An innovative technical approach for repetitive intratracheal instillation without anesthesia in small animals.

Intratracheal instillation in small laboratory animals often involves repeated anesthesia and upper airway intubation. To facilitate this approach, we developed an indwelling system for repeated intratracheal administrations that was assembled from widely available simple components. Its installation can be considered a minor surgical procedure and is done under sterile surgical conditions. This system allows repeated intratracheal administration of substances in the lungs in unanesthetized animals, with the possibility to increase the frequency of instillations and lower the dose. Thoracic radiography was performed to document the reliability of this permanent instillation system. Furthermore, a potent toxic nitrosamine (NNK; N-nitrosamine 4-[nitrosomethylamino]-1-[3-pyridil]-1-butanone) was used to demonstrate appreciable pulmonary toxicity at low dosage but with repetitive administration. This simple technique brings a significant simplification and improvement to small animal studies that require repeated bronchoalveolar administration of substances.