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MALASSEZIA DERMATITIS

Note for Pet Owners:

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

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Description
Malassezia dermatitis is a secondary inflammatory skin disease caused by the presence of a yeast - Malassezia pachydermatis in dogs, Malassezia sympodialis in cats.

Cause
 Malassezia pachydermatis (also known as Pityrosporum pachydermatis or Pityrosporum canis) is a yeast which is a commensal and it can be found on the skin or in the ear canals, and also in the rectum and vagina as well as in the anal sacs of normal dogs. However, the organism causes disease when changes in the skin allow it to become a "facultative pathogen".

Malassezia sympodialis has been reported to cause dermatitis in cats

Breed Occurrence
The following breeds of dog are reported to have an increased risk of developing Malassezia dermatitis : the Australian Terrier, Bassett Hound, Chihuahua, Dachshund, German Shepherd Dog, Maltese, Newfoundland, Poodle, Silky, Shetland Sheepdog, Springer Spaniel, and  the West Highland White Terrier  

Malassezia dermatitis has also been reported to occur in cats

Signs

The typical clinical signs associated with Malassezia dermatitis in dogs are :

  • Alopecia
  • Erythema
  • Greasy coat
  • Hyperpigmentation
  • Increased scale production
  • Lichenification
  • Pruritus
  • Seborrhoeic smell

Distribution of the lesions may be :

  • Focal
  • Multifocal
  • Generalised

and they most often affect the :

  • Abdomen - ventral
  • Axillae
  • Ear pinnae
  • Face
  • Feet
  • Front legs
  • Skin folds

In cats the typical signs are :

  • Acne
  • Generalised exfoliation

Complications
The presence of concurrent chronic disorders

Diagnosis
Skin cytology is recommended to confirm the diagnosis and suitable samples may be collected by a variety of techniques including :

  • Direct impression smears onto glass slides
  • Swabbing
  • Sticky tape collection
  • Skin scraping
  • Biopsy

The yeast can be identified under a microscope by it's characteristic appearance :

  • No mycelia
  • Lipophilic (stains blue with Dif QuikTM)
  • An elongated oval (peanut) shape
  • A thick wall
  • Budding at one end

 

Picture reproduced with permission of the Publishers from Skin Diseases of the Dog and Cat by Harvey and McKeever - available from Provet's On-line Discount Bookshop Click Here

However, isolation of the yeast Malassezia pachydermatis from the skin of a dog  is not necessarily significant because the organism is a commensal.

There are circumstances when it is likely to have an important role to play in disease, notably in association with the following conditions :

Treatment

Any primary underlying disease must be treated. In addition, specific therapy can be given to treat the Malassezia :

  • Ketoconazole - 10mg/kg body weight by mouth once daily for 10-14 days, unless the patient has impaired liver function, in which case alternate drugs have been  recommended - eg fluconazole or itraconazole 
  • Shampoos - degreasing and antifungal

Anti-inflammatory drugs such as corticosteroids may not provide relief for the pruritus seen in patients with Malassezia dermatitis

Prognosis
Good providing an underlying cause can be identified and treated

Long term problems

Recurrent infections if the underlying problem is not treated successfully

 

Updated October 2013