What is a sign of poor dental health observed in the examination of lymph nodes?

Enlarged lymph nodes are a significant sign of poor dental health, particularly because dental disease can lead to systemic infections and inflammation that affect the surrounding lymphatic structures. When a dog has dental problems such as periodontal disease or tooth abscesses, bacteria can enter the bloodstream and cause regional lymph nodes, such as the mandibular or submandibular nodes, to respond by enlarging. This enlargement indicates an immune response to infection or inflammation in the oral cavity, highlighting a direct link between dental health and the condition of the lymph nodes.

The other options, while they may indicate various health issues, do not specifically correlate with dental health in the same way. A shiny texture may suggest normal health or fluid presence but lacks direct relevance to dental issues. A rough texture might be more indicative of chronic inflammation or other systemic diseases rather than a primary dental problem. Discolored nodes could arise from various conditions but do not specifically signify poor dental health in the same manner as the enlargement, which directly points to the body's response to oral infections or disease.