Chewing is a natural and necessary behavior for rabbits. In captivity, though, a restless rabbit's need to chew can quickly become destructive. A rabbit that's wandering around looking for things to chew may ingest stuff that's bad for it if left to its own devices for too long.
To help keep your rabbit from chewing on everything in sight—and potentially getting sick in the process—the key is to teach it what's appropriate for chewing and what's off-limits.
Why Do Rabbits Chew?
There's a biological reason for rabbits' constant chewing. Their teeth grow continually all their lives, and in the act of chewing, the teeth wear against each other, which keeps them trimmed.
In captivity, the main reason rabbits chew on things that aren't appropriate is boredom. If a rabbit spends a lot of time alone or doesn't have much stimulation, it seeks ways to entertain itself and/or get attention from its owner. Chewing on things is an easy way to accomplish both.
Given their biological urge to chew, rabbits in the wild nibble on a range of plants and grasses and burrow in their natural habitats. In captivity, rabbits still have the urge to chew, but how destructive they are is a combination of what they can get their paws on and how they've been trained.
How to Stop Inappropriate Chewing
Because your rabbit needs to chew, provide a variety of safe, chewable items. Branches from apple or willow trees, safe rabbit toys, untreated willow baskets and toys, untreated grass mats, and cardboard all make good chew toys for rabbits.
Providing multiple playthings gives your rabbit more choice, which can also help to keep boredom at bay. If you have different sizes and types of chew toys around, chances are that least one of them will satisfy your rabbit's craving to chew. Remember to provide your rabbit with a couple of safe chew toys in its cage as well.
Rabbit-Proof Your Home
Good rabbit-proofing takes away much of the temptation and opportunity for your rabbit to get into trouble. Don't give your pet free run of your home, at least not at first. Instead, designate a limited space and thoroughly rabbit-proof that space to make training easier.
Things like electrical wires are very dangerous for your rabbit, so you have to make sure there's no way your rabbit can get to them. Keep cords safely tucked out of the rabbit's reach, and use PVC cord protectors or tubing sold at hardware stores for cords that run along the floor.
Furniture and other belongings should also be protected. The less your rabbit can demolish, the less frustrated you'll be and the more smoothly training will go.
Supervise and Redirect
Your rabbit doesn't instinctively know that it's not allowed to chew on your furniture and other belongings, so you must teach it. When you're starting out with a new rabbit, this means that you must watch it carefully at playtime.
Make sure you start this training as soon as you bring your rabbit home so there's less opportunity for bad habits to develop. Whenever your rabbit tries to chew something it shouldn't, say "no" firmly (there's no need to yell) and clap your hands; then give it an appropriate chew toy.
Get a Second Rabbit
Destructive rabbits are often soothed by the presence of another rabbit. It's not a good idea to pair two unaltered (not spayed or neutered) rabbits, though. If you pair a male and a female, you're likely to get more rabbits; if you pair two males, they may fight.
Two unaltered females may get along fine, but the best option is to pair either two neutered rabbits or an unaltered rabbit with a neutered rabbit of the opposite sex.
Spay or Neuter Your Rabbit
Having your rabbit "fixed" is likely to erase much of its destructive behavior. You'll still need to provide plenty of toys that it can safely chew, but the rabbit will be much more chill about inappropriate chewing.
Try Rabbit Repellent Sprays
You can try applying a bitter apple spray (available at most pet stores) on inappropriate items that your rabbit likes to chew. Many rabbits don't mind the taste, though (and some even seem to like it), so this may be worth a try but isn't usually effective.
Avoid using any toxic chemicals in areas where your rabbit is likely to chew. Even though a chemical such as ammonia or bleach may act as a repellent, if your rabbit ingests it, it could prove to be harmful or fatal, depending on the chemical and how much was ingested.
Your rabbit will take its time to learn and will probably test you along the way, so be patient but consistent. Never hit or yell at your rabbit. If it keeps going back to your things instead of chewing on its own toys, put your bunny in a "timeout" in its cage for a few minutes.
Another alternative is to put your rabbit in an exercise pen (a collapsible, portable cage for dogs) for at least part of its playtime outside the cage, so you can relax on the supervision and training for a bit.
As your rabbit gets older and more settled, its chewing will become less of an issue, but consistency and patience right from the beginning are your biggest training advantages.