lisset nyc, New York 11/19/2013 9:17:26 AM I had the same issue with my pup until a friend recommended petsspark. It is a natural product which is mixed in your pups food and it works miracles. It destroys the bacteria that causes this hard, dark, crusty tear stains. I did the whole treatment for my princess- 3 months, and it did not reoccur for about a year and a half.did the treatment again, has not come back since..completely safe. I recommend it!