Equis ISSN 2398-2977

Malassezia dermatitis

Contributor(s): Beatrice Funiciello, Jeanette Bannoehr


  • Cause: Malassezia spp Malassezia spp.
  • Signs: pruritus, associated skin lesions include alopecia, erythema, crusting, ulceration, accumulation of greasy and waxy, often malodorous, material.
  • Diagnosis: cytology. Culture or molecular methods for species identification. Organisms may be found in histological sections.
  • Treatment: topical antifungals: miconazole 2% shampoo Miconazole, chlorhexidine/miconazole 2% shampoo or chlorhexidine 4% shampoo Chlorhexidine. Clinical improvement can be expected after 7-14 days of topical treatment, but correction of underlying factors is needed for long-term control and to prevent recurrence. Hygiene of the intermammary, preputial and interiginous regions to avoid excessive accumulation of debris and excessive moisture is crucial.
  • Prognosis: excellent but risk of recurrence.



  • Malassezia spp Malassezia spp: Malassezia furfur, M. slooffiae, M. obtusa, M. globosa, M. restricta, M. equina, M. sympodialis, M. nana and M. pachydermatis have been isolated from the skin, mucosae and ear canals of healthy horses and may uncommonly cause dermatitis. Malassezia dermatitis is usually secondary to other underlying conditions such as excessively moist intertriginous skin, pastern dermatitis, alopecia areata Hair: alopecia areata.

Predisposing factors


  • Local or systemic immunocompromise.
  • Chronic glucocorticoid treatment.


  • Moist skin, especially in skin folds.
  • Other alterations in cutaneous microenvironment: pH, air circulation, composition of the skin microbiome, presence of cerumen or debris, sebum production, keratinization defects, hormonal changes.
  • Other skin diseases: pastern dermatitis, alopecia areata Hair: alopecia areata.


  • The healthy skin environment is resistant to development of Malassezia spp Malassezia spp dermatitis.
  • In damaged skin, enzymes produced by the organism may target keratinocytes, creating inflammation, pruritus and activating both cell-mediated and humoral host responses.
  • Malassezia hypersensitivity may occur in some horses.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Aldovrandi A L, Osugui L & Dall’Acqua Coutinho S (2016) Is Malassezia nana the main species in horses’ ear canal microbiome? Braz J Microbiol 47 (3), 770-774 PubMed.
  • Azarvandi A, Khosravi A R, Shokri H et al (2016) Presence and distribution of yeasts in the reproductive tract in healthy female horses. Equine Vet J 49 (5), 614-617 PubMed.
  • Bond R (2002) Malassezia spp. in horses: background to an evolving subject in dermatology. Equine Vet Educ 14 (3), 123-124 VetMedResource.
  • Cabañes F J, Theelen B, Castellá G & Boekhout T (2007) Two new lipid-dependent Malassezia species from domestic animals. FEMS Yeast Res (6), 1064-1076 PubMed.
  • Cafarchia C & Otranto D (2008) The Pathogenesis of Malassezia Yeasts. Parasitol 50 (1-2), 65-67 PubMed.
  • Cafarchia C, Figueredo LA & Otranto D (2013) Fungal diseases of horses. Vet Microbiol 167 (1-2), 215-234 PubMed.
  • Castellá G, Hernández J J & Cabañes F J (2005) Genetic typing of Malassezia pachydermatis from different domestic animals. Vet Microbiol 108 (3-4), 291-296 PubMed.
  • Crespo M J, Abarca M L & Cabañes F J (2002) Occurrence of Malassezia spp. in horses and domestic ruminants. Mycoses 45 (8), 333-337 PubMed.
  • Kim D Y, Johnson P J & Senter D (2011) Diagnostic Exercise: Severe Bilaterally Symmetrical Alopecia in a Horse. Vet Pathol 48 (6), 1216-1220 VetMedResource.
  • Nell A, James S A, Bond C J, Hunt B & Herrtage M E (2002) Identification and distribution of a novel Malassezia species yeast on normal equine skin. Vet Rec 150 (13), 395-398 PubMed.
  • Paterson S (2002) Identification of Malassezia from a horse’s skin. Equine Vet Educ 14 (3), 121-125 VetMedResource.
  • Shokri H (2016) Occurrence and distribution of Malassezia species on skin and external ear canal of horses. Mycoses 59 (1), 28-33 PubMed.
  • White S D, Vandenabeele S I J, Drazenovich N L & Foley J E (2006) Malassezia Species Isolated from the Intermammary and Preputial Fossa Areas of Horses. J Vet Intern Med 20 (2), 395-398 PubMed.
  • White S D (2015) A diagnostic approach to the pruritic horse. Equine Vet Educ 27 (3), 156-166 VetMedResource.

Other sources of information

  • Scott D W & Miller W H (2011) Fungal Skin Diseases. In: Equine Dermatology. 2nd edn. Saunders, USA. pp 171-211.
  • Boekhout T Guého E, Mayser P & Velegraki A (2010) Malassezia and the Skin. Springer, Germany.
  • Knottenbelt D C (2009) Fungal diseases. In: Pascoe’s Principles and Practice of Equine Dermatology. 2nd edn. Ed: D C Knottenbelt. Saunders, USA. pp 167-185.