700 DISEASES/DISORDERS
Ischemic dermatopathy:
Dermatomyositis in predisposed breeds – see Chapter 20 (Figures 48.10–48.12)
Vaccine induced: 2–6 months post vaccination (most often rabies); progressive,
noninflamed alopecia beginning at the site of injection; may be associated with
generalized symptoms (Figures 48.13, 48.14)
Idiopathic – not associated with vaccination.Causes and Risk Factors
Systemic lupus erythematosus
Cold agglutinin disease
Frostbite
Disseminated intravascular coagulopathy
Lymphoreticular neoplasia
Drug reactions, e.g., itraconazole-induced necrotizing vasculitis
Post vaccination
Spider bites
Immune-mediated disease
Erythema nodosum-like panniculitis
Rheumatoid arthritis
Rocky Mountain spotted fever
Staphylococcal hypersensitivity
Food hypersensitivity causing urticarial vasculitis
FeLV- and FIV-associated vasculitis in cats
50% of all cases are idiopathic
DIFFERENTIAL DIAGNOSIS
Ear margin seborrhea
Chemical or thermal burn
Coagulopathy
Toxic epidermal necrolysis
Erythema multiforme
Ulcerative dermatosis of collies and shelties
Deep pyoderma
Sepsis
DIAGNOSTICS
Diascopy: erythema that does not blanch with pressure from a glass slide indicates
hemorrhage into the skin (Figure 48.15).
CBC: thrombocytopenia, anemia – dependent on the underlying cause.
Immunodiagnostics: ANA titer, Coombs test, and cold agglutinin tests.