It may not be as simple as nails being too long other reasons could be food intollerance ,do you feed beef or beef of any sort be it food or bone ??? some dogs find beef makes thier feet itchy ,and they will bite to relive the itch . or has anything changed at home routine? new family member , new dog next door , some dogs will bite thier feet as a sign of anxiety , then it becomes like ocd they feel that they controll whatever it is they are nervouse about by biting thier feet .

__________________