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The microbial environment of the ear canal in health and disease

J J Kowalski1

  • 1Department of Veterinary Clinical Sciences, Ohio State University, College of Veterinary Medicine, Columbus.

The Veterinary Clinics of North America. Small Animal Practice
|July 1, 1988
PubMed

Insights

Otitis externa in dogs and cats is commonly caused by Malassezia yeast and bacteria like staphylococci and Pseudomonas. Early diagnosis via smears aids treatment, while cultures are vital for complex or recurring infections.

Area of Science:

  • Veterinary Dermatology
  • Microbiology

Background:

  • Otitis externa is a prevalent condition in domestic animals, particularly dogs.
  • The yeast Malassezia canis and various bacteria are frequently implicated in ear infections.

Purpose of the Study:

  • To identify the most common causative agents of otitis externa in dogs and cats.
  • To outline diagnostic approaches and treatment considerations for these infections.

Main Methods:

  • Microscopic examination of ear canal smears for rapid diagnosis.
  • Bacterial and yeast culture and susceptibility testing for recurrent or refractory cases.

Main Results:

  • Malassezia canis is the most frequent yeast isolate.
  • Coagulase-positive staphylococci are the most common bacteria, often co-infecting with M. canis.
  • Pseudomonas aeruginosa and Proteus are significant gram-negative pathogens, while other bacteria like E. coli and Streptococcus are also identified.

Conclusions:

  • Cytological examination of ear smears offers a rapid diagnostic method for empiric treatment initiation.
  • Culture and susceptibility testing are crucial for managing chronic, recurrent, or complicated otitis externa, especially those involving gram-negative bacteria.
  • Consultation with a microbiology laboratory is recommended for practices lacking in-house diagnostic capabilities.

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