Field guide to malformations of frogs and toads, with radiographic interpretations

Biological Science Report 2000-0005




In 1995, students found numerous malformed frogs on a field trip to a Minnesota pond. Since that time, reports of malformed frogs have increased dramatically. Malformed frogs have now been reported in 44 states in 38 species of frogs, and 19 species of toads. Estimates as high as 60% of the newly metamorphosed frog populations have had malformations at some ponds (NARCAM, ’99). The wide geographic distribution of malformed frogs and the variety of malformations are a concern to resource managers, research scientists and public health officials. The potential for malformations to serve as a signal of ecosystem disruption, and the affect this potential disruption might have on other organisms that share those ecosystems, has not been resolved. Malformations represent an error that occurred early in development. The event that caused the developmental error is temporally distant from the malformation we see in the fully developed animal. Knowledge of normal developmental principles is necessary to design thoughtful investigations that will define the events involved in abnormal development in wild frog populations.

Additional publication details

Publication type:
Publication Subtype:
Federal Government Series
Field guide to malformations of frogs and toads, with radiographic interpretations
Series title:
Biological Science Report
Series number:
Year Published:
U.S. Fish and Wildlife Service
Publisher location:
Reston, VA
Contributing office(s):
National Wildlife Health Center
16 p.