666 DISEASES/DISORDERS
SIGNALMENT/HISTORY
Primarily old dogs; mean age 10 years; rare in cats.
Males overrepresented.
May have a heritable component in some breeds (shih tzu).
Predilection for medium and small breeds: West Highland white terrier, Scottish ter-
rier, American cocker spaniel, Shetland sheepdog, Lhasa apso, border collie; syn-
drome also identified in large breeds.Cutaneous lesions often precede systemic symptoms.
CLINICAL FEATURES
Progressive development of erythema, hyperkeratosis, and exudation at the margins
of the footpads (Figure 45.1).
Crusting, ulcerative, and painful dermatitis (Figures 45.2, 45.3).
Lesions affect the mucocutaneous junctions of lips, eyes, and anus; develop at the
same time as or immediately following footpad lesions (Figure 45.4).
Skin lesions also pronounced in areas of trauma: muzzle, distal limbs, elbows, foot-
pads (Figure 45.5).
Fissuring and severe crusting of footpads result in pruritus and pain.
Hyperpigmentation and lichenification common with chronicity.
Secondary bacterial folliculitis andMalasseziadermatitis common.
Lesions develop on pressure points, pinnae, and external genitalia.
Dermatitis often precedes systemic symptoms by weeks.
Systemic signs include lethargy, polyuria, polydipsia (when associated with diabetes
mellitus), anorexia, and weight loss.
Poor to grave prognosis.
DIFFERENTIAL DIAGNOSIS
Pemphigus foliaceus
Zinc-responsive dermatosis
Systemic lupus erythematosus
Erythema multiforme
Drug eruption
Generic dog food dermatosis
Irritant contact dermatitis
Demodicosis
Dermatophytosis
Vasculitis
Epitheliotropic lymphoma