hello mate,
the trouble is if they are running down the tarmac flat out after something it will wear any dogs pads and stoppers down, you wont stop that, but this might help harden pads and stoppers up, for normal hard graft,
get some surgical spirit from boots or a chemist, get some cotton wool aswell, soak the cotton wool with the surgical spirit, and dab it all over the pads, and in between the toes and nails, do it about 3 times a week, while your running your dogs,
cocker