One can and should trim claws, especially if the cat is old and not very active; if you don't, the claws become curled over, very thick and cause problems walking. I trim just a smidgeon off our cats' claws (the very sharp bit) It's quite true that it's illegal here in UK to de-claw a cat, rightly so. I feel that if one has animals (of any kind) one has to learn about their needs and habits and adapt to them. Dogs are more trainable, but cats are not. I hate for instance to see dogs shut in a cage for most of the day, barking their heads off. They need to go out for a long walk. Cats need to go out to explore, mark their territory and sniff about. Any restriction on these needs is unkind.