatments 12 hours apart. After those, Lance's respirations were maybe a little slower, but with a secondary push that he hasn't had for a number of weeks.
At that point, Kim approved going back to "just" prednisolone and Zyrtec twice daily, and encouraged me to put the horses out 24/7. I had kept them in their stalls/covered paddocks because the "pasture" is so dry and dusty, but Kim said mold is usually the culprit, not dust.
So our new daily routine includes administering meds, putting fly masks on/off, applying insect repellant in the ears, putting horses in/out for evening grain/supplements, steaming hay and transporting to the pasture. I haven't ridden, because Lance's lungs are working so hard just to get air for standing around – and now we're bracing for a record-setting wave.
I am longing for fall, hoping that a change of seasons might reduce Lance's triggers.