Canker of Ear.

When internal, drop into the affected ear, night and morning, 3 or 5 drops of the following mixture:

Tincture of Hydrastis Canadensis 2 drachms.
Carbolic Acid (pure) ½ "
Glycerine, to make up to 2 oz.

If external, paint with the mixture the affected parts.

Fonte: Cats