Those who claim that horses frogs can actually have a yeast infestation, say the the difference between the fungus and the thrush is as this:

Difference between fungus and thrush: If you swipe a hoofpick deep into fungus-infected tissue, it will smell "cheesy" like a yeast (Candida) infection. The back half of the frog peels off in deep layers, and the frog never becomes a wide, healthy triangle. The diseased tissue is light gray to white in color, or black between the peeling layers; healthy frog is medium gray.

By comparison, thrush has a nasty, rotten smell, the tissue is black and slimy, and it tends to begin in the collateral grooves. Thrush is another wet-season problem. In wet areas, people use Kopertox daily in the grooves of their horses' feet but it is a nasty poison, both for us and the horses, and in the environment. "Thrush-buster," which contains Gentian Violet, is also effective and is not poisonous.

Not so proud member of the WACHNRMG club