The legs are the parts most in contact with the outside and after each walk it would be good to wash them: in winter to clean them well from the ice and salt that covers the streets and in summer for any ears, thorns or fragments .
If you notice that your dog is persistently licking a paw, it is best to go to a vet.
The nails must be kept under control especially if it is an apartment dog: on shiny tiles and floors they do not wear out and therefore they must be cut using an appropriate nail clipper or taking the dog to the vet.