title: Pathological features of systemic necrotizing vasculitis (polyarteritis nodosa) in sheep.
abstract: Polyarteritis nodosa (PAN) is a systemic vasculitis of unknown aetiology affecting small- and medium-sized arteries of multiple organ systems without involvement of pulmonary arteries. This report describes four cases of PAN in sheep from different flocks. Three of these animals displayed clinical signs of locomotor disturbance. Gross necropsy findings included bilateral nodular thickening of vessels together with thromboses and aneurysms at several locations. Microscopically, small- to medium-sized arteries of the kidneys, ovary, uterus and skin were consistently involved and other locations were affected less frequently. Arteries within the lung were normal in all animals. Vascular lesions were characterized by focal fibrinoid necrosis, rupture of the internal elastic lamina and transmural infiltration of mononuclear inflammatory cells, extending into the perivascular tissue. In the kidney, many arteries showed narrowing or occlusion of the lumen and marked fibrosis. The distribution of arterial lesions was segmental, showing alternation of affected and microscopically normal areas. Immunohistochemical studies did not identify immune complex deposition. The inflammatory infiltrates were composed of T lymphocytes and macrophages, suggesting that a cell-mediated immune response may be involved in the pathogenesis of this disease.
authors.affiliation: Departamento de Sanidad Animal (Anatomía Patológica), Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana, s/n, 24071 León, Spain. mcfere@unileon.es
authors.forename: M C
authors.initials: MC
authors.lastname: Ferreras
authors.forename: J
authors.initials: J
authors.lastname: Benavides
authors.forename: M
authors.initials: M
authors.lastname: Fuertes
authors.forename: C
authors.initials: C
authors.lastname: García-Pariente
authors.forename: M
authors.initials: M
authors.lastname: Muñoz
authors.forename: L
authors.initials: L
authors.lastname: Delgado
authors.forename: L
authors.initials: L
authors.lastname: Polledo
authors.forename: J
authors.initials: J
authors.lastname: González
authors.forename: J F
authors.initials: JF
authors.lastname: García Marín
authors.forename: V
authors.initials: V
authors.lastname: Pérez
mesh_terms: D000818:Animals; D010488:Polyarteritis Nodosa / Q000473:pathology / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000473:pathology*