ABSTRACT. Lymph drainage routes from the abdominal and pelvic cavities in beagle dogs were observed serially by following the time course of India ink administered intraperitoneally. Four systems of lymph drainage routes from the peritoneal cavity were observed in this study. The earliest drainage returned to the cranial mediastinal lymph nodes via the sternal lymph vessels; subsequently, the sternal lymph nodes located along the internal thoracic artery became involved. Then, a drainage route via the lymph vessel along the left vagus nerve was observed. The final drainage route flowed into the lateral lymph vessel through the thoracic duct located on the vertebra. These results show that India ink is absorbed from the peritoneal cavity, and that the lymph drainage first flows mainly towards the cranial mediastinal lymph nodes through the ventral lymphatic channels. Our serial observations suggest that, over time, the lymph drainage routes changed from the ventral abdominal to the dorsal thoracic lymphatic channels in the thorax. KEY WORDS: beagle dog, lymph drainage, peritoneal cavity.J. Vet. Med. Sci. 68(11): 1143-1147, 2006 The lymphatic system establishes a lymphatic circulation and transports lymph containing lipid droplets, immunocytes, and tumor cells. Ultimately, lymphatic drainage routes flow into the systemic circulation. However, parts of the lymphatic system are located in serous cavities. These lymphatic routes have yet to be adequately clarified. Previously, a limited amount of information about the lymphatic drainage from the abdominal cavity was collected by examining the route that drains lymph from the canine peritoneal cavity [6]. Tracing marker administered into the peritoneal cavity was found to travel via the diaphragm to the sternal lymphatics located in the ventral inner-wall of the thoracic cavity. Subsequently, the same drainage pattern was observed in many animals [4,7,9]. This lymphatic drainage route may be clinically useful in predicting the course of intraperitoneal cancer dissemination. The present paper provides a detailed description of lymph drainage routes over time following the intraperitoneal administration of India ink in beagle dogs.
MATERIALS AND METHODSThree adult male beagle dogs (body weight, 8.5 kg) and one adult female beagle dog (body weight, 6.7 kg) were used for this experiment.Using a fine needle, the male dogs were all injected intraperitoneally with warm India ink dissolved in physiological saline at a dose of 25 ml per kg body weight; the India ink was injected into the pelvic cavity via the rectum in the female dog. The male dogs were sacrificed by an overdose of Nembutal (0.2 ml/kg) at 30 min, 60 min, and 2.5 hr after ink injection, respectively. The female dog was sacrificed at 2.5 hr. A fixative solution [24 (ethylene glycol): 8 (phenol): 1 (formaldehyde solution): 16 (methanol)] was immediately injected intraperitoneally and intrapelvically after the animals were sacrificed. The peritoneal and pelvic cavities were dissected from the carcasses, and these ...