Swimmer's Ear in Dogs: Why Summer Swims Can Cause Ear Infections

Your dog spends an hour launching herself into the lake, has the best day of her life, and two days later she is shaking her head and rubbing her ear along the sofa. A dog ear infection after swimming is one of the most common summer problems we see in practice, and it is also one of the most preventable. This guide is for owners of water-loving dogs, particularly the floppy-eared ones, and covers why swimming triggers ear infections, what the first signs look like, what you can safely do at home, and the point at which your dog needs a vet.

Why does swimming cause ear infections in dogs?

A dog's ear canal is not a straight tube like ours. It runs downwards first, then turns inwards towards the eardrum, forming an L shape. Water that gets past the ear opening has to travel uphill to get out again, so some of it sits in the bend. Add body heat, a covering ear flap and thick hair, and you have a warm, dark, humid pocket.

The water itself is not really the villain. A healthy ear canal already carries small numbers of bacteria and yeast without any trouble. Persistent moisture softens and weakens the skin lining the canal, and once that barrier is disturbed, those normal residents multiply out of control. The usual culprits are staphylococci and the yeast Malassezia pachydermatis. In some dogs, especially those with a history of ear disease, Pseudomonas bacteria take hold, which are harder to treat and often traced back to environmental sources like water.

This is why veterinary dermatologists class moisture as a predisposing factor rather than a cause. It tips the balance in an ear that is already vulnerable. That distinction matters for you as an owner: if your dog gets an ear infection every summer, water is probably the trigger, but something else is likely making her ears susceptible in the first place.

Does it matter whether it is a pool, a lake or the sea?

All three can leave moisture behind, and moisture is the main problem. Natural water carries more bacteria and organic debris, and standing or slow-moving water in warm weather is the least ear-friendly option. Chlorinated pool water and salt water can be drying and irritating to the skin of the canal in a dog who swims daily. Rinsing salt, sand and silt off your dog after a swim, then drying the ears, covers all three situations.

One separate warning while we are on the subject of summer water: avoid any pond or lake with a blue-green scum or paint-like surface film. Blue-green algae can be rapidly fatal if a dog drinks or swims in it, and that risk is far more urgent than any ear problem.

Which dogs are most at risk?

Ear infections are common in dogs generally. A large UK study of over 22,000 dogs in first-opinion practice, published by the Royal Veterinary College's VetCompass programme, found that around 7 in 100 dogs were diagnosed with otitis externa (inflammation of the outer ear canal) in a single year. Breed and ear shape were the strongest risk factors identified.

Compared with crossbreds, the same study found notably higher odds in Basset Hounds (nearly six times), Chinese Shar Pei, Labradoodles, Beagles and Golden Retrievers. Dogs with pendulous ears and those with V-shaped drop ears had roughly 1.8 times the odds of dogs with erect ears. Chihuahuas, Border Collies, Yorkshire Terriers and Jack Russell Terriers came out lower risk.

Your dog is more likely to run into trouble after swimming if she has:

• Heavy hanging ears or V-shaped drop ears that seal the canal opening
• A lot of hair inside or around the ear canal, which holds water like a sponge
• Narrow ear canals, or canals already thickened from past infections
• Allergic skin disease, which is behind a large share of recurrent ear problems in dogs
• An underactive thyroid or other hormonal disease
• A history of ear infections, or a habit of swimming several times a week

Erect-eared breeds are not immune. A Labrador is a swimmer with drop ears and a well-developed set of glands in the canal, which is a fairly unlucky combination in July.

What are the signs of swimmer's ear in a dog?

Signs usually appear within a few days of the swim, sometimes within 24 hours. Look for:

• Head shaking, often repeated and forceful
• Scratching at the ear, or rubbing the head along carpet and furniture
• A yellow, brown or waxy discharge, sometimes with visible pus
• A sweet, yeasty or foul smell from the ear
• Redness or swelling of the ear flap and canal opening
• Holding the head slightly tilted to the sore side
• Flinching, yelping or pulling away when you touch the ear or scratch the head
• A quiet, flat mood, or reluctance to be handled, which in a stoic dog may be the only clue

Ear infections hurt. Dogs with a painful ear can become snappy when their head is approached, even dogs who are usually unflappable, so handle gently and warn children.

What should I do right after a swim?

Post-swim care takes about a minute per ear and prevents most of these infections.

1. Let her shake first: That reflex clears a surprising amount of water from the canal. Stand back and let it happen before you touch the ears.
2. Dry what you can reach: Wipe the inside of the ear flap and the fur just below the canal opening with a soft cloth, gauze or absorbent pad. Only go where your finger fits comfortably. Never push anything down into the canal.
3. Use a drying ear cleaner if your dog swims regularly: Ask your vet to recommend a veterinary ear cleaner with drying or astringent properties, and to show you the technique. Fill the canal, massage the base of the ear for a few seconds until you hear a squelch, let your dog shake, then wipe away the loosened debris and fluid from the outer ear.
4. Air the ears: Hold or gently fold the flaps back for a couple of minutes so air can reach the canal opening. Dry the fur behind and under the flap.
5. Keep the hair in check: Trimming excess hair from the ear opening and the inner surface of the flap improves airflow and lowers humidity. Ask your groomer or vet where to trim, and don't pluck hair out of the canal unless your vet has advised it for your individual dog.
6. Check the ears once a week during swim season: Lift the flap, look, and have a sniff. You are looking for changes from your dog's normal, which is the whole point of knowing what normal looks like.

What not to do

• Skip the cotton buds: They push wax and water deeper and can injure the canal or eardrum. Trauma from cotton swabs is itself a recognised predisposing factor for otitis.
• No rubbing alcohol, hydrogen peroxide or homemade vinegar mixes: These are all over the internet. On skin that is already inflamed or broken they sting sharply, and if the eardrum is damaged, alcohol and vinegar solutions can reach the middle ear.
• Don't overclean: Cleaning healthy ears daily irritates them and can set up the very problem you are trying to avoid. Clean after swimming and bathing, or on the schedule your vet gives you, not constantly.
• Never reuse leftover medicated drops: The prescription from last summer may be wrong for this infection, and using it can mask signs, drive resistance, or harm an ear whose eardrum has since ruptured.
• Don't force water out with a hairdryer: The heat risks burning thin ear skin.

When to call the vet

Book an appointment if your dog is shaking or scratching her ear for more than 24 hours, if you can see discharge or redness, or if the ear smells. Early otitis is straightforward to treat. Left for a week or two it becomes painful, deeper and much more stubborn, and repeated untreated episodes can permanently thicken and narrow the canal.

Contact a vet the same day, or an emergency clinic out of hours, if you see any of these red flags:

• Head tilt that stays, stumbling, circling, or falling to one side
• Rapid flicking eye movements, or a drooping face or lip on one side
• Sudden apparent deafness
• Blood in the ear discharge, or a badly swollen, closed-over canal
• Crying out when the ear is touched, or refusing food and hiding
• A ballooning, fluid-filled swelling of the ear flap, which can follow violent head shaking

Those signs suggest the middle or inner ear may be involved, or that the eardrum has ruptured, and they change both the treatment and the urgency.

What will the vet do, and how do I stop it happening again?

Expect your vet to look down the canal with an otoscope and check whether the eardrum is intact. Most will take a swab and examine it under the microscope, because bacteria and yeast need different medications, and there is no way to tell them apart by smell or colour. A culture may be sent off if the infection looks resistant, has recurred, or if rod-shaped bacteria such as Pseudomonas turn up on the slide.

Treatment usually means a thorough clean, then topical drops or an ointment, often combined with an anti-inflammatory to settle pain and swelling. Very sore or debris-packed ears sometimes need flushing under sedation. Two things make the difference between a cure and a rerun: finishing the full course exactly as prescribed, even once your dog seems comfortable, and going back for the recheck so your vet can confirm the ear has actually cleared rather than just quietened down.

If ear infections keep coming back, ask about the underlying cause rather than treating each flare-up in isolation. As the Merck Veterinary Manual puts it, otitis tends to return unless every contributing factor is addressed. In practice that means investigating allergic skin disease, food reactions, hormonal conditions such as hypothyroidism, or the shape of the canal itself. Dogs with chronic ear disease also do better with a written maintenance plan: which cleaner, how often, and what to do after swimming.

Most water-loving dogs can carry on swimming. Pause swimming while an ear is being treated, keep to the drying routine once she is cleared, and check the ears weekly through the summer. If your dog gets an infection after every single swim despite good aftercare, that is worth a conversation about her underlying skin health before you give up the lake for good.

The short version

Swimming does not have to cost your dog her ears. Dry them, air them, look at them once a week, and treat head shaking that lasts more than a day as a reason to ring your vet rather than something to watch a little longer. The infections that become miserable, long and expensive are almost always the ones that were left alone at the start.