Page 1284 - Veterinary Immunology, 10th Edition

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FIG. 38.10 An extramural coronary artery from a Beagle suffering
from juvenile polyarteritis. This medium-sized muscular artery is
characterized by medial necrosis, ruptured elastic laminae, and
severe perivascular accumulations of neutrophils, lymphocytes, and
macrophages. (H&E stain.) (From Snyder PW, Kazacos EA, Scott-Moncrieff
JC, et al: Pathologic features of naturally occurring juvenile polyarteritis in beagle
dogs, Vet Pathol 32:337-345, 1995.)

Polyarteritis nodosa occurs in humans, pigs, dogs, and cats. It is
characterized by a widespread, focal necrosis of the media of small-
and medium-sized muscular arteries. The lesions are found in
many organs, especially in the kidney. Vessels in the skin are rarely

involved.
On occasion, focal vascular lesions characterized by neutrophil
infiltration may develop in small blood vessels throughout the
body, but especially in skin. Affected dogs have mucocutaneous

ulcers, bullae, edema, polyarthropathy, myopathy, anorexia,
intermittent fever, and lethargy. Although called hypersensitivity
vasculitis, a foreign antigen can be found in only a small proportion
of cases. For this reason, a better name for this condition may be

leukocytoclastic vasculitis. The cause or causes of polyarteritis
nodosa and hypersensitivity vasculitis are unknown. Their
histopathology suggests that they are a form of type III

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