Ultrasonographic evaluation of the reproductive tract is an important component in the evaluation of the bitch and queen. Information is obtained concerning normal events involving the reproductive system (eg, ovulation, pregnancy) as well as pathologic conditions (eg, ovarian cysts, metritis). The appearance of the female reproductive tract normally changes with phases of the cycle; these changes need to be interpreted with knowledge of the ovarian cycle. Serial ultrasonographic evaluation of the diseased reproductive tract can be very helpful in evaluating response to therapy.