Evaluation of thoracic duct healing after experimental laceration and transection

Healing of the thoracic duct (TD) was evaluated clinically and histologically in six healthy dogs. A 2.5 cm longitudinal laceration of the caudal TD was created in three dogs and the caudal TD was completely transected in three other dogs. The site of the defect was identified by placing one 4-0 stainless steel suture in the tissue adjacent to the TD defect. All dogs developed a chylous effusion confirmed by biochemical analysis. By five days after surgery in dogs with TD lacerations, and by 10 days after surgery in dogs with TD transections, thoracic effusion had ceased. Lymphangiography, performed seven days after resolution of thoracic effusion, showed TD patency only in the dogs with TD lacerations. The TD did not appear to be patent in dogs with TD transections. Histologically, in dogs with TD lacerations, one moderately dilated lymphatic vessel was seen at the surgical site in one animal and the thoracic duct and other lymphatics in the two other dogs appeared normal. Minimal perivascular accumulations of neutrophils, macrophages, and lymphocytes were present adjacent to two lymphatics in one animal. A mild increase in fibrous connective tissue and neovascularization was present in the adjacent subpleura. In dogs with complete transections, three to six dilated lymphatics were present at the transection site. Mild thickening of the tunica media was present in one thoracic duct, associated with a "J"-shaped area of condensed collagen, presumed to be a collapsed thoracic duct in one animal. Mild to moderate accumulations of macrophages, lymphocytes, and moderate neovascularization was present in the surrounding tissue, separating it from the underlying connective tissue.(ABSTRACT TRUNCATED AT 250 WORDS)