Pulmonary lymph node charting in normal dogs with blue dye and scintigraphic lymphatic mapping

The prognosis of dogs with primary lung tumors and lymph node metastasis is poorer than of dogs without metastasis. Biopsy of intrathoracic lymph nodes is recommended, but without specific guidelines. This study investigated incorporation of a human lymph node classification in normal dogs with intercostal thoracotomies. Methylene blue and technetium-99m sulfur colloid lobar injections were used for enhanced nodal identification. Descriptive comparisons were made for lymph node resections utilizing both veterinary and human anatomic lymph node charts. A median of 2 (range 1–4) lymph nodes were removed per hemithorax in vivo versus a median 6.5 (range 2–8) lymph nodes removed ex vivo from each hemithorax following in vivo dissections. Incorporation of a human thoracic lymph node classification system may be useful for future clinical application in dogs. Future use of either methylene blue or technetium for canine thoracic lymphadenectomy needs to be evaluated further.