[header] How to train an outdoor cat to use a litter box [title] Get an open litter box instead of a closed one. [step] A closed liter box may look nicer and be better at keeping the smells in, but an outdoor cat may not like it. Outdoor cats are used to the open, and a covered box may make them feel closed-in. 
[title] Make sure that the box is big enough. [step] The box needs to be large enough for the cat to be able to move around in.