My shih tzu was bad for that. I changed her food to a higher quality food, and I wash her face every week really well when I bathe her. I also wipe her face every day with regular old toilet paper. Changing the PH balance of your dog helps too. Some people use apple cider vinegar or tums in the water. I haven't tried that though. I tried something called Angel Eyes, but I wouldn't be bothered with the daily facial bleaching.