The Smart Chime wireless doorbell from SmartHome has a push button for people, as you’d expect, and it also has a special paw-shaped doorbell trigger for your pet. You’ll hear a musical chime when the door button is pressed. You can set the pet trigger to “dog” to hear a bark or to “cat” to hear a meow when your pet activates his doorbell button. You train your pet to trigger the paw-shaped button to alert you when he needs to go out or when he wants to come back in. (The paw trigger is safe for outdoor use.) All three pieces are battery operated, and the triggers can be placed up to 100 feet away from the chime unit. The Smart Chime wireless doorbell is $35.99.