The use of time-lapse and normal speed photography as a tool in evaluating the effect of cage size on physical activity in the beagle dog was examined. Normal speed motion pictures also served to demonstrate the degree of physical activity possible within specific sized cages, and the effect of changes in external activity on the dogs' activity within the cage. Viewing of these films showed that specific activity measurements can be made, providing a feasible scientific method for evaluating cage activity in a wide range of cage sizes. Physiological data collected over the course of this experiment from dogs housed in 2 different sized cages failed to show a cause-and-effect relationship.