Techniques for localized injections and topical applications of carcinogens at specific endobronchial sites in dogs.

We seek to create a canine lung cancer model with sharply localized carcinomas analogous to human lung cancers. Toward this goal techniques for recurrent endobronchial transbronchoscopic submucosal injections and topical applications of the carcinogens 3,4-benzo(a)pyrene and N-methyl-nitrosourea have been developed. After 2 years of experience with 2,868 endoscopic manipulations and varying dosage schedules in 59 dogs, safe effective techniques for recurrently delivering carcinogens and sequential biopsies of the same sites have evolved. Predominantly during the first year of experience, 10 dogs died as a consequence of technical problems such as exsanguinations after 1 mm. punch biopsies. There were also 39 instances of nonlethal technical complications of endoscopy in the face of immunosuppression and local irritation caused by the carcinogens. By the techniques and dosage schedules described, it has now become possible reliably and safely to create impressive localized bronchial preneoplasia with squamous metaplasia and atypia among the prominent features.