Felis ISSN 2398-2950

Malassezia dermatitis

Contributor(s): David Godfrey, Rosanna Marsella, Charlie Walker

Introduction

  • Rarely recognized but probably is underdiagnosed.
  • Cause: not definitely known but Malassezia pachydermatis Malassezia pachydermatis and Malassezia sympodialis are suspected to be the usual pathogens. It may often be a complication of another dermatosis.
  • Signs: otitis externa, seborrheic dermatitis, claw fold deposits.
  • Diagnosis: cytopathology.
  • Treatment: topical and or systemic antifungal agents.
  • Prognosis: good unless severe underlying condition. Recurrence is common if underlying cause is not identified.
    Print off the owner factsheet on Malassezia Malassezia to give to your client.

Pathogenesis

Etiology

  • Probably overgrowth of commensal organisms (Malassezia pachydermatis  Malassezia pachydermatis and Malassezia sympodialis, M. globosa, M. furfurM. nana and M. slooffiae due to factors altering the skin surface microclimate. 
  • Possibly (but this is untested) underlying immunosuppressive condition may be involved, eg diabetes mellitus Diabetes mellitus, neoplasia, feline immunodeficiency virus Feline immunodeficiency virus, allergies, endocrinopathies and genetics.

Predisposing factors

General

  • Genetic predisposition - higher commensal populations seen in Sphynx Sphynx and Devon Rex Devon Rex breeds. 
  • Population size vary between individuals, breeds and anatomical sites.  
  • Immunosuppression.

Specific

Pathophysiology

  • Based on conjecture and data from other species. 
  • Commensal yeast populations provide a reservoir that might proliferate and/or induce an inflammatory response under the influence of various predisposing factors: 
    • Metabolic activities of the yeast - expression of cell wall and secreted virulence attributes. 
    • Interactions with other skin commensals especially Staphylococci Staphylococcus spp
    • The host’s innate and adaptive immune defensive responses. 
  • More studies required to define mechanisms of transition between commensalism and disease causation. 
  • Unlike dogs, Malassezia hypersensitivity has not been documented in cats. 

Timecourse

  • Weeks to months (or lifelong).

Epidemiology

  • Not infectious. 
  • Probably unknown factors  →  changes in the skin surface microclimate and possibly decreased skin defenses. 
  • ± Factors that increase skin surface moisture such as ptyalism, food contamination, skin and body folds (brachycephalic breeds, obesity) may be involved. 

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bond R, Morris D O, Guillot J et al (2020) Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats. Clinical Consensus Guideline of WAVD. Vet Dermatol 31, 27-4e PubMed.


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