All dogs will have some discharge at the corners of their eyes. It's perfectly normal to need to clean a bit of light gray matter from their eyes once or twice a day. But owners take note: if the color of the discharge is yellow or green, or if buildup appears frequently, you should consider asking your veterinarian to test your dog for dry eye.
Pets visit veterinarians for many reasons, but allergies are one of the most common reasons (1, 2). Because of this, many veterinary health insurance policies will not fully cover veterinary allergy visits.