Small Animal Dermatology, 3rd edition

620 DISEASES/DISORDERS

Most cases euthanized within 8 weeks of developing dermatitis

Hair loss: rapidly progressive with sudden onset leading to total loss in

affected region; primarily ventral distribution (ventral trunk, medial aspect

of limbs) (Figure 41.12)

Some affected cats may be reluctant to walk, owing to painful fissuring of

the footpads

Hairs epilate easily

Severe alopecia: ventral neck, abdomen, and medial thighs

The stratum corneum may “peel,” leading to a glistening appearance to the

skin (Figure 41.13)

Alopecic skin is shiny, inelastic and thin, but not fragile

Pruritus: variable; sometimes with excessive grooming

Gray lentigines may develop in alopecic areas

Footpads may be fissured and/or scaly, often painful

May have secondaryMalasseziaovergrowth

Exfoliative dermatitis associated with thymoma:

Slowly progressive scaling dermatitis

Cats present with skin lesions and no evidence of neoplasia

Systemic signs develop late in the course of disease; coughing, dyspnea,

anorexia, lethargy

Lesions often begin on the head and neck; become generalized (Fig-

ure 41.14)

Large, nonadherent, white scales and crusts (Figure 41.15)

Erythema mild initially and then becomes severe

Brown waxy deposits adhere around the eyes and lips as well as the ear

canal

Usually nonpruritic unless associated with secondaryMalassezia over-

growth

Rare associated myasthenia gravis and megaesophagus.

DIFFERENTIAL DIAGNOSIS

 Canine preneoplastic dermatoses:
Actinic keratoses: bacterial furunculosis, lichenoid keratosis, squamous cell car-

cinoma, topical drug eruption, severe contact dermatitis

Cutaneous lymphocytosis: epitheliotropic lymphoma, lymphocytic leukemia

with cutaneous involvement, hypersensitivity reaction, drug eruption, bacterial

folliculitis

Cutaneous mastocytosis: hypersensitivity reaction, drug eruption, bacterial fol-

licultitis, mast cell tumor

Nodular fasciitis: infectious granuloma, sterile granuloma, local trauma, dermal

neoplasia, fibroma, fibrosarcoma, spindle cell lipoma.

 Canine paraneoplastic dermatoses:
Cutaneous (primary nodular) amyloidosis:dermal neoplasia or cyst, infectious

granuloma, sterile granuloma, pyogranulomatous dermatitis