Reduced Prevalence of the Lucké Renal Adenocarcinoma in Populations of Rana pipiens in Minnesota2

Northern leopard frogs (Rana pipiens) afflicted with the Lucké renal adenocarcinoma virtually disappeared from Minnesota in the autumn of 1977. Frogs from four sites in Minnesota counties (Polk, Otter Tail, Kandiyohi, and Scott) with a previously high prevalence of Lucké renal tumor were studied. In the past decade, prevalence averaged 4.2% in 29 collections (total, 1,870 frogs). No tumors were detected in 685 frogs autopsied in the autumn of 1977 by the method of previous studies. Frog collections, each comprised of 20 or more individuals, were compared for the presence or absence of tumor-bearing frogs. Significantly fewer collections contained tumor-bearing frogs in the autumn of 1977 than did collections of previous years.