How does your dog react to getting wet? Is he a nose and chin rubber. Does he tend to lick his feet a lot?
When Phoebe was first here - she came at 15 months - she would take a drink and then rub her face on the carpet rabidly. She hated going out on wet grass and she chronically had ear infections. It progressed to inflamed looking skin on the anal opening and she started to scoot a lot. It was a yeast infection. Vets wanted to treat her for allergies with foods and prednisone. She even went to the veterinary dermatologist at Guelph were she was put on an anti rejection drug. She had demodectic mange problems so she lost the hair around her eyes several times and was treated with ivermectin. When she first came she didn't have a coloured hair on her body - westies go red as soon as they start licking at themselves. Within a month she had red feet, red around the mouth, no hair around her eyes, hair loss on her body, broken hair on her chin, ear infection and couldn't leave herself alone. Too many stressors at one time caused her immune system to deplete enough for the yeast and demodex to become a problem. After many different vets, a few years, and a couple of thousand dollars, we turned to a person that had become knowledgeable in the use of alternative treatments. Presto - Phoebe is healthy, happy, no ear problems or itching even after getting into cat food, great coat etc. and just try to get her in out of the rain if there is a squirrel or a chipmunk about. If your dog isn't swimming or otherwise getting moisture into it's ears and it gets recurring ear issues then I would suggest that you have more than ear infection. There is something underlying that is making it difficult for the skin to remain healthy.