"The purity of a person's heart can be quickly measured by how he regards cats." --Unknown ^ quote
To train your rabbit to use a litter-box in a selected area, choose a litter-box that is the right size for the bunny. Don't force a tiny dwarf rabbit to leap into an enormous, high-sided box designed for a gigantic cat--and don't make your French Lop squeeze his big frame into a toaster-sized toilet. The litter-box should be comfortable, and located in a quiet, private place.
Pygmy Goats - I've had two or three and, believe me, they're very clever and as agile as deer! I spent a lot of time repairing fences! Yes, they're cute and a barrel of fun........but need regular hoof trimming as well as annual worming and shots. And, of course, daily alfalfa or lower-protein hay and a little sweet feed (mostly oats, I think).