By nature, rabbits choose one or a few places (usually corners) to deposit their urine and most of their pills. Urine-training involves little more than putting a litterbox where the rabbit chooses to go. Pill training requires only that you give them a place they know will not be invaded by others. Here are some suggestions to help you to train your rabbit to use the litterbox.
Older rabbits are easier to train than younger rabbits, especially babies. A rabbit's attention span and knack for learning increases as they grow up. If you have a baby, stick with it! And if you are deciding whether to adopt an older rabbit, or litter train your older rabbit, go for it!
This is often the most important factor. When rabbits reach the age of 4-6 months, their hormones become active and they usually begin marking their territory. By spaying or neutering your rabbit, he will be more likely to use his litterbox (as well as be much healthier and happier).
Use a litter made from plants or paper. Some brands to look for: Cat Country, Critter Country, and Yesterday's News. (Carefresh used to be ok but they recently added baking soda for a period, so it may not be safe. It's best to avoid this product for now.) You can also use horse bedding (available at feed stores) or wood stove pellets. These have been heat-treated in the manufacturing process, so they don't present the same hazards as soft wood shavings, which can cause liver damage in rabbits. Silica, clay, and clumping cat litters are dangerous for your rabbit, and should never be used. Corn & wheat based litter also should be avoided, because rabbits will often ingest it.. Another approach is to place a handful of hay in each box, or to simply use hay as litter. It is helpful to put several layers of newspaper under the hay, to absorb urine. Most newspapers today are using soy-based ink, which is safe for your rabbit, Obviously, you need to change the hay fairly frequently (daily), since your rabbit will be eating it. This method often helps to encourage good litter habits as well as to encourage hay consumption, since rabbits often eat at or near the same time as they use the litter box.
Clean litterboxes often, to encourage your rabbit to use them. Use white vinegar to rinse boxes out--for tough stains, let pans soak. Accidents outside of the cage can be cleaned up with white vinegar or club soda. If the urine has already dried, you can try products like "Nature's Miracle" to remove the stain and odor. To dispose of organic litters, they can be used as mulch, or can be composted. Rabbit pills can be directly applied to plants as fertilizer.
Place the box in the corner of the cage that he goes in. With a litterbox in the cage, when the rabbit is confined to his cage when you're not home, cage time is learning time. Hang the hay rack over the litterbox since rabbits often eliminate at or near the same time they are grazing on their hay. Don't use litter as bedding for the cage, as your rabbit will think the entire cage is his litterbox!
All rabbits will drop pills around their cages to mark it as their own. This is not failure to be litter-trained. It is very important for your rabbit to identify the cage as her property so that when she leaves the cage for the bigger world of your house, she will distinguish the family's area from her own and avoid marking it. To encourage this, make the rabbit the king of his cage. Try not to force him in or out of it-- coax him. Do not do things to his cage that he doesn't like, or things to him that he doesn't like while he's in the cage.
Even if your goal is to let your rabbit have full run of the house, you must start small. Start with a cage and a small running space, and when your rabbit is sufficiently well-trained in that space, gradually give her more space. But do so gradually! If you overwhelm her with too much freedom before she's ready, she will forget where her box is and will lose her good habits.
Start with a box in the cage, and one or more boxes in the rabbit's running space. If she urinates in a corner of the cage not containing the box, move the box to that corner until she gets it right. Don't be concerned if your bunny curls up in his litterbox -- this is natural. Once she's using the box in the cage, open her door and allow her into her running space. Watch her go in and out on her own. If she heads to a corner where there's no box, or lifts up her tail in the characteristic fashion, cry "no" in a single, sharp burst of sound. Gently herd her back to her cage and her litterbox, or into one of the boxes in her room. Be careful, however. You don't want to make the cage or the litterbox seem like punishment. A handful of hay in the box makes it a more welcoming place. After she first uses the box, praise her and give her her favorite treat. Once she uses the box in her room a couple of times, you're well on your way, as her habits will be on their way to forming. As she gets better trained in her first room, you can increase her space. Don't hurry this process. And if the area becomes very big, or includes a second floor, be sure to include more litterboxes, so as not to confuse her. Remember, as she becomes more confident and uses fewer boxes, you can start to remove some of her early, "training" boxes.
The more, the merrier, specially if your rabbit is a bit of a slow learner, or is especially obstinate about where she wants her box(es) to go. As her habits improve, you can decrease the number of litterboxes.
Some rabbits love to kick their litter out of the box. You can get a covered litterbox (with a hood) to help solve this problem. You can also try experimenting with different litters. A second problem is that rabbits often back up so far in the litterbox that the urine goes over the edge. Again, a covered litterbox can solve this problem. Another solution would be to get a dishpan or other type of tub with much higher sides.
Get your rabbit into a daily routine and try not to vary it. Rabbits are very habitual and once a routine is established, they usually prefer to stick with it.
If your rabbit continually urinates in a spot where there is no litterbox, put his box where he will use it, even if it means rearranging his cage or moving a table in the living room. It is much easier to oblige him than to try to work against a determined bunny!