CHAPTER 43 SEBACEOUS ADENITIS, GRANULOMATOUS 649
Change in hair from wavy to straight (Figure 43.3).
Symmetric, partial to diffuse alopecia (Figures 43.4–43.6).
Dull brittle hair.
Follicular casts: hairs with tightly adherent silver-white scale (keratin collaring) (Fig-
ures 43.7, 43.8); often first observed along dorsal midline and head.
Tufts of matted hair; loss of hair and matted hair with scale on the tail give the appear-
ance of a rat tail.
Secondary bacterial folliculitis, pruritus, and malodor (Figure 43.9).
Short-Coated Dog Breeds
Alopecia: “moth-eaten” pattern of coalescing circular to serpiginous lesions.
Lesions may be erythematous.
Scaling: fine and adherent.
Affects the trunk, head, and pinnae (Figures 43.10–43.14).
Secondary bacterial folliculitis rare.
Cats
Initial lesions on the head and pinnae; may become generalized.
Hypotrichosis progressing to alopecia and scaling.
Black waxy debris noted along the eyelid margins, nasal folds, perioral.
Secondary bacterial folliculitis.
DIFFERENTIAL DIAGNOSIS
Primary keratinization disorder
Bacterial folliculitis
Demodicosis
Dermatophytosis
Endocrine skin disease
Ichthyosis
Follicular dysplasia
Epitheliotropic lymphoma
Feline specific differentials: mural infiltrative folliculitis, feline exfoliative dermatitis,
pseudopelade, paraneoplastic syndrome (thymoma-associated exfoliative dermatitis).
DIAGNOSTICS
Skin scrapings: normal.
Dermatophyte culture: negative.
Endocrine function tests: normal.
Skin biopsies are diagnostic.