a supporting base including a generally U-shaped first pad and a first magnetic unit having a plurality of first magnetic tablets, said first pad defining a first discharging opening and being formed with a plurality of spaced apart first retaining holes that are distributed along the length of said first pad in such a manner to surround said first discharging opening, each of said first magnetic tablets being received securely in a respective one of said first retaining holes;

a harness unit connected to said supporting base and adapted to harness said supporting base to an animal; and

a collecting device attached magnetically and detachably to said supporting base and including a generally U-shaped second pad, a second magnetic unit having a plurality of second magnetic tablets, and a flexible collecting bag connected to said second pad and defining an inlet, said second pad being formed with a plurality of spaced apart second retaining holes corresponding respectively to said first retaining holes, each of said second magnetic tablets being received securely in a respective one of said second retaining holes and being attracted magnetically to a respective one of said first magnetic tablets so as to permit attachment of said collecting bag to said supporting base and alignment of said inlet of said collecting bag with said first discharging opening of said first pad,

wherein each of said first and second pads has two free arm portions and a back portion interconnecting said free arm portions, said free arm portions of each of said first and second pads being opposite to each other in a first direction, said free arm portions of each of said first and second pads having bent free ends bent therefrom toward each other, said bent free ends of said free arm portions of said first and second pads cooperatively defining a gap there among, said gap being opposite to said back portions of said first and second pads in a second direction perpendicular to said first direction and being in spatial communication with said first discharging opening in said first pad, and

wherein the first discharging opening in the first pad extends from the back portion to the free ends of the free arm portions of the first pad.