Oral disease is one of the most common diseases found in dogs. It is caused by the buildup of various anaerobic bacteria in the mouth which forms plaque, eventually hardening into tartar on the teeth along the gum line, and is related to the development of gingivitis. Since small and toy breeds have a much smaller jaw but contain the same number of teeth, crowding allows higher bacterial build up and puts them at higher risk of developing periodontal disease.