In this episode of "The Knowledgeable Pet Owner," the hosts delve into the topic of tear stains and lick stains on dogs, explaining that these rust-colored marks are caused by porphyrins, a byproduct of red blood cell breakdown. The hosts highlight that these stains are often indicative of underlying issues, such as clogged tear ducts, eye irritation, or allergies, and emphasize the importance of consulting a veterinarian to address the root cause. While grooming can help manage the appearance of the stains, it cannot remove them completely, and certain products, including oral supplements, should be used cautiously. Owners are advised to maintain regular eye cleaning routines for their pets and be vigilant for any sudden changes that could point to more serious health concerns.