HI this is DRB and I am very sorry to hear about this and I see this ALL the Time.......your dog has food allergy and that is why her ears are chronic and not healing. Here is what you need to do:
Find a veterinary dermatologist which I can help you with, just say the word....
1. Your dog will need a hypoallergenic dog food like Prescription diet DD and also Purina HA is another option
2. The ears will need to be treated for several months to rid the infection and your dog will have to stay o hypoallergenic food forever
3. Once ears are cleared, there will need to be some type of maintenance.
4. your dog may have to go on apoquel allergy drug also
Say the word and I will help you find a dermatologist that can get your dog healed up.
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Please note that the information I provide is intended as general information only and not intended to replace the advice of your veterinary professional.