Peer Reviewed

Points to Remember

  • Wood’s lamp examinations are effective only as a screening tool for M canis infections. Negative fluorescence does not rule out dermatophytosis.
  • Wood’s lamp examinations are cost- and time-effective when examining known culture-positive animals (M canis) or highly suspect animals (eg, cats with skin lesions).
  • Wood’s lamps can be used in any species susceptible to M canis infections, but because dermatophytosis is more common in cats and more pleomorphic in presentation, it is considered a core diagnostic test in cats with skin disease.
  • Fungal culture is always recommended to confirm the infection.
  • Allow the lamp to warm up for 3 to 5 minutes to be sure it is being used at full power. Perform the test in complete darkness to allow for the examiner’s retinas to be totally dark-adapted. The gradual “development” of fluorescence is the result of one’s eyes becoming adapted to the light.
  • Most mistakes made with the Wood’s lamp are due to failure to allow the lamp to warm up completely, not having the room dark enough, not taking enough time to perform a complete examination, and not allowing time for the examiner’s eyes to adapt to darkness.

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