What antibiotic treats ear infections in dogs?

That depends on the problem, but the most common medicines are Surolan and Otomax for bacterial and yeast infections which cause inflamation and terrible odor in the ears. If it's ear mites which look like wet coffee grounds in the ear revoulution or advantage multi are usually recommended. Make sure you clean the ears regualrly if its prone to infections with a routine ear cleaner. Always clean the ears daily while the dog is on ear drops.