Declawing a cat is a major surgical procedure, performed under general anesthesia. It is actually amputation of the last joint on each toe, not a simple removal of the claw itself as many are led to believe.
Cats walk on their toes, unlike most mammals who walk on the soles of their feet. Their musculature, joints, tendons and ligaments are all designed to distribute their body weight to their toes. The claw is not a nail like human fingernails or toenails. It is actually a part of the last bone in a cat's toe. If you were to "declaw" a human in the same way a cat is declawed, you would be amputating all 10 fingers at the last joint!
There is a real possibility of complications after any major surgery, and declawing is no exception. There is the possibility of hemorrhage, infection, extreme pain and bone chips.
There is also the possibility of nerve damage.
The cat can become withdrawn, distant, fearful and/or aggressive, and often start biting, as this is the only means of defense left to them. Occasionally the cat will stop using the litter box because immediately after surgery it was painful to scratch in the litter box, and now they associate that pain with the litter box
Some countries have made declawing cats illegal. They have considered it an abusive practice. Getting a good scratching post for your cat and teaching him to use it will help save furniture. Your cat needs his claws for defense and hunting if he ever gets lost. Look for alternative methods to save things from your cat’s claws—just save your cat’s claws. He will be happier and healthier from the choice and you will be happier knowing your feline friend has what he needs to survive.