Bless you for taking in this poor baby and giving him a loving home!
I wouldn't wash him too often or it could dry out his skin & cause itching. I have seen some mouthwash spray for dogs, but I've never tried it. I think you're on the right track, just keep doing what your doing.
Thank you!
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He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion. -- Author Unknown