CHAPTER 21 DERMATOPHYTOSIS 321
SIGNALMENT/HISTORY
Cats: more common in long-haired breeds with increased persistent subclinical
infection.
Clinical signs are more common in young and older animals.
Lesions begin as focal alopecia or a poor hair coat.
A history of previously confirmed infection, exposure to an infected animal or envi-
ronment (e.g., a cattery) increases risk of disease.
Causes
Cats:M. canismost common organism.
Dogs:M. canis,M. gypseum,andT. mentagrophytes; incidence of each organism varies
geographically.
Risk Factors
Immunocompromised condition caused by disease or medications (corticosteroids).
FIV infection (three times higher prevalence).
High population density (shelters).
Poor nutrition.
Poor management practices.
Lack of an adequate quarantine period.
Excessive bathing and grooming.
CLINICAL FEATURES
Varies from a nonclinical carrier state to patchy alopecia, which may rapidly progress
to generalized lesions (Figures 21.1–21.5).
Lesions may resolve spontaneously as hair follicles enter telogen.
Classic circular area of erythema, alopecia, and scale: common in people, rare in ani-
mals (Figures 21.6, 21.7).
Scales, erythema, hyperpigmentation, and pruritus: variable.
Granulomatous lesions (pseudomycetoma) or kerions may occur (oftenM. gypseum)
(Figure 21.8).
Folliculitis (Figure 21.9).
Miliary dermatitis in cats.
Clawbed inflammation and claw deformity (Figure 21.10).
Facial folliculitis and furunculosis may mimic an autoimmune disease.
Zoonotic (Figures 21.11, 21.12).
Acantholytic dermatophytosis; mimics pemphigus complex; oftenTrichophytonspp.
(Figure 21.13).