A collecting device includes a discharge collecting member having a bottom board and a bellows member attached on top of the bottom board, and having an expandable chamber formed in the bellows member and enlargeable for receiving and collecting discharge of an animal. An attaching device may attach the discharge collecting member to buttocks portion of the animal, and includes a base member having a retaining member for attaching the discharge collecting member. A chamber pot may be attached to the attaching member for collecting piss. A wearing device may be attached to the animal for coupling to the attaching device.