We have no cement in our dog runs so most dogs have longish nails. Not sure as to any purpose for the nails other than the dew claws. Ours use them to help grip and turn bones and objects when chewing. They will also use a dew claw to grip you with. i.e., if standing up will hook one into your collar bone to hold you/them in place. Many also use their legs and paws similar to a cat and are quite dextrous with them. Most can open doors with handles or round door nobs, some can manipulate the chain and ring catches on our farm gates with paws - nails don't seem to come in to that action though. I usually clean the nailsl with a scouring pad and then wipe with baby oil. A quick wipe after than and any residiual dirt comes off.