Read Pete Ramey’s articles at hoofrehab.com, specifically the one on thrush remedies. (In fact, read everything on his site! He cross-references Dr Kellon’s work heavily!) Anyway, his mixture of 8 ounces of 40% zinc oxide ointment: 2 teaspoons of copper sulfate powder was the ONLY application that brought healing to Tuck’s chronic deep central sulci thrush challenge. I purchased the cheapest diaper rash ointment (4oz for $2) & copper sulfate pentahydrate powder 1lb (also cheap) & voila! A Godsend!