How do dogs get ear infections?

Ear infections are one of the most common reasons dog owners bring their pets to the clinic; they cause real discomfort, can make active dogs stop enjoying swims and walks, and left unchecked may lead to repeated problems or hearing loss. Understanding why infections start, how to spot them early, and what you can safely do at home until your veterinarian examines your dog will keep your companion more comfortable and reduce the chance of chronic disease.

Why ear infections deserve your attention — what they mean for your dog’s health

Preventing and treating ear infections matters because they are painful and, over time, may damage the ear canal or middle ear in ways that are harder to fix. I typically see dogs that go from a single acute episode to months of recurring trouble when underlying causes aren’t addressed. For breeds with narrow or floppy ear canals, the anatomy itself can trap moisture and debris and make infections more likely.

When infections recur, owners may think intermittent ear cleaning is enough, but recurring episodes often suggest an allergy, skin condition, or structural issue that needs targeted management. Early veterinary care keeps discomfort minimal and reduces the chance of chronic thickening of the canal, scarring, or hearing changes.

For active dogs and known “water dogs,” keeping ears healthy lets them continue swimming and playing without pain. Recognizing when a problem is simple and when it needs professional diagnostics is a practical skill every owner should have.

At a glance: how ear infections form and what’s happening inside

At base, ear infections happen when the normal balance of the ear is upset and naturally present microbes such as bacteria or yeast overgrow. That overgrowth, combined with inflammation, produces pain, discharge, odor, and itching. Multiple factors usually combine rather than a single cause.

Common immediate causes to look for include a recent swim or bath, visible debris inside the outer ear flap, a new ear smell, or sudden scratching and head shaking. Owners often notice pawing at the ear, a dark or creamy discharge, or rubbing the ear on furniture.

Veterinarians confirm a diagnosis by visually examining the ear with an otoscope to see the canal and eardrum when possible, and by taking a small sample of the discharge to examine under a microscope. Cytology—the microscopic evaluation—helps determine whether bacteria, yeast, or mixed organisms are driving the problem and guides treatment choice.

Treatment typically involves cleaning the ear to remove debris and applying topical medications that may include antimicrobial and anti-inflammatory components. If the infection is severe, or if the eardrum is damaged, systemic antibiotics or anti-inflammatories may be prescribed. Addressing any underlying allergy, endocrine disorder, or anatomical issue is often part of preventing recurrence.

Inside your dog’s ear: anatomy and the biology of infection

A dog’s external ear canal is longer and more vertical than a person’s and often forms an L-shaped tube that ends at the eardrum. This shape can limit airflow and make it easier for moisture and debris to linger, which may promote microbial overgrowth in some dogs.

Cerumen, the waxy material produced by the ear lining, is a normal part of ear health. It helps trap dust and microbes and has oils and antimicrobial components. When cerumen production increases or its composition changes—because of inflammation, allergy, or moisture—its normal self-cleaning role may falter and debris can build up.

The skin of the ear supports a community of bacteria and yeasts that usually live in balance. Changes in temperature, humidity, pH, or immune function can allow some organisms to multiply and dominate. For example, Malassezia yeast may become abundant in an environment that is warm and moist, while certain bacteria may flourish when inflammation alters the skin surface.

When microbes overgrow, the ear lining becomes inflamed. The immune system responds with redness, swelling, and increased cerumen, which can narrow the canal and make it harder for topical treatments to reach the affected area. Chronic inflammation may lead to thickening and scarring of the canal over time, which is why early control matters.

Where and when infections strike: environmental triggers and seasonal risks

Moisture is a common trigger. Water from swims or baths can change the ear environment for hours afterward, and if a dog’s ears aren’t dried carefully, bacteria or yeast may be favored. Timing is often notable—owners frequently report a problem appearing within days after a swim or a grooming session.

Breed and ear conformation play a strong role. Dogs with long, drooping ears or narrow ear canals tend to have less air circulation and more trapped debris, which may make infections more likely. I commonly see chronic otitis in spaniels, hounds, and some water breeds.

Allergies—either to food or to environmental allergens—are a frequent underlying factor. Seasonal flare patterns can occur when pollens or molds increase in the environment, and dogs with allergic skin disease commonly develop ear infections at the same time as other skin signs.

Foreign bodies, such as grass awns, and traumatic events—scratching, rough grooming, or insect stings—can injure the canal and allow microbes to invade. Noticing a sudden change in behavior after a walk through tall grass may point toward a foreign body.

Spotting trouble early — warning signs and red flags to watch for

A foul odor coming from the ear, thick pus-like discharge, or bloody secretions suggest a more severe infection that needs prompt veterinary attention. These findings may indicate deeper tissue involvement or secondary complications.

Intense pain, persistent ear rubbing, and violent head shaking are immediate signs that your dog is in distress and should be examined soon. If your dog flinches when the ear is touched or suddenly refuses to have the head handled, that level of pain is a red flag.

Neurologic signs such as a head tilt, circling, loss of balance, or sudden hearing loss suggest the infection may have reached the middle or inner ear and requires urgent veterinary assessment. Recurrent infections that improve briefly with treatment and then return likely point to an underlying cause that needs investigation.

What to do now: practical steps owners can take immediately and at home

Observe and document: note when the problem started, recent activities (swimming, grooming), any medications or topical products used, and whether the other ear shows similar signs. Photographs or short videos of the behavior and the ear’s appearance can be helpful to your veterinarian.

Avoid inserting objects into the ear canal. Cotton swabs or fingers pushed into the ear may push debris deeper, damage the eardrum, or worsen pain. If the outer ear is very dirty, you may gently wipe the visible ear flap with a soft, damp cloth, but do not probe the canal.

Contact your veterinarian for an exam. The vet will likely perform an otoscopic exam and may take samples for cytology and bacterial culture if the infection is severe or recurrent. Be ready to describe your notes and the dog’s history; that information helps direct diagnostics.

Follow prescribed medications exactly. If topical drops are ordered, give them on the schedule recommended and complete the full course unless the vet advises otherwise. Attend any scheduled rechecks; owners sometimes stop treatment when the ear looks better, which can let a smoldering infection persist.

Home fixes and habit changes: environment management plus training tips

Drying ears thoroughly after water exposure reduces moisture-related risks. Gently drying the outer ear with a towel and, for water-prone dogs, using a veterinarian-approved ear-drying spray may help. Avoid forcing air into the canal.

Controlling allergens can reduce frequency in dogs with allergic disease. Work with your veterinarian to identify likely triggers, which may include changing diets for suspected food allergies, using environmental controls during high-pollen seasons, or managing dust and mold in the home.

Grooming should be gentle and regular. Excess hair in the ear canal contributes to humidity and debris retention in some breeds; when hair removal is needed, have it done by a groomer or veterinarian who knows how to do it safely. Overly aggressive plucking or cleaning can cause irritation that invites infection.

Train and desensitize dogs to ear handling by pairing brief, calm handling with high-value treats. Short, frequent sessions that build tolerance make home checks and treatment application far easier and less stressful for both of you.

Helpful tools and products: a gear guide for prevention and basic care

• Vet-recommended ear-cleaning solution formulated for dogs (avoid alcohol-based products unless advised by your vet).
• Soft gauze or cotton balls for wiping the outer ear; do not use cotton swabs that may push material deeper.
• Ear-drying sprays designed for dogs who swim or bathe frequently; choose products your veterinarian endorses.
• Treats and small training rewards to make ear handling a positive experience and to help with regular checks.

When it keeps coming back: causes of recurrent infections and next steps

Recurring infections often mean there is an underlying driver that needs treatment—common examples include allergies, hormonal disorders, or persistent structural issues of the ear canal. Your veterinarian may recommend allergy testing, dietary trials, imaging (such as radiographs or CT) to assess chronic changes, or a referral to a veterinary dermatologist or surgeon when structural correction is needed.

Chronic cases sometimes benefit from longer-term maintenance strategies like periodic topical medications, ear cleanses on a schedule, or environmental changes. Surgery is rarely the first option but may be considered for severe, irreversible canal disease that causes ongoing pain and repeated infections.

Finally, if a dog shows signs of hearing loss or neurologic changes, treat this as an urgent concern. Advanced diagnostics and prompt treatment improve the chances of a good outcome when infection has progressed beyond the external canal.

References and further reading

• Merck Veterinary Manual: Otitis externa in dogs — https://www.merckvetmanual.com/ear-nose-and-throat/otitis/otitis-externa-in-small-animals
• American Veterinary Medical Association (AVMA): Ear infections in dogs — https://www.avma.org/resources/pet-owners/petcare/ear-infections-dogs
• ISCAID/ACVIM consensus statement: Diagnosis and management of canine otitis externa — International Society for Companion Animal Infectious Diseases / American College of Veterinary Internal Medicine (consensus guidance)
• Cornell University College of Veterinary Medicine: Canine ear infections (Otitis) — https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/canine-ear-infections