I had terrible trouble with ear mites in my dogs, we just couldnt get rid of them, so in the end teh Vet, realised that the ear wax in Cloe's ears must be protecting soem from the medication, oh it went on for weeks, with cross infection not just with my dogs but with other families of cavaliers that visit us, in the end the clearing of the wax saw the end to persistant ear mites.