In their first experiment of the study, Hoover and Drickamer randomly assigned 80 adult female rats to four treatment groups, a control group where subjects were exposed to water, a group where the subjects were exposed to the urine of pregnant mice, a group where the subjects were exposed to the urine of lactating mice and finally a group where subjects were exposed to the urine of a singly caged female mouse. Their findings were that subjects exposed to the urine of pregnant and lactating mice were in oestrus for significantly more days relative to the female mice in the control group or when exposed to the urine of the singly caged female mouse.
