Thoracic Aortic Rupture and Aortopulmonary Fistulation in the Friesian Horse: Histomorphologic Characterization

M Ploeg, V Saey, C Delesalle, A Gröne, R Ducatelle, M de Bruijn, W Back, P R van Weeren, G van Loon, K Chiers

    Research output: Contribution to journalArticleAcademicpeer-review

    Abstract

    Aortic rupture in horses is a rare condition. Although it is relatively common in the Friesian breed, only limited histopathologic information is available. Twenty Friesian horses (1-10 years old) were diagnosed with aortic rupture by postmortem examination. Ruptured aortic walls were analyzed with histology and immunohistochemistry. Based on the histologic and immunohistochemical findings, these cases were divided into 3 groups: acute (n = 4, 20%), subacute (n = 8, 40%), and chronic (n = 8, 40%). Features common to samples from horses in all groups included accumulation of mucoid material; disorganization and fragmentation of the elastic laminae; aortic medial smooth muscle hypertrophy; and medial necrosis of varying degrees, ranging from mild and patchy in the acute cases to severe midzonal necrosis in the chronic cases. Inflammation, most likely secondary to medial necrosis, varied from predominantly neutrophilic infiltrates in the media and periadventitial tissue in the acute group to the presence of mainly hemosiderophages in the periadventitial tissue in the chronic group. Medial fibrosis with aberrant collagen morphology was seen in the subacute group and, more commonly, in the chronic group. Only minimal changes were seen in the aortic vasa vasorum. Smooth muscle hypertrophy and accumulation of mucoid material were not related to the age of the lesions. The findings of this study suggest that a connective tissue disorder affecting elastin or collagen in the aortic media is potentially the underlying cause of aortic rupture in Friesian horses.

    Original languageEnglish
    Pages (from-to)152-159
    JournalVeterinary Pathology
    Volume52
    Issue number1
    Early online date16 Apr 2014
    DOIs
    Publication statusPublished - Jan 2015

    Keywords

    • Friesian horses
    • aorta
    • histology
    • immunohistochemistry
    • laminar medial necrosis
    • aortopulmonary fistulation
    • pseudoaneurysm
    • vasa vasorum

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