Malassezia

If your dog has greasy, thickened skin or recurrent ear problems they may be suffering from Malassezia. This fungal/yeast infection of the skin can be mild or extensive and may indicate that there is an underlying health problem. If your dog has any skin lesions you should make an appointment to see your veterinarian – it may be that the skin disease is an indication that something more serious is going on.

Malassezia yeasts are often found on the skin of normal animals where they cause no problems. Skin disease develops in animals that have a reduced immune response, damaged skin or an underlying allergy. Once the skin resistance is reduced the yeast can multiply and spread. Some breeds of dog, eg Bassets, Westies and Cocker spaniels appear to be particularly prone to developing problems associated with Malassezia. The disease is more common in warm, humid climates and warmer more humid times of the year.

It has probably always carried a few Malassezia yeasts, however there are some underlying conditions that can weaken your dog’s immune system and make them more likely to get Malassezia infections. These include severe illnesses like diabetes and thyroid problems, cancer and long-term problems like allergies. However, simple changes to the skin (such as constant wetting due to excessive drooling), can result in local infections. Treatment with steroids or antibiotics for other problems can affect the environment on the skin and predispose to an overgrowth of Malassezia.

Dogs with Malassezia infections are very itchy and they tend to smell a bit ‘yeasty’. If they have Malassezia ear infections, they will constantly shake their head and scratch at their ears. A thick black waxy material may be seen crusting around the ears and the opening of the ear canal. Acne and chin swelling may be noticed but skin changes can occur at any site. Wherever disease is present the affected area will be itchy so that your dog will want to lick or scratch at the site. Some dogs develop disease on their feet and may lick and bite at their paws.

Your veterinarian may suspect that your dog has a Malassezia infection just by looking at the skin. A sample of the skin surface can be simply collected using a piece of clear tape stuck to the skin and pulled off. This can be looked at under a microscope to identify the yeast. Sometimes Malassezia can be more difficult to find and a culture or skin biopsy may be advised to look for underlying problems. Culture is performed by rubbing a swab over the affected skin and sending it to a specialist laboratory. The results can take a week or so. Skin biopsy is a minor surgical procedure, removing a full-thickness piece of skin (or several pieces) and submission to a specialist laboratory. Results will take several days. However, even once a diagnosis of Malassezia has been confirmed your veterinarian may want to do some additional tests to see if they can find an underlying cause. These may include blood tests and urine samples for laboratory analysis.

Your veterinarian will want to rule out parasitic conditions such as Demodex or Sarcoptes (mange mites) and flea infections; ringworm (a fungal infection) or acne as these can appear similar to, or occur at the same time as, Malassezia. Another common cause of ear problems, as described above, is ear mites (Otodectes). These are usually easily diagnosed by your veterinarian examining ear wax material under the microscope. Other more generalized problems such as some hormonal disorders can have the appearance of Malassezia, or, in some cases, may result in Malassezia infections.

In mild cases no treatment may be needed although your veterinarian may give you a wash to occasionally clean the skin surface in affected areas. Ear drops can be used to control infection in the ears. For more severe skin lesions special shampoos or skin creams can be prescribed. Treatment with tablets is only used in severe cases. In some cases, the infection may completely resolve although in other dogs, especially if there is an underlying cause, long-term treatment may be needed.