PRIMARY LUNG NEOPLASIA IN A BEAGLE COLONY

As part of long-term pulmonary carcinogenesis studies in dogs, it is i mportant to analyze the incidence of spontaneous lung neoplasia. Prima ry lung carcinoma incidence was determined in two control populations of Beagle dogs observed for their life spans. One population comprised 216 dogs (112 males and 104 females) that were controls for life span studies, and another comprised 182 dogs (50 males and 132 females) th at were retirees from a breeding colony. Forty lung neoplasms were not ed in the 398 dogs; 35 neoplasms were carcinomas classified as papilla ry adenocarcinoma (20), bronchioloalveolar carcinoma (9), adenosquamou s carcinoma (5), or bronchial gland carcinoma (1). The other five neop lasms were a malignant fibrous histiocytoma, three adenomas, and a fib roma. The crude incidence of lung carcinomas averaged for both populat ions was 8.8% (35/398) and was dominated by a relatively high incidenc e of lung neoplasia in aged dogs, those dying after the median life sp an of 13.6 years.