Balduin Lucké

KIDNEY CARCINOMA IN THE LEOPARD FROG: A VIRUS TUMOR

In the leopard frog (Runu pipiens), the kidney is frequently the site of a malignant tumor, an adenocarcinnma. I n a survey of over 10,000 frogs made ten years ago, the incidence of this tumor was 2.7 per cent.2 While some variation in frequency occurred in different lots, the incidence remained about the same. In more recent surveys, based upon frogs from the northern Kew England States and the adjacent parts of Canada, a similar high incidence has been found. No accurate figures as to incidence in frogs from other regions are available, but tumor-bearing frogs have been obtained in considerable numbers from the Mississippi Valley, North Dakota and Indiana. To date, 1429 frogs with naturally-occurring tumors have been studied in this laboratory. The tumors were more prevalent in males than in females; 1012 (70.8 per cent) of the tumor-bearing frogs were males, 417 (29.2 per cent) were females. An analysis of the series with respect to location and number of tumors is given in TABLE 1, and shows that both kidneys were more frequently involved than either kidney alone. Bilateral tumors were commonly multiple, but solitary tumors predominated when only one kidney was involved.