Ear infections in dogs: causes and treatment

Ear infections are common, painful and easy to underestimate in dogs. Typical signs include head shaking, scratching, odour, redness and discharge. Around 10 to 20 per cent of dogs are affected at least once in their lives. Problems often become chronic because owners try home remedies or ear drops before the underlying cause has been identified.

Types of ear infections

Not every ear infection is the same. The name depends on which part of the ear is affected.

Otitis externa affects the outer ear canal, the area between the ear flap and the eardrum. It is by far the most common form. The dog scratches, the canal looks red and discharge is common. With prompt treatment, it usually settles well.

Otitis media affects the middle ear behind the eardrum. It usually develops when otitis externa is left untreated or treated too late, allowing the infection to spread through the eardrum. Pain is usually much worse, and the dog may barely tolerate being touched around the head.

Otitis interna involves the inner ear, where the balance apparatus sits. This form is rare but serious. Dogs with otitis interna often show vestibular signs such as loss of balance, walking in circles or falling to one side. Without treatment, permanent damage to hearing or balance can follow.

These forms can overlap. What starts as mild redness in the outer ear canal can spread deeper within a few weeks.

Typical causes

Ear infections rarely have just one trigger. Several factors often come together:

Moisture is one of the biggest risk factors. Water left in the ear canal after swimming or bathing creates a warm, damp environment where yeast and bacteria multiply quickly.

Anatomy matters too. Dogs with floppy ears have poorer air circulation in the ear canal than dogs with erect ears. Breeds with narrow or heavily haired canals trap moisture even more easily.

Allergies are often overlooked. Food allergy and environmental allergy, such as pollen or dust mites, can trigger inflammation in the ear canal or make existing problems worse. If the otitis keeps coming back, allergy testing is worth discussing.

Yeast (Malassezia) normally lives on canine skin. When the ear environment is out of balance, it can overgrow. Typical signs are a brown, crumbly discharge and a slightly sweet smell.

Bacteria such as Staphylococcus or Pseudomonas can start an infection or worsen an existing one. Bacterial otitis often produces yellow or green purulent discharge.

Ear mites (Otodectes cynotis) are most common in puppies and young dogs. They cause intense pruritus and a dark brown, coffee-ground-like debris in the ear. Mites are contagious and can spread to other animals in the home.

Foreign bodies such as grass awns can get into the ear canal and trigger acute inflammation. This happens especially in summer after walks through tall grass. Because grass awns have barbs, they can migrate deeper into the canal. Sudden, violent head shaking after a walk is a classic warning sign.

Recognising symptoms

Some signs are obvious, others are easy to miss. Watch for:

• Head shaking: Frequent and intense, especially after waking up
• Scratching at the ear: The dog rubs its ear on furniture or scratches with a hind paw
• Odour: A musty, sweet or purulent smell from the ear
• Redness and swelling: The inside of the ear flap or the ear canal is red
• Discharge: Brown, yellow or greenish, crumbly or purulent
• Pain response: The dog pulls its head away when you touch the ear
• Head tilt: The head is permanently tilted towards the affected side
• Behavioural changes: Restlessness, loss of appetite, the dog seems subdued

If symptoms affect only one ear, a foreign body or localised infection is often involved. If both ears are affected, allergy or another broader cause becomes more likely.

When to see the vet immediately

Most ear infections respond well when treated early. With the following signs, do not wait:

• Balance disorders: The dog staggers, falls over or walks in circles. This suggests inner ear involvement.
• Severe pain: The dog won't let anyone touch its head, whines or reacts aggressively to contact.
• Neurological symptoms: Eye twitching (nystagmus), tongue hanging out on one side, uncoordinated movements.
• Heavy purulent discharge: Greenish or bloody pus may indicate a severe bacterial infection.
• Fever and loss of appetite: Signs that the infection is spreading.
• Sudden head shaking after a walk: This points to a possible foreign body in the ear canal.

In these cases, every hour counts. Otitis interna or a lodged foreign body can cause permanent damage if treatment is delayed.

Diagnosis and treatment

Why the vet is essential

Without the right diagnosis, targeted treatment is impossible. Off-the-shelf ear drops may dampen symptoms for a while, but they do not tell you whether the problem is yeast, bacteria, mites, a foreign body or allergy. If yeast is the cause, antibiotics will not help. If mites are involved, the dog needs an antiparasitic. If allergy is driving the otitis, it will keep coming back until the allergy is addressed.

What the vet does

Otoscopy: The vet uses an otoscope to examine the ear canal and eardrum. This shows how far the inflammation extends and whether a foreign body is present.

Cytology: A sample from the ear is examined under the microscope. That shows whether yeast, bacteria or mites are involved.

Bacterial culture: In recurrent or severe cases, a culture is grown to identify the exact pathogen and test which antibiotics are likely to work.

Treatment options

Treatment depends on the cause:

• Ear cleaners: In mild cases, professional cleaning followed by a suitable ear cleaner may be enough.
• Antifungals: For yeast infections, for example clotrimazole or miconazole.
• Antibiotic ear drops: For bacterial infections, ideally chosen with culture results in mind.
• Antiparasitics: For ear mites, for example selamectin or moxidectin. All animals in the household should be treated.
• Anti-inflammatory medication: Corticosteroids in ear drops can reduce swelling and pruritus.
• Allergy treatment: If allergy is the cause, the trigger has to be identified, for example with an elimination diet or allergy testing. Otherwise the otitis will keep returning.
• Surgery: For foreign bodies, polyps or chronic cases that do not respond to treatment.

Treatment usually lasts 7 to 14 days. Finish the full course even if symptoms improve after a few days. Chronic ear infections may take much longer.

What you can do at home

Ear infections belong in veterinary hands. You can still do quite a lot to prevent them and support treatment.

Check regularly: Look inside the ears once a week. Healthy ears are pale pink, dry and free from odour. Pick up changes in colour, smell or discharge early.

Dry ears after swimming: Gently dab the ear flap with a soft cloth. Do not push water down the canal. In dogs that swim often, a vet-recommended ear cleaner after bathing can help bind residual moisture.

Do not use cotton buds deep in the ear: You can carefully clean the ear flap and the visible part of the canal. Never push cotton buds or other objects further in. That only drives debris and wax deeper and can damage the eardrum.

Apply ear drops properly: If your vet prescribes them, gently lift the ear flap, place the drops into the canal and massage the base of the ear so the product spreads. Then let the dog shake its head.

Check for grass awns after walks: In summer, after walks through meadows and fields, inspect the ears for grass seeds. Remove anything visible with care. If something is deeper in the canal, go to the vet.

Breeds at higher risk

Any dog can develop an ear infection, but some breeds are anatomically more at risk.

Dogs with floppy ears such as Cocker Spaniels, Basset Hounds, Beagles, Golden Retrievers and Labradors have restricted airflow in the ear canal. Heat and moisture build up under the hanging ears.

Dogs with hairy ear canals such as Poodles, Schnauzers and some terriers have dense hair growth in the canal. That hair can reduce airflow and trap wax.

Dogs with narrow ear canals such as Shar-Peis or Bulldogs may have canals where moisture and secretions build up easily.

If your dog falls into one of these groups, regular ear checks are especially worthwhile. Ask your vet whether routine ear cleaning makes sense.

Prevention

Many ear infections can be prevented, or at least made less frequent:

• Check ears briefly once a week: look, smell, feel
• Dry ears after swimming or bathing
• Ask the vet whether thinning the ear canal hair would help
• Have allergies investigated if the infection keeps recurring
• Inspect the dog for grass awns after meadow walks
• Don't put aggressive cleaning agents or home remedies in the ear
• For susceptible dogs: use a vet-recommended ear cleaner as needed

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