Your dog’s ear infection may clear up, only to return weeks later. That does not mean you have done anything wrong. Recurring ear infections often happen because an underlying problem (such as allergies, an ear-canal condition, or, less commonly, a hormone disorder) has not been addressed. Finding that cause is an important step toward breaking the cycle.
An outer-ear infection, or otitis externa, is inflammation of the ear canal. Bacteria or yeast may overgrow in an inflamed ear, but their presence does not always explain why the problem began. A veterinarian can examine the canal, check a sample under a microscope, and help identify what is driving the irritation.
What dog ear infection symptoms should you watch for?
Some signs are easy to spot. Others may look like a harmless habit at first. Check your dog’s ears regularly, especially if they have had an infection before.
Common signs include:
- Frequent head shaking
- Scratching at one or both ears
- Rubbing the side of the head on furniture, carpet, or the floor
- Redness, swelling, or warmth around the ear opening
- A noticeable or unpleasant odor
- Discharge or more wax than usual
- Sensitivity or pain when you touch the ear
A head tilt, loss of balance, circling, or unusual eye movements can signal a more serious problem involving the middle or inner ear. Contact a veterinarian urgently if you notice these signs, or if your dog has severe pain, facial drooping, or seems suddenly unable to hear normally.
What can ear discharge tell you?
The color and texture of discharge can offer clues, but they cannot reliably tell you which organism is causing the problem. Yeast, bacteria, ear mites, and mixed infections can look alike. Avoid choosing drops based on appearance alone.
For example:
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Dark brown, waxy or greasy discharge can occur with yeast overgrowth, but it is not proof of yeast.
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Yellow or pus-like discharge may occur with bacterial inflammation.
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Green, slimy discharge or a particularly strong odor may raise concern for certain bacteria and deserves prompt veterinary attention.
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Dark, coffee-ground-like debris can also occur with ear mites, especially in cats, but a veterinarian needs to confirm the cause.
A quick exam and ear-swab test are more dependable than color. The right treatment depends on what is found and whether the eardrum is intact.
Why are some dogs more prone to ear infections?
Ear shape, hair, moisture, and the condition of the skin lining the canal can all affect ventilation and drainage. Some dogs are predisposed, but any dog can develop an ear infection.
Breeds and features that may raise risk include:
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Floppy-eared dogs, including Golden Retrievers, Cocker Spaniels, and Basset Hounds. The ear flap can reduce airflow around the canal.
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Dogs with hairy ears, including Poodles and Schnauzers. Hair or a narrow canal may make it harder for moisture and debris to clear.
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Dogs who swim often or regularly get water in their ears.
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Dogs with skin allergies, which can cause inflammation around the ear and elsewhere on the body.
These traits do not mean your dog will inevitably have ear trouble. They simply make regular checks and a veterinarian-recommended care routine more useful.
Why do dog ear infections keep coming back?
Bacteria and yeast often take advantage of an ear that is already irritated. If the primary cause remains, the canal may become inflamed again, creating another opportunity for microbial overgrowth.
Could allergies be the underlying cause?
Allergies are a common factor in recurring ear problems. Environmental allergens, such as pollen or dust mites, and food-related reactions can trigger itchy, inflamed skin. In some dogs, the ears are one of the first places you notice a problem. Paw licking, face rubbing, or recurring skin irritation may also be present.
Your veterinarian can assess whether allergy is likely and discuss a management plan. Allergy testing may help guide certain decisions, such as allergen-specific treatment, but it does not replace a veterinary exam or an ear-swab test. For more background, see our guide to understanding and managing environmental allergies in pets.
Can thyroid disease play a role?
Hypothyroidism, a condition in which the thyroid gland does not produce enough hormone, can affect the skin and may contribute to recurrent skin or ear problems. It is one possibility, not the only explanation, and ear infections alone do not diagnose thyroid disease.
Your vet may consider bloodwork if your dog has repeated infections alongside signs such as low energy, unexplained weight gain, hair thinning, or increased sensitivity to cold. Learn more in our article on hypothyroidism in dogs.
What else can keep an infection going?
Moisture from swimming or bathing can encourage irritation. Other possible causes include ear mites, a foreign object such as a grass awn, a skin condition, or changes in the ear canal after repeated inflammation. In persistent or one-sided cases, a veterinarian may look for less common causes, including a growth.
What tests does a veterinarian use?
Veterinary diagnostics help distinguish an infection from other causes of ear irritation and guide treatment. A typical evaluation may include:
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An otoscope exam: The vet uses a lighted instrument to look into the canal for swelling, debris, foreign material, growths, or changes to the eardrum. If the ear is very painful or blocked, examination may require additional steps.
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Ear cytology: The vet collects a small sample, often with a swab, and examines it under a microscope. This helps identify yeast, bacteria, and inflammation. The vet may sample each ear because they can have different findings.
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Culture and sensitivity, when appropriate: For severe, recurring, or poorly responsive infections, a lab culture may help identify bacteria and which medications are more likely to work.
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Bloodwork or an allergy workup for selected chronic cases: These tests do not diagnose an ear infection. They may help investigate an underlying concern, such as suspected thyroid disease or allergic skin disease.
If your dog has a painful ear, do not put leftover medication or an ear cleaner in it unless your veterinarian says it is safe. Some products can harm the ear if the eardrum is damaged, and the wrong treatment may delay the right care. An at-home dog health test may be useful for other indicated lab needs, but it cannot replace an otoscope exam or ear cytology.
How can you help prevent another flare?
Prevention depends on the cause and your dog’s history. Once the infection is treated, ask your veterinarian what routine is right for your dog. Healthy ears do not always need frequent cleaning, and overcleaning can irritate the canal.
Helpful steps may include:
- After swimming or bathing, gently dry the visible outer ear with a soft towel.
- Use only a veterinarian-recommended ear cleaner, and follow the instructions for how often to use it.
- Never push cotton swabs or other objects into the ear canal.
- Avoid vinegar, alcohol, hydrogen peroxide, or other home remedies unless your vet specifically recommends a product.
- Complete prescribed treatment for the full duration, even if the odor and scratching improve.
- Attend recommended rechecks. Your vet may need to confirm that the infection has cleared and that the underlying cause is being managed.
Stop cleaning and contact your vet if your dog seems painful, the ear becomes more red or swollen, or symptoms worsen. Seek urgent care for a head tilt, balance problems, facial drooping, or severe pain.
When should you call the veterinarian?
Make an appointment if you notice persistent head shaking, scratching, odor, redness, discharge, or discomfort, especially if these signs have returned after treatment. Prompt attention can help your dog feel better sooner and reduce the risk of chronic changes in the ear canal.
The goal is not just to quiet the next flare. It is to understand why it keeps happening. With an exam, appropriate testing, and a plan for any underlying allergy, moisture issue, or health condition, you and your veterinarian can work toward fewer painful recurrences.
