A yeast infection in a dog's ear is an overgrowth of Malassezia pachydermatis, a yeast that normally lives in small numbers on dogs' skin and in their ears.1,2 When something changes the ear's environment, most often an allergy, the yeast multiplies and causes itching, odor and a brown, waxy discharge.1,3 Yeast is the most common secondary organism in dog ear infections.4 This page explains the signs, causes, how vets confirm it, treatment and how to stop it coming back.
See a vet promptly if your dog:
What the Research Shows
- Yeast is the top secondary invader. Malassezia was found in 66 of 100 dogs with ear infections, more often than cocci (38) or rod bacteria (22).4
- It lives in healthy ears too. Malassezia was cultured from 76.5% of infected ears but also from 37.5% of healthy ears.2
- The microscope test is reliable. Ear cytology detected Malassezia with 90.2% sensitivity and 100% specificity compared with culture.10
- Floppy ears may be more prone. In one study, 51.4% of dogs with pendulous ears tested positive, compared with 34.8% of dogs with upright ears, although the difference wasn't statistically significant.10
- Stubborn cases can be turned around. In 59 dogs whose yeast otitis hadn't responded to treatment, 91% of affected ears improved after a thorough ear flush and a full management plan.9
What Is a Yeast Ear Infection?
Malassezia overgrowth happens when the ear becomes warm, moist, greasy or inflamed. It isn't considered contagious; it's an overgrowth of yeast your dog already carries.1,2 Because healthy ears can carry some yeast, vets diagnose a yeast infection based on signs and the number of yeast seen under the microscope, and sometimes on response to treatment.1,3
Signs of a Yeast Infection in a Dog's Ear
- Brown, waxy or greasy discharge11,3,12
- An unpleasant smell
- Redness and itching; head shaking and scratching3,12
- Thickened, darkened skin in long-standing cases12
Yeast and bacterial infections often occur together, so the color of the discharge alone can't tell you what's going on.4,5
What Causes Yeast Ear Infections?
- Allergies: Malassezia overgrowth and atopic dermatitis commonly go together.1 See allergies in dogs.
- Other skin and hormone conditions, such as skin scaling disorders and hormone diseases.1,5 See thyroid disease in dogs.
- Moisture and ear shape, including swimming and floppy ears.5,10
- Breed: West Highland White Terriers, Basset Hounds, Shih Tzus, English Setters and Cocker Spaniels are among the breeds prone to Malassezia problems.1,10
Many dogs with yeast ear infections also have yeasty skin elsewhere, such as the paws or armpits. See yeast infections on dogs' skin.
How Vets Diagnose a Yeast Ear Infection
Your vet will examine the ear canal and eardrum with an otoscope and take a swab for cytology. The yeast look like small oval, budding cells (often described as peanut-shaped) under the microscope.1,12 Specialists commonly treat an average of 5 or more yeast per high-power field as abnormal, though there's no universal cutoff.6,1 Cytology also shows whether bacteria are present, which changes the treatment.5 Routine culture adds little for yeast; cytology is the main test.1,12
Treatment
- Ear cleaning to remove wax and discharge so medication can reach the skin.6,13
- Medicated ear drops containing an antifungal, usually combined with a steroid to reduce swelling and itch, and often an antibiotic.5,12
- Long-acting clinic treatments (one or two doses), which include an antifungal and are approved for ear infections involving Malassezia.14,15
- Oral antifungals are sometimes added for severe or widespread skin yeast, but there's little evidence they work for ear yeast on their own; ear drops remain the main treatment.1,12
Most acute infections improve within 2 to 4 weeks. Your vet will recheck with a swab to make sure the yeast has cleared.5 See treating dog ear infections.
Preventing Yeast Ear Infections
- Control allergies, the most common underlying cause.1,9
- Keep ears dry after swimming or baths.8
- Use a cleaner your vet recommends, at the frequency they suggest; overcleaning can irritate.16,6
- Ask about maintenance therapy: for allergic dogs, twice-weekly use of a mild steroid ear product shows promise for preventing yeast flare-ups.1
Frequently Asked Questions
What does a yeast infection in a dog's ear look like?
Brown, waxy or greasy discharge with redness and a musty smell.
What causes yeast in dogs' ears?
An overgrowth of yeast that normally lives on the skin, most often triggered by allergies, moisture or floppy ears.
Is a dog ear yeast infection contagious?
No. It's an overgrowth of your dog's own yeast, not an infection caught from another animal.
Can I treat a dog ear yeast infection at home?
See a vet first. A swab shows whether bacteria are also involved, and an eardrum may be damaged, which affects which drops are safe.
How long does a dog ear yeast infection take to clear?
Usually 2 to 4 weeks with treatment. Chronic cases take longer.
Does diet cause yeast ear infections?
Food allergies can be an underlying cause in some dogs. No studies show that cutting sugar or carbs prevents ear yeast; Malassezia feeds mainly on skin oils.
Why does my dog keep getting yeast ear infections?
Usually because an underlying cause, most often allergies, isn't controlled.
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Sources and further reading
This article was rewritten and fact-checked on October 15, 2026 against current veterinary references and specialist guidelines:
- Bond R, Morris DO, Guillot J, et al. Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology. Veterinary Dermatology, 2020.
- Nobre MO, Castro AP, Nascente PS, Ferreiro L, Meireles MCA. Occurrence of Malassezia pachydermatis and other infectious agents as cause of external otitis in dogs from Rio Grande do Sul State, Brazil. Brazilian Journal of Microbiology, 2001.
- Cabañes FJ. Diagnosis of Malassezia dermatitis and otitis in dogs and cats: is it just a matter of counting? Revista Iberoamericana de Micología, 2021.
- Saridomichelakis MN, Farmaki R, Leontides LS, Koutinas AF. Aetiology of canine otitis externa: a retrospective study of 100 cases. Veterinary Dermatology, 2007.
- Hoff S. Otitis externa in animals. Merck Veterinary Manual, April 2026.
- Koch S. The challenge of chronic otitis in dogs: diagnosis and treatment. Today's Veterinary Practice, 2017, updated 2022.
- Otitis media. LAVC Annual Conference, 2009. Conference proceedings hosted by IVIS.
- Cornell Richard P. Riney Canine Health Center. Itchy ear problems.
- Nuttall T. Managing recurrent otitis externa in dogs: what have we learned and what can we do better? Journal of the American Veterinary Medical Association, 2023.
- Čonková E, Sesztáková E, Páleník Ľ, Smrčo P, Bílek J. Prevalence of Malassezia pachydermatis in dogs with suspected Malassezia dermatitis or otitis in Slovakia. Acta Veterinaria Brno, 2011.
- Merck Veterinary Manual. Malassezia (yeast) otitis, dog (image, courtesy of Dr. Stephen White).
- Doerr K. Malassezia dermatitis and otitis in dogs. Veterinary Focus, 2015. Hosted by IVIS (full text for veterinary professionals).
- Fontaine J. How do I manage otitis? EVC Voorjaarsdagen, 2008. Conference proceedings hosted by IVIS.
- U.S. Food and Drug Administration. Freedom of Information summary: Claro (florfenicol, terbinafine, mometasone furoate) otic solution, NADA 141-440. 2015.
- U.S. Food and Drug Administration. Freedom of Information summary: Osurnia (florfenicol, terbinafine, betamethasone acetate) otic gel, NADA 141-437. 2014.
- Weir M, Panning A. Instructions for ear cleaning in dogs. VCA Animal Hospitals, August 2025.
About this article
Last updated : fully rewritten using published studies, the World Association for Veterinary Dermatology Malassezia guidelines, the Merck Veterinary Manual, specialist dermatology articles and IVIS-hosted material; added the research summary, signs, causes, diagnosis, treatment, prevention, key takeaways and FAQ.
This page is for general information and is not a substitute for an exam by your veterinarian.
