Sometimes a poor quality food can cause this, or allergies. My dog had this problem while he was in foster care, I told his foster mom what food I planned on feeding so she did the switch for me and by the time he came home his eyes had stopped running. My 1st step would be look at what food you feed and research its quality. You want meat as the first ingredient, very little grain, and no colorings. These are just basic things to look for, but I would suggest visiting the Dogster food forum, there is some great info there. Also, chicken seems to be a protein which a lot of dogs can become allergic to, and corn is another ingredient that can cause allergy issues in dogs.