See your vet
What it can look like. A general, vet-reviewed example — signs vary and this is not a diagnosis. When in doubt, ask your vet. 
Recurring ear infections in dogs
Clinical name: Otitis externa
Red, swollen, sometimes smelly ear canals with discharge.
Where it shows upears
Typical patternOne or both ears.
Linked allergy typesEnvironmental (atopy) · Food allergy
Food vs environmentalRepeated ear infections, especially both ears, can point to food.
What you can do
Recurrent ear infections are one of the strongest allergy clues — see your vet and ask about diet.
Don't confuse it with
Other causes a vet will want to rule out: ear mites, foreign body, yeast.
This is educational information, not a diagnosis or treatment plan. Always see your veterinarian about your dog's health.
Related signs
Ear discharge & odorKeep an eye on it
Waxy, brown or yellow discharge with a yeasty or sour smell.
Head shaking & ear scratchingKeep an eye on it
Repeated head shaking and pawing or scratching at the ears.
Swollen ear flapSee your vet
A soft, fluid-filled swelling of the ear flap, caused by violent head-shaking.