Scratching of Furniture
Cats scratch objects in their environment for a variety of reasons. Scratching stretches out the muscles, especially after a nap. It removes the outer sheath of the nail. Scratching marks the area with the scent from the gland in the cat's paws. And it can just be fun! Because scratching is such a vital behavior for a cat's well-being (even declawed cats "scratch" surfaces) it should not be punished. Rather, the cat should be taught to scratch on a scratching post or other acceptable (to the human) place.
Most cats prefer to scratch on vertical surfaces but if your cat is clawing the carpet or armrest of the sofa you will need to provide a horizontal scratching surface. Regardless of what you buy, be sure it is sturdy enough to not move while the cat is scratching it. Posts should be tall enough to provide plenty of opportunity for the cat to stretch. Place the post/pad near the item your cat scratches the most or near her favorite sleeping spot (in a larger home or a household with multiple cats, more than one scratching surface may be necessary). Spraying or rubbing it with catnip or attaching a toy to the post often helps to encourage its use by the cat.
Preventing your cat from scratching on off-limits areas is important. Cover the spots your cat has been scratching with double-sided tape or bubble wrap. Spraying the furniture with Feliway®, a synthetic pheromone, can help reduce scratching that is done to mark. If you catch your cat attempting to scratch the furniture, interrupt her by making a noise (but not so loud as to scare the cat) and then take your cat to the scratching post and encourage your cat to use it by dragging a toy up the side. Do not place your cat's paws on the post and attempt to make your cat scratch. Most cats don't enjoy this and you could form a negative association with the scratching post.
Reward your cat with praise any time you see your pet using the post. In the initial stages of training, a treat or other special reward should help to ensure that your cat chooses the post again in the future.