
I've never found anything that will completely remove the staining once it has started, though rinsing the stained area with a solution of bicarbonate of soda several times a day certainly seems to help. The only real "cure" is prevention.....doing all you can to stop the dog licking its legs and paws, by making sure they are clean
and dry after every walk etc, and by wiping the dogs chin after meals, drinks etc.
The stained hair will go at the next moult.
Hope this helps. :)