The scientists have still not found any one definite answer for the reason behind cats scratching furniture. However, different studies have come out with different reasons behind cats’ scratching furniture. The first thing to keep in mind is that cats do not scratch furniture to spite you but they have been bestowed with this instinct to scratch by nature which obviously we can not stop.
Cats scratch furniture for the sake of communication. By scratching furniture or other standing objects cats want to communicate to other cats and people where they are and what they are up to. A typical cat chooses very few items to scratch on and keeps returning to them for the purpose of communication.
When the cat scratches on the furniture, it leaves a clearly visible scar which can be easily seen by other cats. Along with the visual clue, the cats also give olfactory clue as the scratching leaves a distinct smell of cat’s claw on the piece of furniture. That is the reason why your declawed cat also keeps scratching on that piece of furniture.
The other possible reason is that cats scratch furniture because they want to announce that they are the master of that territory or they simply want to announce that they live in that particular area. Cats also scratch furniture while playing and for relieving stress. By scratching the furniture, they also stretch their limbs.
If you want to save your furniture from being scratched you can simply erect a few scratching points in home which are the size of a standing cat on hind legs, as cats like to scratch things which are tall enough for their height and on which they can put their fore limbs and scratch.