Thrush, seedy toe & hoof cracks are three ailments of the hoof that are very common among horses.

Thrush:

Thrush is a degenerative condition of the frog which results in the accumulation of black, foul smelling, moist material in the frog clefts. In the early stages, the horse is sound. If the condition is allowed to progress and extends into sensitive tissues the horse may become lame.