Ear Infections in Dogs: Causes, Symptoms, and Classification

What does an ear infection in dogs mean?

An ear infection in dogs is an inflammatory condition of the ear canal, typically referred to in veterinary medicine as otitis externa (outer ear), otitis media (middle ear), or otitis interna (inner ear). The most common form is otitis externa: It affects the visible portion of the ear extending outward from the eardrum and, according to epidemiological studies, ranks among the five most common reasons for visits to small animal clinics.

Common symptoms include head shaking, scratching the ear, a foul odor, redness, discharge, or tilting the head to one side. An ear infection is rarely a standalone condition but is almost always a symptom of an underlying cause—and that is the key to understanding it.

Background and Academic Context

In 2007, Saridomichelakis et al. published a widely cited review on the etiology of otitis externa and established a classification system—still in use today—that identifies predisposing, primary, secondary, and perpetuating factors. Primary causes are direct triggers such as allergies, parasites, or foreign bodies. Secondary factors—mostly bacteria (Staphylococcus, Pseudomonas) or yeasts (Malassezia pachydermatis)—colonize tissue that is already irritated.

According to current research, allergies are the most common primary cause: atopic dermatitis and food-related reactions account for a significant proportion of chronic otitis (Bajwa 2019). Anatomical predispositions also play a role—floppy ears with limited ventilation, narrow ear canals in some breeds, or excessive hair growth in the canal.

Important to note: Untreated otitis externa can become chronic, damage the eardrum, and spread to the middle or inner ear. This can lead to balance disorders, hearing loss, or neurological deficits.

Vitomalia-Position

If you suspect an ear infection, we strongly recommend taking your pet to the veterinarian—no home remedies, no homemade cleaning solutions, and no waiting to see if it gets better on its own. Otitis is a medical condition that must be diagnosed through otoscopic examination and cytology. This is not an exaggeration; it simply reflects current veterinary medical standards.

We strongly advise against cleaning ears with cotton swabs, alcohol, vinegar water, or other "DIY rinses." These methods can damage the mucous membrane, push secretions deeper into the ear canal, or worsen an existing ear infection. Note: The information in this article is not a substitute for a veterinary diagnosis or treatment.

When is an ear infection in dogs a cause for concern?

Specific everyday situations in which this issue becomes pressing:

• Sudden, persistent head shaking or ear scratching —usually one of the first warning signs
• A noticeable odor coming from the ear, often sweet and rancid (indicating yeast) or pus-like (indicating bacteria)
• Tilting the head to one side or being sensitive to touch when stroked
• Dogs with a known allergy or atopic dermatitis – chronically increased risk
• After swimming or bathing – moisture in the ear canal as a contributing factor

The extent of the inflammation cannot be reliably assessed by visual inspection—the eardrum and the deep canal cannot be evaluated without an otoscope.

Practical application

1. Take symptoms seriously: If your pet is shaking its head, scratching, or has an unusual odor or discharge, have a veterinarian examine it promptly.
2. Keep your own examination to a minimum: Carefully examine the pavilion; do not probe into the canal.
3. Preparing for a vet appointment: Notes on when symptoms began, bathing habits, changes in diet, and known allergies.
4. Follow the prescribed treatment consistently: use drops, rinses, or systemic medication exactly as directed—stopping treatment increases the risk of recurrence.
5. Help identify the cause: In cases of recurrent otitis, a process of elimination is advisable (see elimination diet).
6. Establish a routine check: For high-risk dogs, perform regular visual inspections and, if necessary, use a cleaning solution recommended by a veterinarian.

Common Mistakes and Myths

• "A little wax in the ear is normal." That's partly true—but changes in the odor, color, or amount of earwax are no small matter.
• "Olive oil or tea tree oil helps." Wrong. Tea tree oil can be toxic, and oils form a film under which pathogens can multiply.
• "If the dog stops scratching, it's gone." The absence of symptoms does not mean a cure. Bacteria and yeast can still persist—complete the course of treatment.
• "Dogs with floppy ears automatically get otitis." Increased risk, yes; automatic, no. Management and allergy status are more decisive factors than anatomy alone.

State of the art in 2026

Veterinary dermatology has made significant progress over the past decade. Recent consensus papers (Bajwa 2019, Paterson 2018) emphasize structured diagnostics with cytology as the standard approach and the identification of multifactorial causes. Antibiotic resistance, particularly in Pseudomonas aeruginosa, is a growing problem and requires targeted therapy based on antibiotic susceptibility testing. What is well established: Allergies are the leading primary cause of chronic otitis. What remains unclear: The optimal cleaning intervals and products for at-risk dogs in daily practice are not supported by large randomized studies.

Frequently Asked Questions

How can I spot an ear infection in my dog early on?

Frequent head shaking, scratching the ear, an unusual odor, or brownish to purulent discharge are early signs. Sensitivity to touch on the head is also a symptom.

Should I clean my ears regularly?

For healthy dogs with no underlying health issues, cleaning is usually not necessary. For at-risk dogs, use only products recommended by a veterinarian and follow the recommended schedule.

Can an ear infection go away on its own?

Rare and unpredictable. Spontaneous improvement is possible, but there is a real risk of the condition becoming chronic and causing damage to the eardrum.

Are certain breeds more commonly affected?

Cocker spaniels, Labradors, poodles, and bulldogs are mentioned more frequently in studies—but allergies and lifestyle are often more decisive factors than breed.

Related terms

• Allergies in Dogs
• Atopic dermatitis
• Elimination diet
• Parasites in Dogs
• Itching in Dogs
• Food allergy
• Ear mites in dogs

Sources and further reading

1. Saridomichelakis, M. N., Farmaki, R., Leontides, L. S., & Koutinas, A. F. (2007). Aetiology of canine otitis externa: a retrospective study of 100 cases. Veterinary Dermatology, 18(5), 341-347.
2. Bajwa, J. (2019). Canine otitis externa - Treatment and complications. Canadian Veterinary Journal, 60(1), 97-99.
3. Paterson, S. (2018). Discovering the causes of otitis externa. In Practice, 38(Suppl 2), 7-11.
4. Zur, G., Lifshitz, B., & Bdolah-Abram, T. (2011). The association between the signalment, common causes of canine otitis externa and pathogens. Journal of Small Animal Practice, 52(5), 254-258.
5. Nuttall, T. (2016). Successful management of otitis externa. In Practice, 38(Suppl 2), 17-21.