imo a bit of road work would help strengthen the pads and keep the nails down but if they are weak I'd look into the dogs diet  
 
  
do plenty road work his pads are ok, doesnt really have problem with them, his diet is quite good, mix of raw, veg, pasta, bones once weekly, egg twice a week, and markus muhle dry complete (very good food, not heat treated kibble). maybe its just in his breeding i dunno 
 
  
Maybe it's low on vitamin h or could have a bacterial infection in the nails? How bad are the nails?