Pathological changes in the lungs of a horse which had a history of intermittent nasal bleeding after exercise (abstract)

Authors: Pearce HE, Badcoe LM, Thompson KG
Publication: New Zealand Veterinary Journal, Volume 40, Issue 1, pp 37, Mar 1992
Publisher: Taylor and Francis

Animal type: Horse, Livestock
Subject Terms: Circulatory system/haematology, Ear/nose/throat, Exercise/fitness/athletic performance, Locomotor, Disease/defect, Pathology, Respiratory system
Article class: Abstract

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Abstract: A 4-year-old thoroughbred-cross gelding was presented with a history of intermittent nasal bleeding after exercise for the past 2 years.
Haemosiderin was observed in the cytoplasm of macrophages in cells obtained via a tracheobronchial aspirate from this gelding.
At necropsy the lungs failed to collapse and the caudodorsal regions of both caudal lung lobes were blue to blue-grey. There were some areas of brown discolouration of lung parenchyma in these caudodorsal regions of the caudal lung lobes. Mild, patchy emphysema was evident in the cranial lung lobes.
Histological sections of the lung revealed severe extensive haemosiderosis throughout the lung parenchyma of the caudal lung lobes, particularly the caudodorsal regions, but no haemosiderosis in sections from the cranial lung lobes. There was extensive collagen deposition around large, medium and small branches of both bronchial and pulmonary arteries. Staining of lung sections with Perl`s Prussian blue demonstrated an abundance of iron in collagen surrounding muscular arteries and macrophages throughout the parenchyma of the caudal lung lobes but not the cranial lung lobes. Mild peribronchial infiltrates of lymphocytes and occasional plasma cells and macrophages were observed in the lung from the affected horse and age-matched control horses.
The presence of an abnormal amount of collagen surrounding branches of the bronchial and pulmonary artery and in the interstitial tissue from the caudodorsal parts of the caudal lung lobes suggests that there had been healing and repair in these regions, possibly following mechanical stress leading to parenchymal tear and blood vessel damage.

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