A mat activated indicator is disclosed. The indicator includes a mat to be placed either inside or outside a door. The mat can be activated by an increase in weight such as by a pet stepping on the mat. The mat includes a lower and upper plate which are held apart by a spacer such as a memory foam spacer. An increase in weight upon the mat causes the plates to make contact and close a switch circuit. A transmitter sends a wireless signal upon activation of the switch. The signal is received by a receiving unit. The receiving unit provides an audible, visual, or vibrating signal to provide notice to a pet owner that a pet is stepping on the mat and may want to enter or exit through the door. In various optional variations, the receiving unit produces a signal of musical tones, and may have a choice of musical tones.