Periodontal disease is one of the most common canine diseases, affecting at least 80% of dogs aged three and over. Periodontal disease begins as gingivitis, where gums become red and inflamed, and may bleed. Untreated, the disease can progress to periodontitis, where the alveolar bone is progressively damaged so that teeth may loosen or fall out. In turn, periodontitis is a risk factor for other diseases like cardiovascular and lung disease.