What is Malassezia in dogs?

Malassezia pachydermatis is a yeast (fungus) that normally lives on dog skin and in the ears. When the skin's defences are impaired (by allergies, moisture, inflammation), it multiplies excessively, causing dermatitis and otitis with intense itching and a characteristic rancid odour.

What are the symptoms of Malassezia?

Intense itching, rancid or "corn chip" smell, thickened and darkened skin (lichenification), redness, crusts and greasy skin. Most affected areas: ears, paws (between toes), groin, armpits, skin folds and around the mouth.

How is Malassezia diagnosed?

The vet takes a sample from the skin (acetate tape or swab) and examines it under the microscope. Malassezia yeasts have a characteristic "peanut" or "snowman" shape. Diagnosis can be confirmed in minutes.

How is Malassezia treated in dogs?

With topical antifungals (shampoo with ketoconazole, miconazole or chlorhexidine) 2-3 times per week for 3-6 weeks. In severe or generalised cases, oral ketoconazole or itraconazole. Always treat the underlying cause (allergy, skin folds, moisture).

Malassezia in Dogs: Yeast Dermatitis, Itching and Treatment

What Is Malassezia Dermatitis?

Malassezia pachydermatis is a commensal yeast — it normally lives on dog skin and in the ears without causing harm. When the skin barrier is disrupted (by allergies, chronic moisture, inflammation, hypothyroidism or skin folds), the yeast multiplies and causes infection. It is one of the most common causes of itching and odour in dogs, often as a complication of environmental or food allergy.

Symptoms and Distribution

Odour: rancid, "corn chips" or yeasty — the most characteristic symptom.
Intense itching: the dog scratches, licks and bites non-stop.
Thickened, darkened skin (lichenification, hyperpigmentation).
Redness (erythema), crusts and greasy sebaceous skin.
Favourite sites: ears (dark brown discharge with strong odour), paws (between toes — the famous "Fritos feet"), groin, armpits, neck folds and lip margins.

Most Affected Breeds

West Highland White Terrier, Basset Hound, Cocker Spaniel, Shar Pei, English and French Bulldog, Boxer, Poodle, Dachshund and any breed with abundant skin folds or allergic predisposition.

Diagnosis

Acetate tape pressed onto skin, stained with Diff-Quik: yeasts show a characteristic "peanut" or "biphasic snowman" shape.
Ear swab + staining for Malassezia otitis.
Culture: rarely needed (Malassezia does not grow on standard agar).

Treatment

Topical (first line):

Antifungal shampoo with ketoconazole 2 % or miconazole + chlorhexidine: leave on 5-10 minutes before rinsing. 2-3 baths per week for 3-6 weeks.
Chlorhexidine + miconazole sprays or mousse for localised areas.
Ear cleaning with antifungal otic solution.

Oral (generalised cases or no topical response):

Ketoconazole 5-10 mg/kg/day or itraconazole 5 mg/kg/day, 3-6 weeks.

Always treat the underlying cause: without addressing the allergy, skin folds or moisture, Malassezia will recur. Oclacitinib (Apoquel), cytopenia (Cytopoint) or allergen immunotherapy may be needed if allergy is the precipitating factor.