Dog scratching ear for months after potato. Is it an infection?

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Buddy. I would think that you would have noticed problems right after the foreign body entered the ear. He would have been scratching at the ear a lot, shaking his head, rubbing that ear on the floor, etc. If you are only noticing problems now I would think more about an allergic ear problem, water in the ear, a different foreign body in the ear, or a primary ear infection. I would advise that if he still scratches the ear and the signs are persistent, you should have your veterinarian check Buddy out. We are in a time of high allergies in dogs and ear problems can be a big part of the clinical picture, even if it is only one ear. Your vet can take a detailed history and do a complete physical exam/otoscopic exam of the ears. They can take a sample of discharge from the ear and look at it under the microscope looking for ear mites or signs of infection (bacteria, yeast, possibly some white blood cells, etc.) Your vet can then prescribe a treatment based on those results. This often involves an ear medicine, possibly some antibiotics, anti inflammatory meds, pain meds, etc. Good luck with Buddy.