Ear infections are among the most common reasons dogs visit the veterinarian, affecting an estimated 10-20% of the canine population. The medical term for an outer ear infection is otitis externa — inflammation and infection of the external ear canal. Dogs are more susceptible to ear infections than humans due to the shape of their ear canals, which form an “L” shape that can trap moisture, debris, and microorganisms. While ear infections are usually not emergencies, they cause significant discomfort and can lead to serious complications if left untreated or if they become chronic. Your veterinarian can identify the type of infection and prescribe appropriate treatment.
Overview
The canine ear canal is a warm, dark, moist environment — ideal conditions for the growth of bacteria and yeast. Ear infections in dogs are classified by location:
- Otitis externa — Infection of the outer ear canal (the most common type and the focus of this guide).
- Otitis media — Infection of the middle ear, often resulting from chronic or severe otitis externa that has progressed through the tympanic membrane (eardrum).
- Otitis interna — Infection of the inner ear, which can affect balance and hearing.
Common Causes and Contributing Factors
Ear infections are usually secondary to an underlying cause. Understanding and addressing the root cause is essential for preventing recurrence:
- Allergies — Atopic dermatitis and food allergies are the most common underlying cause of recurrent ear infections in dogs. Allergic inflammation changes the ear canal environment, promoting microbial overgrowth.
- Moisture — Swimming, bathing, or humid environments can create conditions favorable for infection.
- Ear anatomy — Breeds with floppy ears (Cocker Spaniels, Basset Hounds, Labrador Retrievers), narrow ear canals (Shar-Peis), or excessive hair in the ear canal (Poodles, Schnauzers) are predisposed.
- Foreign bodies — Grass awns, plant material, or debris lodged in the ear canal.
- Ear mites — More common in puppies and outdoor dogs; less common in adult dogs than in cats.
- Endocrine disorders — Hypothyroidism and Cushing’s disease can predispose dogs to ear infections.
- Autoimmune conditions — Can affect the ear canal lining.
Types of Infection
- Yeast infections (Malassezia) — Often produce a dark brown, waxy discharge with a characteristic sweet or musty odor.
- Bacterial infections — Can produce yellow, green, or bloody discharge. Common bacteria include Staphylococcus, Streptococcus, Pseudomonas, and Proteus species.
- Mixed infections — Many ear infections involve both bacteria and yeast simultaneously.
Symptoms
Signs that your dog may have an ear infection include:
- Head shaking or head tilting
- Scratching or pawing at the affected ear
- Redness and swelling of the ear flap or canal opening
- Discharge (brown, yellow, green, or bloody depending on the type of infection)
- Odor from the ear
- Pain when the ear is touched (your dog may pull away, whimper, or become irritable)
- Crusting or scabbing around the ear opening
- Hearing loss (if the infection has affected deeper structures)
- Loss of balance or walking in circles (if middle or inner ear is involved — seek veterinary attention promptly)
If your dog shows signs of head tilt, circling, loss of balance, facial nerve paralysis, or severe pain, seek veterinary attention promptly, as these may indicate middle or inner ear involvement.
Diagnosis
Proper diagnosis is important because the treatment differs based on the type of organism causing the infection:
- Otoscopic examination — Your veterinarian will use an otoscope to visualize the ear canal and eardrum. This helps assess the severity of inflammation, identify foreign bodies, and determine whether the eardrum is intact.
- Cytology (ear swab) — A sample of ear discharge is examined under a microscope to identify whether bacteria, yeast, or both are present, and in what quantity. This is the most important diagnostic step for guiding treatment.
- Culture and sensitivity — For chronic, recurrent, or severe infections (especially those involving Pseudomonas or other resistant bacteria), your veterinarian may submit a sample for bacterial culture to identify the specific organism and determine which antibiotics it is susceptible to.
- Assessment for underlying causes — If ear infections are recurrent, your veterinarian will investigate potential underlying causes such as allergies, endocrine disease, or anatomical factors.
Treatment Options
Treatment depends on the type and severity of infection, whether the eardrum is intact, and whether there is an underlying cause that must be addressed.
Medication Overview
| Medication | Type | Use | Key Considerations |
|---|---|---|---|
| Otibiotic combination drops (Osurnia, Mometamax, Posatex) | Topical ear medication | Contain a combination of antibiotic + antifungal + corticosteroid in a single product | The mainstay of treatment for uncomplicated otitis externa. Osurnia is applied by the veterinarian (two doses, 1 week apart) and does not require daily home application. Mometamax and Posatex are typically applied daily at home. |
| TrizEDTA ear cleaner | Ear flush/cleaner | Chelating agent that disrupts bacterial biofilm and enhances antibiotic penetration | Often used before applying topical medications. TrizEDTA can improve the effectiveness of subsequent antibiotic drops, particularly against Pseudomonas. |
| Chlorhexidine-based ear cleaners | Antimicrobial ear cleaner | General cleaning and mild antimicrobial activity | Used for routine maintenance cleaning and mild infections. Should not be used if the eardrum is ruptured. |
| Ketoconazole or fluconazole | Oral antifungal | Treats severe or deep yeast infections that do not respond to topical therapy alone | Reserved for cases where topical antifungal treatment is insufficient. Requires liver function monitoring with prolonged use. |
| Oral antibiotics (cephalexin, enrofloxacin, fluoroquinolones) | Systemic antibiotics | For severe otitis externa, otitis media, or infections that have spread beyond the ear canal | Oral antibiotics are not needed for most uncomplicated ear infections. They are reserved for severe cases, middle ear involvement, or when topical treatment alone is not effective. |
| Oral corticosteroids (prednisone) | Anti-inflammatory | Reduces severe ear canal swelling to allow topical medications to penetrate | Short courses may be prescribed when the ear canal is so swollen that topical drops cannot reach the infection. |
Treatment Protocol
A typical treatment protocol for an uncomplicated ear infection includes:
- Veterinary ear cleaning — Your veterinarian may perform a thorough ear flush under sedation if the ears are severely affected or painful.
- Topical medication — Applied directly into the ear canal as prescribed (typically once or twice daily for 7-14 days, depending on the product and severity).
- Ear cleaning at home — Your veterinarian may recommend regular cleaning with an appropriate ear cleaner before applying medication. Follow their specific instructions regarding timing and technique.
- Recheck examination — A follow-up visit (usually 2-3 weeks after starting treatment) is important to confirm the infection has resolved. Stopping treatment early because the ear “looks better” is a common cause of recurrence and antibiotic resistance.
- Address underlying causes — If allergies are suspected as the underlying trigger, your veterinarian will discuss a long-term management plan.
Ear Cleaning Technique
If your veterinarian recommends home ear cleaning:
- Fill the ear canal with the prescribed cleaner until you can see liquid at the opening.
- Gently massage the base of the ear for 20-30 seconds (you should hear a squishing sound).
- Allow your dog to shake their head.
- Wipe away visible debris and excess cleaner with a cotton ball or gauze. Never insert cotton swabs (Q-tips) into the ear canal.
- Apply medication as directed after the ear has dried, if instructed.
Monitoring
- Complete the full course of treatment as prescribed, even if symptoms improve before the medication runs out.
- Recheck appointment — Essential to confirm the infection has fully resolved through repeat otoscopy and cytology.
- Watch for recurrence — If ear infections return within weeks to months, a thorough investigation into underlying causes (particularly allergies) is warranted.
- Monitor for complications — Signs of worsening (head tilt, balance issues, increasing pain, bloody discharge) should prompt an immediate veterinary visit.
Prognosis
- Uncomplicated otitis externa — Most cases resolve with appropriate treatment within 2-4 weeks.
- Chronic or recurrent infections — Prognosis depends on identifying and managing the underlying cause. Dogs with allergic ear disease may need lifelong ear maintenance, allergy management, or both.
- Otitis media — Requires more aggressive and prolonged treatment but can often be resolved or managed.
- End-stage ears — Chronic, untreated ear infections can lead to permanent ear canal changes (stenosis, calcification) that may ultimately require surgery (total ear canal ablation and bulla osteotomy, or TECA-BO) for resolution.
Early treatment and follow-through with recheck examinations give the best outcomes.
Frequently Asked Questions
Can I use hydrogen peroxide to clean my dog’s ears? Hydrogen peroxide is not recommended for ear cleaning in dogs. It can be irritating to inflamed tissue and may not be effective against the organisms causing the infection. Use only veterinarian-recommended ear cleaning solutions.
Are ear infections contagious to other dogs or to humans? Most ear infections in dogs are caused by overgrowth of organisms (yeast and bacteria) that are normal residents of the ear in small numbers. They are not typically contagious. The exception is ear mite infections, which can spread between animals.
Why does my dog keep getting ear infections? Recurrent ear infections almost always indicate an underlying problem, most commonly allergies (environmental or food). Other possibilities include endocrine disorders, anatomical factors, or moisture exposure. If your dog has more than 2-3 ear infections per year, discuss a thorough workup with your veterinarian.
Can I use over-the-counter ear drops for my dog? Over-the-counter ear cleaners may be appropriate for routine maintenance in healthy ears, but they are not a substitute for prescription treatment of an active infection. Using the wrong product can delay proper treatment, worsen the infection, or cause harm if the eardrum is compromised.
How can I prevent ear infections? Regular ear cleaning (especially after swimming or bathing), keeping ears dry, managing underlying allergies, and maintaining routine veterinary check-ups can all help reduce the risk of ear infections. Your veterinarian can recommend an appropriate cleaning schedule and product for your dog.
Sources
- Rosser EJ Jr. “Causes of otitis externa.” Veterinary Clinics of North America: Small Animal Practice. 2004;34(2):459-468.
- Paterson S. “Topical ear treatment — options, indications and limitations of current therapy.” Journal of Small Animal Practice. 2016;57(12):668-678.
- Nuttall T, Bensignor E. “A pilot study to develop an analogue scale for assessing the severity of otitis externa in the dog.” Veterinary Dermatology. 2014;25(6):486-e82.
- Saridomichelakis MN, Farmaki R, Leontides LS, Koutinas AF. “Aetiology of canine otitis externa: a retrospective study of 100 cases.” Veterinary Dermatology. 2007;18(5):341-347.
- Cole LK. “Otoscopic evaluation of the ear canal.” Veterinary Clinics of North America: Small Animal Practice. 2004;34(2):397-410.
- Merck Veterinary Manual. “Otitis Externa in Dogs and Cats.” merckvetmanual.com