What does canker in horses ears look like?

Well, i couldn't find any pics of a horses ear with canker but hear is canker in the frog of a horses hoove:

It is :

1. Ulceration of the mouth and lips.
2. An inflammation or infection of the ear and auditory canal, especially in dogs and cats.
3. A condition in horses similar to but more advanced than thrush.
4. ## A localized diseased or necrotic area on a plant part, especially on a trunk, branch, or twig of a woody plant, usually caused by fungi or bacteria.
   1. Any of several diseases of plants characterized by the presence of such lesions.
5. A source of spreading corruption or decay.