The benefit of yogart as a probiotic in dogs is in doubt. The idea that a culture of lactobacillis+streptococcus placed in the intestinal tract could somehow make a difference in the ecological system of the ear is... well let's just say the ear bone is not connected to the stomach.

If you wish to attempt to control repeated chronic ear infections then a 1/3 white vinegar to distilled water solution cotton ball swabbing into the ears 2X daily is the ticket. The only problem is remembering to do it faithfully!

Otherwise keep a tube of Ottomax on hand so that you can treat when it's obvious an infection is present.