Malassezia spp

From Cow
Malassezia pachydermatis under light microscopy

Malassezia spp are normal commensal yeast (fungus) of skin and is associated with otitis externa in cattle.

Clinically affected cattle often have pendulous ears, such as Zebu breeds. It is more common in older cattle in tropical and subtropical regions worldwide.

Species which are pathogenic to cattle include:

  • Malassezia pachydermatis[1]
  • Malassezia sympodialis[2]
  • Malassezia globosa
  • Malassezia slooffiae
  • Malassezia furfur[3]

A particularly low prevalence of Malassezia is found in Holstein cows, correlating with the open, air-exposed ears of this breed.

Diagnosis is based on presenting clinical signs of otitis externa, often with a characteristic smelly, greasy feel, accompanied by laboratory isolation of the yeast from samples. Species identification can now be done via PCR assays[4].

A differential diagnosis would include other dermatophytes such as Microsporum spp and Trichophyton spp and secondary to ticks (Otobius spp)

Treatment can be problematic as lengthy antifungal therapy (e.g. itraconazole suspensions or parenteral) is required.

References

  1. Duarte ER et al (2002) Identification of atypical strains of Malassezia spp. from cattle and dog. Can J Microbiol 48(8):749-752
  2. Duarte ER et al (2003) Factors associated with the prevalence of Malassezia species in the external ears of cattle from the state of Minas Gerais, Brazil. Med Mycol 41(2):137-142
  3. Duarte EP et al (1999) Prevalence of Malassezia spp. in the ears of asymptomatic cattle and cattle with otitis in Brazil. Med Mycol 37(3):159-162
  4. Duarte ER & Hamdan JS (2010) RAPD differentiation of Malassezia spp. from cattle, dogs and humans. Mycoses 53(1):48-56