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Malassezia Dermatitis in Cats

Malassezia pachydermatis is a yeast commonly found on the skin and ears of cats. However, an abnormal overgrowth of the yeast can cause dermatitis, or inflammation of the skin. The exact reasons behind this disease are not yet known, but it has been linked to allergy, seborrhea, and possibly congenital (born with) and hormonal factors.

Malassezia dermatitis is also less common in cats when compared to cats, but can affect any breed of cat.

Symptoms and Types

• Irritation of skin
• Loss of hair (alopecia)
• Greasiness
• Scaly skin
• Redness of affected areas
• Malodorous discharge from lesions
• Patches of skin becoming darker (hyperpigmentation) and epidermal thickening (seen in chronic cases)

Causes

Cats have both a juvenile and adult form of malassezia dermatitis, both of which can be associated with food and/or flea allergies. In rex cats, genetic features such as predisposition to mast cell abnormality and coat and skin types may be a factor in the onset of the disease. Mature cats with the disease, on the other hand, are often associated with thymomas and carcinomas of the pancreas and liver. Other factors that may be a predisposing factor to malessezia dermatitis include concurrent infections and high humidity and temperature.

Diagnosis

You will need to give a thorough history of your cat’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination as well as a biochemistry profile, urinalysis, and complete blood count -- the results of which are typically normal unless the cat has a concurrent disease.

More specific testing includes a culture of the causative organism as well as taking a small skin tissue sample for a skin cytology test. In this test your veterinarian will touch a sterilized cotton swab to the affected area and stain it with Diff-Quik stain on a glass slide. After staining the glass slide is observed under a microscope to demonstrate the yeast in the sample. This will help him or her identify the causative organism.