I'm a dog groomer & have worked in a pet shop since i was 14! I have a staffordshire bull terrier & she's been my life line getting through treatment. My company through the day while my partner was working. & whenever i felt down she knew it was time to play ball to break my mood! Took some time to stop her leaping on me with my RIG tube though!
When i groom Bichons, westies or other white coated dogs, I usually cut the tear stain down and use a good remover. Regular application of petroleum jelly can prevent it coming back.