Cats scratch for two reasons. (a) To condition their claws. You will notice that they scratch off the old claws which can be seen lying at the bottom of the scratching post. (b) To leave a territorial message, which varies from “Keep out – this is my territory” to “Look at me. I am scratching.” This is a visual message and also a scent message from the scent glands on their paws.
(c) They have a need to top up an existing scent marked scratch area regularly with new scent. Therefore once they have a scratching place, they will continue to use it. This may be a way of updating the information conveyed by the first scratch!
The emotional need to scratch
If cats get anxious or stressed, they will scratch more or in new places. Using a water pistol on an already scratching cat will therefore make it even more worried. It may even turn from scratching to spraying. So NEVER punish or frighten a scratching cat.
Cats also use scratching as a way of asserting themselves and will scratch in the presence of another cat. They may take turns at the same post.
Finally some cats scratch to get your attention. They often will look at you as they start scratching. Saying No or shouting at it IS attention. If your cat is an attention seeker make sure you don’t ‘reward’ it. Walk out of the room when it scratches.