To develop a smaller size gerbil one would use runts, or adults that are small. However, there are many risks involved, due to birth complications or other unknown reasons. Perhaps, spotted small gerbils would work because their litters are smaller anyway due to the spotted gene. I suppose its possible. Smaller breeds have been developed in other animals - Chihuahua, Netherland dwarf, Bantams, Singapura, Argentina miniature horse, Vietnamese potbelly pig, etc... -- Gary's web pages - http://home.talkcity.com/StudioDr/go5
