Dog ear infections: causes, treatment, and why they keep coming back

What is actually going on in an infected ear?

A dog's ear canal is a deep, narrow, humid tube. When the lining gets inflamed it swells and makes more wax. That warm wet space suits bacteria and yeast very well. Vets call the result otitis externa, which just means inflammation of the outer ear canal.

What are the most common signs of an ear infection?

• Regular head shaking
• Scratching at the ear
• A bright pink or red ear
• Dark brown discharge. This is not a “dirty ear”: dark brown discharge is a classic sign that an infection is present.

It hurts more than most owners think

Of the common problems dogs are seen for, a sore ear is one of the most painful, and a dog does not have to cry for something to be hurting them. Most owners only realise quite how sore it was once it has been treated, and there was no way of knowing any sooner.

How common are dog ear infections?

Common enough that you can be quite sure you have not done anything unusual. Sore ears sit alongside dental disease, weight, overgrown nails and anal glands as one of the problems we diagnose most, and in any given year roughly seven dogs in every hundred are diagnosed with one.

Why does my dog keep getting ear infections?

Because in most repeat cases the infection is the second event rather than the first. Something inflames the ear lining, and the bacteria and yeast then move into the conditions that inflammation creates, so treating only the bacteria and the yeast means treating the consequence rather than the cause.

The things that start it off are usually whole-body, such as allergic skin disease, a hormone problem, or a disorder of the skin barrier itself, and sometimes it is something local instead, like a grass seed sitting in the canal. How likely a dog is to get sore ears tends to track closely with how much trouble they have with their skin generally.

Allergy is the one that catches most dogs, and ear and skin infections are among the commonest reasons an allergic dog flares. If your dog also licks their paws, rubs their face, or has flare-ups every spring, the ears may well be one symptom of a whole-body problem. That is a different conversation and a different plan, and one we are always happy to have with you.

Does my dog's breed or ear shape make this more likely?

Yes, though less than most owners assume and not quite in the way they assume. Swimming, humidity and the shape of the ear flap all add to the risk without actually starting the problem, so "he just swims a lot" is rarely the whole story, and it is well worth our working out together what started it.

Ear shape

Dogs with drop ears do tend to get more of these than dogs with upright ears, and a neat V-shaped drop ear is no safer than a long pendulous one, which surprises most people.

Breed

Some breeds do get more than their share, with Basset Hounds at the top of the list, followed by Shar Peis, Labradoodles, Beagles and Golden Retrievers. That last group matters a good deal around here, given how many poodle crosses live locally, though it is only a tilt in the odds rather than a sentence, and plenty of these dogs never get a single ear infection.

When should the ear be seen today rather than next week?

What does treatment involve?

There are four things, and they tend to go in this order.

1. Looking in the ear. We need to see how far down the inflammation goes, whether the eardrum is intact, and whether there is a grass seed sitting at the bottom of the canal, and it is not something anybody could see from home.
2. Finding out what is growing. A sample from the ear, looked at under the microscope, tells us whether we are dealing with yeast, bacteria, or both, and it changes the treatment, so it is the difference between a targeted plan and a guess.
3. Treating the ear, and then finding the cause. Medication settles this episode, and if it is the first one that may genuinely be the end of it. If it is not the first, the appointment that really matters is the one about why it keeps happening.
4. A follow-up recheck. It is really important to make sure the infection has resolved. If infection carries on under the radar, it can cause permanent ear damage that is much harder to treat later, and that sometimes needs more invasive treatment, such as surgery.

The plan we build is shaped around your dog rather than taken off a list, because what is growing, how sore the ear is, how deep the inflammation goes and what your dog has already had all change it. We will talk you through each step and stay alongside you until the ear is properly settled.

It really is worth finishing the whole course even when the ear looks much better after four days, because each flare thickens the canal lining a little more, and a canal that has thickened too far can turn a treatable problem into a surgical one.

What can you safely do at home?

Looking, and looking often, is genuinely the most useful thing of all, and ten seconds a week while you brush is plenty. Checking the ears as part of grooming catches build-up and early infection, along with fleas, ticks, matts, grass seeds and any sore spot or lump that we would want to see.

Looking is the part that helps, while routine flushing usually is not. A wipe of the ear flap with a dry cloth is perfectly fine, and if your own vet has already set up a cleaning routine for your dog then that is the one to stay with. Otherwise the canal is best left alone.

There are good and bad ear cleaners on the market. Where a dog does need one, we choose the cleaner best suited to that dog and the type of ear problem they have, so please ask us rather than picking one off the shelf.

If you see dark brown wax, please do not clean it away as dirt. It is usually a sign of infection or inflammation, and it is worth bringing your dog in.

What not to do

Please do not put anything down the canal that a vet has not prescribed for this dog, this time. That includes a leftover bottle from the last dog, and it includes treating a sore ear with olive oil, vinegar or peroxide suggested on a forum. If the eardrum is damaged, some of those go somewhere they cannot come back from, so we would much rather you rang us first.

What happens at Macquarie Veterinary Hospital

An ear appointment with us is a consultation, an examination of both ears, and a plan you go home with. If your dog has had more than one infection in a year, it is worth mentioning when you book, because that changes what we look for, which is not only what is growing today but what keeps letting it grow.

Common questions

Can a dog ear infection clear up on its own?

Sometimes the itch settles for a while, though the inflammation usually does not, and an ear left to sort itself out is the one that tends to end up chronic. If it has been going for more than a couple of days, we would like to see them.

Why does the smell come back within weeks of finishing the drops?

Because the drops treated the infection and nothing treated whatever started it off, which is exactly the pattern we would like to help you interrupt.

My dog only has one bad ear. Does that matter?

It is well worth mentioning to us. One ear consistently worse than the other raises the question of something physically in there, with a grass seed being the classic, rather than a whole-body cause.

What else in this series should I read?

If your dog also chews their feet or seems itchy all over, please mention it when you bring them in, because the ears and the skin are often one problem. Year-round parasite cover is part of the same picture, and we are happy to go through it with you.

The Macquarie Veterinary Hospital team

General practice and surgery, Macquarie Park

Medically reviewed by Dr Michael Stephen, BVSc, MVSc.