A model of canine tracheal stenosis induced by radiofrequency cauterization.

OBJECTIVE: The current methods of management of tracheal stenosis have disadvantages and are controversial, therefore ideal experimental animal models for the further studies are required. The aim of this study was to establish a new model of canine tracheal stenosis by radiofrequency cauterization.

METHODS: The tracheal cartilage ring was injured by radiofrequency at the level of the sixth tracheal ring in 12 mongrel dogs. A fibrolaryngoscope was used to guide the procedure. The animals were observed after operation and examined after euthanasia. Endoscopic and histological examinations were undertaken to evaluate the progress of stenosis. The degree of stenosis was calculated using the formula: degree of stenosis=(initial lumen area-final lumen area)/initial lumen area × 100%.

RESULTS: Tracheal stenosis had developed in all dogs by the 21st day post operation. Costal retraction was observed in all dogs after the 18th day post operation. At the end of the study, gross and endoscopic examinations showed that stenosis had been induced to a satisfactory degree and without any complications. The median of the degree of stenosis was 92%, with a range of 84-94%. Histological examination showed that cartilage was damaged and that granulation tissue and collagen fibres had formed.

CONCLUSIONS: The model of canine tracheal stenosis induced by radiofrequency cauterization is a relatively simple, reliable, and reproducible animal model. This model may be useful in the development of new methods of treatment for tracheal stenosis.