...my comet was recently treated for an ear infection, with Tresaderm. He had the same brown gunky discharge that you describe. The problem for my yorkie was that he was scratching his ears alot, which caused the irritation. My comet has floppy ears so I try to check his ears frequently , due to the moisture build up because they are floppy.
If this substance is unusual for your Sammi, you should call the vet, and have them make sure that the ears are not infected. Bacterial infections can spread fast in small yorkies. You should check it out asap. Please keep us posted!
Cometsmom
