My cat is always scratching at the doors and windows. He's around 3 years old and is in inside cat, we've had him for about a year.
I thought it might be because he wanted outside so I've got a harness and tied him up for an hour or so a few times but that only seems to make him crazier when he's inside.
Any thoughts on this problem?
It does indeed sound like he wants to go outside. It sounds like you have access to outside space, so the best solution would be to let him go outside. Remember that cats are not naturally indoor creatures, and that they have a pathological hatred of closed doors!
Is your cat's nails too long? Do you have any scratching post in house?
A natural behavior of cats is to keep their nails in shape by using scratching posts. They are readily available in various pet shops and online shopping sites and do not cost much.
Alternatively you can try clipping your cat's nails with a nail cutter. Do see a youtube video about how to do so before doing.
