Pulmonary arteriovenous malformation in two adult alpacas (Vicugna pacos)

Abstract

Two cases of pulmonary vascular anomaly in unrelated adult alpacas (Vicugna pacos) are described. In the first case, a 9-year-old intact male alpaca presented at Oregon State University Veterinary Teaching Hospital with bilateral epistaxis and died the subsequent day following severe hemorrhage from the mouth and nostrils. At necropsy, a tortuous vascular lesion was identified in the right cranial lung lobe, associated with hemorrhage into airways. In the second case, a 2-year-old female alpaca presented with postpartum anorexia, opisthotonus, and recumbency. In this second case, a similar vascular lesion was identified in the right cranial lung lobe but without associated hemorrhage. Histopathological examination of the lesion in both cases revealed numerous dilated, irregular blood vessels with marked variation in wall thickness within vessels, surrounded by foci of extramedullary hematopoiesis. Diagnoses of locally extensive pulmonary vascular anomalies (arteriovenous malformations) were made.

Diseases of the Cardiovascular and Hemolymphatic Systems

“…21 On the basis of the predominance of tunica media over tunica adventitia, the abnormal vessels were judged to be arterial in origin. The older alpaca had severe bilateral epistaxis and pulmonary hemorrhage linked to rupture of one of these vessels.…”

A bronchopulmonary artery fistula in a horse

“…Pulmonary vascular anastomosis rarely occurs in animals, and only 3 cases have been reported. Spontaneous cases of pulmonary vascular anastomosis have been reported in a dog [8] and an alpaca [10], and the surgical creation of both a pulmonary arteriovenous anastomosis and a cavopulmonary anastomosis was described in a lamb [1]. In horses, vascular anastomoses have been reported in several organs, including the skin [12], hoof [9], and testis [4]; however, no cases of vascular anastomoses in the lungs have been reported.…”

“…Histopathologically, the lesion in the left anterior lobe was composed of two different types of blood vessels, and the walls of the blood vessels varied in thickness, due to the presence of elastic fibers and fibromuscular hyperplasia in the intima and increased fibrous density and smooth muscle hyperplasia in the tunica media. These histological findings were considered to reflect changes in the bloodstream and blood pressure [3,10]. Furthermore, the presence of hyperplastic changes in the vascular walls of two different types of blood vessel was suggestive of an anastomosis between the blood vessels.…”