chapter 21 Dermatophytosis......................................
DEFINITION/OVERVIEW
Cutaneous fungal infection affecting the cornified regions of hair and claws and the
superficial layers of the skin (ringworm).
Commonly isolated organisms:Microsporum canis,Trichophyton mentagrophytes,and
Microsporum gypseum.
Source ofM. canisis usually an infected cat.
Source ofT. mentagrophytesis often direct or indirect contact with rodents.
Source ofM. gypseumis from soil – digging in contaminated areas.
Dermatophytosis is a zoonotic disease.
ETIOLOGY/PATHOPHYSIOLOGY
Exposure to or contact with a dermatophyte does not necessarily result in an infec-
tion.
Infection may not result in overt clinical signs.
Dermatophytes grow in the keratinized layers of hair, claws, and skin; do not thrive
in living tissue or persist in the presence of severe inflammation; incubation period
is 1–4 weeks.Affected animals may remain asymptomatic carriers for a prolonged period of time;
some animals never become symptomatic.
Corticosteroids can modulate inflammation and prolong the infection.
Incidence/Prevalence
Lesions can mimic many dermatologic conditions.
Infection rates vary widely, depending on the population studied.
Catteries and shelters are at risk.
Incidence of asymptomatic carriage as well as clinical infection is higher in hot and
humid regions.
Incidence rates of geophilic dermatophytes vary geographically.
Dermatophytes spread between animals and people via direct contact with infected
hair and/or scale (directly or by fomite).
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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