There are different causes for dog tear stains, and several remedies depending on the cause. It's important to note that tear stains can be the result of a more serious problem, and in many cases simply removing the tear stain will not prevent future stains from occuring without continued treatment. The following are the 5 most common causes:

Excess Tearing
Excess tearing (or epiphora) is usually a response to an environmental irritant and may be a sign that your dog has allergies. The discoloration is actually caused by bacterial and yeast growth.