The black crusts around your dogs lips are quite common especially in Westies. Westies are classic for skin allergies as many dogs of this breed have a genetic lack of internal immunity leading to a a condition called Canine Atopy.
Be sure your dogs food and water bowls are ceramic, stainless steel or glass. Try to avoid plastic and rubber feeding dishes and toys as both cause allergic reactions. Whatever your dogs mouth is coming into contact with is likely the culprit.
Ask your vet to run a thyroid blood panel as hypo or low thyroid levels lend themselves to allergies as well. A skin biopsy if needed will reveal underlying issues.
Try Vitamin E oil. Apply 1-2 times daily to black scabby lip lesions. This will help to heal and loosen them up so they fall off leaving healthy skin.
An organic or home made diet and a balanced, natural patented dog vitamin supplement geared to boost internal immunity would also be valid considerations. Should you want to follow up on this with me, that would be fine.
Dr Carol Osborne, DVM