I not sure how reliable this info is, but I heard that puppies sometimes have their dew claws removed soon after birth without anesthetic because there are not yet any nerves in this area, so they do not feel anything.
When my dog had hers removed she ahd to be put under anesthetics and it required 3 stitches. I don't think it was all that painful for her, but the anesthetic make her sick and she wasn't herself for a few days, However, 3 days later, she had riped out all of her stitches and was running aorund like normal again.