Regular ear cleaning should always be part of your routine with your dog. Dogs with upright ears, need less attention than Dogs with floppy or hairy ears, but still regular and thorough cleaning is recommended at least once weekly with all breeds. You can put a few drops of an ear cleaning solution made for dogs on a cotton ball and then, massage the base of the ear and try to clean down the entire length of the ear canal. Your vet can be very helpful in demonstrating how this can be done, and some vets will also pluck the ears of hairy dogs for a small fee, to help you prevent the promotion of bacteria in your dogs ears.
If discharge appears on the cotton ball, or if the ear canal seems red, or sore, then your dog could have an ear infection. Ear infections can be painful and extremely uncomfortable for your dog, so it is best to consult your veterinarian as most infections are easily treated if caught early.