Gallstones have occurred in laboratory animals only after certain artificial conditions are met. Shortly after 1950, it was found that a colony of deer mouse (Peromyscus maniculatus) occasionally bore gallstones spontaneously.1 This provided a unique opportunity to investigate gallstones occurring naturally in a suitable laboratory animal. A colony of 6,416 of these animals was maintained over an eight-year period, and examination of the records of this colony has revealed groups in which there is a higher incidence of gallstones than in others. Maintenance of this colony provides the opportunity to study chemical and hormonal as well as genetic factors influencing formation of stones in this species.
The American deer mouse is one of the most widely distributed animals on the North American continent. It ranges from the Atlantic to the Pacific oceans and from the Arctic Circle to the Isthmus of Tehuantepec. Peromyscus maniculatus has been modified into more