Alveolar periostitis is a common dental disease of the horse. It is the result of any process which exposes the alveolar periosteum to the action of an irritant. These underlying or causative conditions include such processes as fractures of the teeth, fractures of the mandible or maxilla, wearing the occlusal surface below the gum-line, separation of the tooth and gum by coarse food or dental tartar, deep caries, and canals in the infundibulum due to incomplete filling by cement during the early development of the tooth.