In addition, cats may be toilet trained, a sanitary measure which eliminates the litterbox and its attending expense and odor. Training involves about two weeks of incremental moves, such as moving the litterbox until it's near the toilet. For a short time, an adapter, such as a bowl or small box, may be used, suspending the litter above the toilet bowl. When training is complete, the cat uses the toilet simply by jumping up and perching over the bowl. [1]
The first photo is a bit harsh due to the flash photography. Here is a natural light version.