Years ago, I purchased one of those kits to train the cat to use the toilet. You place the litter box across the seat and train the cat to use that box. After a few weeks, you remove the litter box and the cat is supposed to “know” to straddle the seat and poo in the potty.
Well all went well until I removed the litter box. The first time the cat tried to jump up to the seat, he fell in. He never used the toilet again, even after I put the litter box back on.
Cheers,
Vega