One of my girls thought it was fun to shred the pee pads (she also thought it was fun to swim in her water bowl in the middle of the night...not me!) so I bought a tray from Petco and that solved the problem. I tried the washable pads and they started thinking my smaller rugs were pads too (since they were soft fabric under their feet) so I did away with them...now that they are all grown up I just lay a disposable pad at the back door during the night and if we leave for the day and they don't distroy it anymore.
I didn't throw the washable pads out though, I use them on the seat of the car when we take the girls with us...they protect the seats from accidents, car sick babies and wet or dirty feet
