If Your Dog Keeps Scratching and Smells Bad — Causes and Treatment Timing for Malassezia Dermatitis

Skin & CoatDiseasesMeongsiljang Veterinary Advisory Board

Malassezia dermatitis is a condition in which the yeast that naturally lives on a dog’s skin overgrows, causing itching, a foul odor, and changes in skin color. To prevent recurrence, antifungal treatment must be combined with addressing underlying causes such as allergies or endocrine disorders.

What Is Malassezia Dermatitis in Dogs?

The puppy's belly and groin skin, reddened by Malassezia dermatitis

Malassezia dermatitis is a skin condition in dogs caused by the overgrowth of Malassezia pachydermatis, a yeast that normally resides on canine skin. This overgrowth leads to skin inflammation and severe itching. The most critical aspect of treatment is addressing the underlying cause of the overgrowth, not just the yeast itself. If underlying conditions such as allergies, atopy, or endocrine disorders are not resolved, the condition is likely to recur even after treatment.

Why Does Malassezia Yeast Overgrow?

Malassezia is a normal commensal yeast that can be cultured from the skin of healthy dogs. However, in most cases, secondary overgrowth triggered by an underlying condition leads to dermatitis.

Allergies and Atopy: This is the most common and significant cause. Dogs with atopic dermatitis have a compromised skin barrier and may exhibit hypersensitivity to even small numbers of yeast, resulting in severe itching.

Endocrine Disorders (such as Hypothyroidism and Cushing’s Syndrome): When these hormonal conditions are present, secondary Malassezia overgrowth can occur. Underlying diseases are confirmed through blood, biochemistry, and endocrine testing.

Skin Folds and Chronic Moisture: Overgrowth tends to concentrate in moist, poorly ventilated intertriginous areas, such as the inner ear, facial and lip folds, between the toes, and the armpits.

Key Point: Studies indicate that medications like steroids or cyclosporine do not inherently increase the total count of Malassezia in dogs. Therefore, the cornerstone of managing overgrowth is not just medication, but concurrently addressing underlying conditions such as allergies and endocrine disorders.

Suspect Malassezia Dermatitis If You See These Symptoms

Itching (Pruritus): Your pet licks or scratches their paws, ears, groin, and armpits excessively. Oily, sticky skin: The skin appears shiny, and oil transfers to your hands when touched. Distinctive odor: If a musty or yeast-like smell persists even after bathing, suspect an underlying issue. Redness (Erythema): The skin becomes red and feels warm to the touch. Hyperpigmentation and thickened skin: Repeated irritation causes the skin to darken and thicken. Concurrent ear inflammation: Dark discharge appears in the ears, accompanied by frequent head shaking or scratching.

A Cocker Spaniel with thickened, hyperpigmented skin due to chronic Malassezia dermatitis

Seek Immediate Veterinary Care for These Symptoms

Seek immediate veterinary care if your pet’s skin becomes suddenly red or swollen all over, if scratching has caused bleeding wounds, if they refuse to eat or appear lethargic for more than 24 hours, or if skin lesions spread rapidly over a short period. These situations can lead to secondary bacterial infections.

How Is It Diagnosed at the Veterinary Clinic?

After reviewing the clinical signs, your veterinarian will proceed with the following diagnostic methods:

Tape impression cytology: A piece of clear tape is pressed onto the skin and then examined under a microscope to count the number of yeast cells. This is the quickest and simplest initial test.

Ear swab test: Ear discharge is collected with a cotton swab and examined under a microscope.

Skin biopsy: If the condition is chronic or unresponsive to treatment, a tissue sample is taken for detailed analysis.

Tests for underlying conditions: Thyroid and adrenal function tests, allergy testing, and other relevant exams are performed to identify the root cause.

How Is Treatment Carried Out?

Topical treatment (first-line): Regularly use antifungal shampoo (containing chlorhexidine and climbazole), antifungal wipes, and ear cleaners. According to veterinary dermatology textbooks, topical therapy is the first-line choice.

Systemic antifungals: Oral medication is added when symptoms are severe or when topical treatment alone is insufficient. The veterinarian determines the dosage and duration based on the pet’s weight and symptoms.

Treatment of underlying conditions: If underlying causes such as allergies or thyroid disorders are not treated concurrently, the condition is likely to recur.

A veterinarian treating a dog’s skin condition with antifungal shampoo

Home Care Points You Can Do

Follow the shampoo contact time: Prescription shampoos need to sit on the skin for 5–10 minutes before rinsing to be effective. Use them once or twice a week, adjusting frequency as directed by your veterinarian.

Regular ear cleaning: Wipe away moisture from inside the ears, and before bathing, place cotton in the ear canal to prevent water from entering.

Keep skin folds dry: For breeds with wrinkles, such as Bulldogs and Pugs, clean and thoroughly dry the folds every day.

Dietary management: If food allergies are the cause, consult your veterinarian about switching to a hydrolyzed diet.

Keep regular follow-up appointments: Attend scheduled check-ups to monitor treatment progress and manage any underlying conditions.

A pet owner cleaning a bulldog’s skin folds at home

These Breeds Require Special Attention

Basset Hounds, Cocker Spaniels, West Highland White Terriers, Shih Tzus, and Bulldogs are reported in veterinary dermatology textbooks as breeds prone to Malassezia dermatitis and atopic dermatitis. In particular, even healthy Basset Hounds tend to have higher baseline levels of Malassezia on their skin and mucous membranes. Breeds with deep facial folds, such as Pugs, require special attention, as yeast can easily proliferate in intertriginous areas like the inside of skin folds. If you own one of these breeds, it is advisable to regularly check your pet’s skin and ears even in the absence of symptoms, and to establish a routine of antifungal care (such as medicated baths and cleansing) as directed by your veterinarian.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can Malassezia dermatitis be transmitted to humans?

Malassezia pachydermatis does not survive well on human skin, so it is rarely transmitted to healthy pet owners. However, individuals with severely compromised immune systems, such as those undergoing cancer treatment or newborns, should minimize contact with their pets and practice thorough hand hygiene.

What causes the condition to recur after treatment?

The most common reason is that underlying conditions, such as allergies or thyroid disorders, are not being treated concurrently. While antifungal therapy alone can reduce the fungal load, the environment that promotes overgrowth remains unchanged, leading to recurrence shortly after. To prevent relapse, it is essential to manage the underlying condition alongside regular medicated baths.

How often should I use antifungal shampoo?

During the acute phase, bathing two to three times a week is typical, while once a week is generally sufficient during the maintenance phase once symptoms have improved. The exact frequency should follow your veterinarian’s prescription, as overly frequent bathing can actually damage the skin barrier.

Can Malassezia also occur in the ears?

Yes, Malassezia ear infections (otitis externa) are very common. If you notice black or brown discharge from the ears, a yeast-like odor, or persistent scratching, you should suspect otitis externa. It often occurs concurrently with Malassezia dermatitis.

Can Malassezia dermatitis be completely cured?

When the underlying condition is well managed, symptoms can be suppressed in the long term. However, if the cause is a chronic disease such as allergies, the realistic goal is not a cure, but rather effective management to prevent recurrence. Consistent regular check-ups and preventive care are key.

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References

[1] BSAVA Manual of Canine and Feline Dermatology, 4th Ed. British Small Animal Veterinary Association, 2019. Chapter: Malassezia dermatitis.

[2] Cafarchia C, Gasser HB, Latrofa MS et al. Genetic variants of Malassezia pachydermatis from canine skin: body distribution and phospholipase activity. FEMS Yeast Research 8, 451–459, 2008.

[3] Cavana P, Peano A, Petit JY et al. A pilot study of the efficacy of wipes containing chlorhexidine 0.3%, climbazole 0.5% and Tris-EDTA to reduce Malassezia pachydermatis populations on canine skin. Veterinary Dermatology 26, 276–283, 2015.

[4] Kano FR, Aramaki C, Murayama WN et al. High multi-azole-resistant Malassezia pachydermatis clinical isolates from canine Malassezia dermatitis. Medical Mycology 58, 191–200, 2019.

[5] Nuttall T, Harvey RG, McKeever PJ. A Colour Handbook of Skin Diseases of the Dog and Cat, 2nd Ed. CRC Press, 2009.