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Bacterial Ear Infections in Dogs: Causes, Signs, Treatments

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close up of the inside of a beagle dog's ear

Ear infections are an incredibly common issue that we see in the vet clinic, with many dogs becoming ‘repeat offenders’. Having some knowledge on this condition can ensure an owner knows how to best help their dog. This can mean preventing infections but also managing them correctly when they do occur.

Ear infections won’t always be caused by bacteria, though this is one of the most frequent causes. Other potential causes would include fungal overgrowth or ear mites.

What causes bacterial ear infections?

There are a number of factors that can contribute to these infections. These include:

  • Underlying allergies. Certain dogs have allergic dermatitis and will react to things like food ingredients, dust mites and pollen. Some breeds are more likely to develop allergies, including Frenchies, Labradors and Spaniels. As well as pink and itchy skin, allergies can lead to blocked anal glands and bacterial ear infections.
  • Getting wet. Water in the ear canals creates a nice ‘home’ for bacteria to multiply. After a dog takes a bath, goes to the groomer or has a swim then we want to use cotton wool to thoroughly dry out their ear canals.
  • Ear shape. Did you know, those with floppy ears are much more prone to bacterial infections? This includes breeds such as the Spaniel, Dachshund and Golden Retriever. Their floppy ears mean the ear canal is not well ventilated and it quickly becomes humid and moist. This leads to the perfect environment for bacterial overgrowth.
  • Hormonal disorders. Some hormonal disorder such as an underactive thyroid or Cushing’s disease can make a dog more prone to skin and ear infections. Owners would also notice other signs of an endocrine balance, such as a change in the dog’s energy or thirst levels.

What signs does a dog with an ear infection show?

Some of the classic signs of a bacterial ear infection would include head shaking, ear rubbing or scratching and a foul smell from the ear. When an owner looks inside the canal, they may notice that it looks red and swollen. They may also see thick wax, brown debris and/or pus.

As the infection progresses and the dog gets more uncomfortable, they may develop additional signs such as lethargy, a reduced appetite and even a fever.

How can I help my dog from home?

It can help to regularly remove wax and debris from your dog’s ear using an ear cleaner and cotton wool or pads. For those prone to waxy build ups, this needs to be done every 1-2 weeks. Some dogs will not need their ears cleaned.

Drying ear canals after they get wet is really important and can go a long way towards preventing infections.

Monitor your dog’s ears regularly so if they start to develop signs of an infection you can bring them to the vet for assessment promptly. The sooner an ear infection is treated, the quicker it will resolve.

What will the vet do for my dog?

Your vet will check your dog over and look inside their ear. They should ensure the eardrum is intact, check for polyps or foreign bodies and swab the discharge to check for the presence of any bacteria, fungi or mites.

vet looking at a dog's ear

Once your vet knows what type of infection they’re dealing with, they’ll start your dog on the most appropriate medicine. This may include some oral anti inflammatories and some antibiotic ear drops. Any wax or discharge will be removed.

For severe or persistent infections, your vet may send a swab to the lab for analysis, to check for resistant bacteria. They may also schedule an ear flush under anesthetic.


  • Dr. Linda Simon, Veterinarian

    Dr Linda Simon (MVB MRCVS) has 10 years of experience as a veterinarian. She is a veterinary surgeon with a special interest in geriatric patient care, dermatology and endocrinology. She is a member of the British Royal College of Veterinary Surgeons. She graduated top of her class from UCD School of Veterinary Medicine in Dublin in 2013. Linda has also worked as a locum vet in a range of clinics, including 24 hour emergency clinics and busy charity clinics.

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