A bacterial (occasionally fungal) infection resulting in the degeneration of the horn of the frog. It is caused by environmental factors such as unhygienic conditions (standing on wet and soiled bedding). The horn is broken down into black necrotic material with a characteristic unpleasant odour. If left untreated, underlying sensitive structures may become infected. Treatment includes removal of all affected horn, application of disinfectants and/or astringents and by moving the horse into clean, dry surroundings.