Sadie had horrible problems with yeast in both her ears from August til we finally after trips to the vet almost every three weeks, numerous, creams/drops , oral antibiotics, and cleanings we got it cleared up in December. Hers got so bad they had to put her under and clean them, and found that one ear drum was ruptured. She has been back for check ups twice since then and everything is great.
I too have wondered about giving her yogurt to try and prevent future problems esp. since warmer weather is coming and she loves to swim in her pool!!!