I stabled my horse and pony at a fancy Grand Prix level hunter/jumper barn and they told me this tip for our pony's thrush, which always happened no matter how clean the stall was (we live in a rainy area). Use a medicine sold in a syringe called "Today" by Fort Dodge and shoot it into the affected area including well into the frog. It clears up the thrush in days if not faster. Tough cases may need a second dose. It is sold for cows (Lactating) and the ingredients are Cephapirin sodium. The ingredient in "Tomorrow" (for dry cows) is cephapirin benzathine. Either one works well. Hope it helps. Our local tack shop now stocks it and one dose only costs $3.