I'm a bit embarrassed to say this, but our dog has a persistent ringworm problem. Several times throughout the years, we'd apply Viaderm or something that can be bought from our local vet. Then, when she'd (it's a she) stop itching so much and we'd used up all her Viaderm, we'll stop treating her. Then her ringworm comes back. I guess through the years, her number of spots with infection has only increased.
What I'm thinking now is to treat her for good. We'd shave her bald then apply the Viaderm for weeks. We've tried shaving her last year (or was it 2 years ago??), but it was a tedious task -- it's a thick curly fur, and you could hardly call her bald. So I was thinking of using a sheep shear.