Primary pulmonic tumors in beagles.

The age-specific frequency of 11 primary pulmonic neoplasms in a closed Beagle colony is presented. The first tumor occurred at 5 years, and the frequency increased progressively in the older age classes. All of the tumors arose from sites distal to the principal bronchi. Although metastases appeared to occur relatively late, with respect to course of tumor development, they were noted in approximately a half of the dogs and most frequently involved the bronchial lymph nodes.