Years ago I had a project TB who was footsore with horrible thrush that was making him more lame. I tried everything to get the thrush under control.
At the time and with my knowledge then, I thought most of the lameness stemmed from needing specialized shoeing and the thrush was just an annoying, secondary issue. Turns out I had it backwards.
In desperation to get him sound, I took him to the chief farrier at UPenn at the time- Rob Sigafoos, co-founder of Sound Horse Technologies, inventor of the Siagfoos shoe, etc. I was prepared to do whatever it took to get him sound.
Rob gave me two of the best pieces of advice I have ever received: 1. Pull his shoes. 2. Treat all thrush like a skin wound.
For the thrush, he got me some Panalog to get the inflammation under control and told me just to clean it regularly with something that won’t irritate the tissue. Don’t put anything on it you wouldn’t want to use on a wound on your own skin. (Like most of those OTC thrush treatments- he said stay away from those for my horse because they can damage the tissue and prevent healing)
Dry is great, too, if you can manage it, but horses also need to move, so staying in a stall or small drylot isn’t necessarily helpful.
For the past 15+ years, I have had almost no problems with thrush. When I have had a great trimmer, I literally have had no problems with thrush. When I have had “meh” farriers, I’ve had no problems I couldn’t get under control easily cleaning the area with 4x4s and a mild chlorohexidine, betadine, soap, etc. My horses live out in unavoidable slop all winter, so it’s not like it’s great husbandry on my end preventing issues.