As long as it is still open and bleeding, I would continue with the saline washes. Feet are slow to heal, as they are very flexible so wounds will re-open, and walking rubs against them too.
Just make sure that it isn't swollen or red. You might want to keep him confined to the garden for a few days, if you are walking on concrete that will open it back up. He's better off on grass with a good flushing afterward. If bleeding in the house is a problem you can try bandaging the foot. (Good luck keeping it on
)
I had a Doberman who had this happen, he eventually lost the nail, but the healing was pretty uneventful, they usually do fine