Stage 4 advanced periodontitis is defined by:

Stage 4 advanced periodontitis is characterized by more than 50% attachment loss, which indicates a severe progression of periodontal disease. At this stage, significant destruction of the supporting structures of the teeth has occurred, including the periodontal ligament and alveolar bone. This attachment loss can lead to increased tooth mobility and may result in tooth loss if not addressed.

Understanding the severity of attachment loss is crucial in diagnosing and managing periodontal disease. In contrast to the other stages, which describe less severe conditions with lower percentages of attachment loss or focus solely on gingival inflammation, stage 4 highlights the critical nature of advanced periodontitis with considerable structural damage. This stage necessitates intensive treatment, as it reflects a serious impact on the oral health of the animal, warranting both immediate and comprehensive intervention.