Content continues after advertisement

Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats

Ashley E. Detwiler, DVM, DACVD, MedVet, Cincinnati, Ohio

Dermatology

|June 2017|Peer Reviewed|Web-Exclusive

Sign in to Print/View PDF

Dermatophytosis is a pathogenic, keratin-digesting, fungal infection of the hair, outermost layer of the skin (stratum corneum), and claw.1-5 Although uncommon, infection can also occur in the deep layer of the skin and subcutaneous tissue.1 In dogs and cats, dermatophytosis is most often caused by Microsporum canis, M gypseum, or Trichophyton mentagrophytes.1-5 

All three organisms are zoonotic,1-5 with transmission most often linked to M canis (which also is zoophilic, as elaborated later). Of note, because M gypseum inhabits soil, it is zoonotic and geophilic1,4; whereas T mentagrophytes is found on rodents or in their environment, making this organism also zoophilic.1,4 

Dermatophytosis is acquired following contact with

  • Infected hair or scale from animals
  • Fomites
  • Spores residing in soil 
  • Spores in other outdoor or indoor environments

Individuals at increased risk of infection include1

  • Young
  • Geriatric 
  • Immunocompromised 

In Persian cats and Yorkshire terriers, genetics also may be involved, as both breeds commonly have repeat infections or difficulty clearing infections.1,2 

The preference of M canis for an animal host makes this organism a zoophilic dermatophyte1,4; it also is the most frequent cause of dermatophyte infection in small animals and can be carried by asymptomatic cats.1,5 M canis infection is particularly important to avoid in catteries, shelters, and multipet environments or households.2,4,6 

Clinical Presentation

Dermatophytosis can be focal or generalized1,3 affecting

  • Face
  • Ears 
  • Legs 
  • Tail
  • +/- trunk 

Most patients have little to no evidence of pruritus, although chronic and extensive cases can be severely pruritic. 

On skin, clinical presentation most often involves1-5

  • Partial to complete alopecia
  • Scale/dry or greasy seborrhea
  • Erythema
  • Papules
  • Pustules
  • Crusts
  • Epidermal collarettes (ringlike appearance)
  • +/- feline miliary dermatitis (crusted papules)

Nodules, draining tracts, feline chin acne, paronychia (inflammation of the claw fold), onychomycosis (fungal infection of the claw), or onychodystrophy (abnormal growth of the claw) occur less commonly.1-5

Global Relevance 

Dermatophytosis occurs worldwide; however, prevalence of specific organisms varies by region.3,4 Because dermatophytosis is not a reportable disease, the overall incidence remains unknown.3 Dermatophytes grow best in warm, humid environments, including tropical and subtropical geographic areas.4 Risk for disease transmission increases with crowding, close contact, skin trauma, or contact with chronic moisture.3

10  Questions
Multiple Choice Questions
Score 0/10

Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats

Take this quiz by answering the following multiple choice questions.
1/10  Questions
Score
Score 0/10

Which of the following organisms is most likely depicted on this dermatophyte medium (DTM) culture plate?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
2/10  Questions
Score
Score 0/10

Based on this DTM culture plate, which organism is most likely depicted?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
3/10  Questions
Score
Score 0/10

Which of the 3 species being discussed is shown on this culture plate?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
4/10  Questions
Score
Score 0/10

Macroconidia and microconidia are depicted microscopically on low power field (lpf) of 4× to 10× via acetate tape cytology examination using lactophenol cotton blue or new methylene blue stain, following culture and colony growth. 

Which dermatophyte species is microscopically shown in this figure?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
5/10  Questions
Score
Score 0/10

Macroconidia and microconidia are depicted microscopically on low power field (lpf) of 10× and high power field (hpf) of 50× via acetate tape cytology examination using lactophenol cotton blue or new methylene blue stain, following culture and colony growth. 

Which dermatophyte species is shown?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
6/10  Questions
Score
Score 0/10

Macroconidia or microconidia are depicted microscopically on low power field (lpf)10× and high power field (hpf) 50× via acetate tape cytology examination using lactophenol cotton blue or new methylene blue stain, following culture and colony growth. 

Which species is microscopically shown here? 

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
7/10  Questions
Score
Score 0/10

Beyond fungal culture, additional diagnostic testing may assist clinicians in identifying dermatophytosis. 

Which of the following diagnostic tests is depicted in Figure 7?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
8/10  Questions
Score
Score 0/10

Which diagnostic test is depicted here?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
9/10  Questions
Score
Score 0/10

Which of the following diagnostic tests is depicted in Figure 9?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
10/10  Questions
Score
Score 0/10

Which diagnostic test is depicted in Figure 10?

Clinician's Brief
Select one of the above choices and click submit.
Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats
10/10  Questions
Multiple Choice Questions
Score 0/10

Image Quiz: Diagnosing Dermatophytosis in Dogs & Cats

Final score
0 of 10

References and Author Information

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Clinician's Brief may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.

Podcasts

Clinician's Brief:
The Podcast
Listen as host Alyssa Watson, DVM, talks with the authors of your favorite Clinician’s Brief articles. Dig deeper and explore the conversations behind the content here.
Clinician's Brief provides relevant diagnostic and treatment information for small animal practitioners. It has been ranked the #1 most essential publication by small animal veterinarians for 9 years.*

*2007-2017 PERQ and Essential Media Studies

© 2023 Educational Concepts, L.L.C. dba Brief Media ™ All Rights Reserved. Terms & Conditions | DMCA Copyright | Privacy Policy | Acceptable Use Policy