Thrush is an anaerobic bacterial infection that infects the tissue of hooves. It is characterized by black, tarry, foul-smelling material in the frog of the hoof. A horse with thrush should be kept in a dry environment (regular stall cleaning and turnout in a dry area) and hooves should be cleaned out daily. Dilute bleach (1 part bleach to 10 parts water) or a commercial product, such as Kopertox, should be applied daily and then decreased to once or twice weekly until the thrush has resolved. If thrush is not treated it can infect the deeper tissues of the hooves and can lameness. Contact your veterinarian if your horse’s thrush is associated with lameness, if the thrush is refractory to treatment, or if your horse has recurrent bouts of thrush.