Immune mediated Type III hypersensitivity. Primary bacterial skin disease with bacterial antigens deposited locally in vessel walls. Bacterial septicemia or systemic infection with agents that have a predilection for endothelial cells lead to direct endothelial damage and thrombosis. Leukocytes focused on vessel walls. Possible fibrinoid necrosis of vessel wall, leukoclastic vasculitis, hemorrhage, fibrin deposition, possible thrombosis, infarction or evidence of ischemia.
Hemorrhages can vary from petechial to ecchymotic.
Chronic, less complete ischemia may lead to atrophy of adnexa and other dermal structures. High Power Gross Lesions example from a pig that died from Erysipelothrix rhusiopathiae septicemia. Canine Lupus Erythematosus. Weiser IB, et al. Dermal necrosis associated with Rocky Mountain spotted fever in four dogs.