Angels Eyes Tear Stain Remover for dogs and cats are specifically developed for pets to eliminate unsightly tear stains from the inside out. Angels' Eyes works to prevent tear staining by tying up circulating porphyrins. A porphyrin is a compound that reacts with light to produce a reddish brown stain to the medial canthus.Angels Eyes Tear Stain Remover ingredients will prevent your pet from contracting Ptyrosporin (Red Yeast) and bacterial infections which causes excess tearing and staining. Keep the tear stains away with just a sprinkle a day. Perfect for all breeds. Made in USA.