In normal animals, tears are constantly produced and drain out through small ducts in the eyelids. The ducts empty into the nose. In animals with blocked ducts, the tears overflow the lids and run down the face. Tear staining is usually caused excessive tear production. The tearstains themselves are reddish-brown streaks under a dog’s or cat’s eyes. The condition is much more prevalent in certain breeds (for example, the Maltese, the Lhasa Apso, and the Shih Tzu), and is much more obvious in animals with light-colored coats. While tear staining is typically......