Intermittent Haemoptysis due to an Aortobronchial Fistula in a Warmblood Mare.

This research presents a case of a 7-year-old warmblood mare that displayed mild, episodic haemoptysis, or coughing up blood. The mare was found dead two weeks later, with post-mortem examination revealing a rarity: an aortobronchial fistula caused by an aortic aneurysm. This condition is rarely seen, even in humans, and the article documents the first known fatal case in an animal.

Clinical Presentation and Initial Findings

• The study detailed the presentation of a warmblood mare that started showing symptoms of intermittent haemoptysis, which is sudden, mild coughing up of blood.
• Upon clinical examination, no significant abnormalities were observed. However, further testing revealed mild anaemia, hypoalbuminaemia, and neutrophilia, indicating potential issues with blood and protein levels. Additionally, coagulation tests proved to be normal.
• The endoscopic examination uncovered unilateral pulmonary haemorrhage with blood clots in the bronchi and trachea.
• With these findings, treatment with antibiotics was initiated, and the horse was given stable rest.

Post-mortem Examination and Final Diagnosis

• The mare was discovered dead two weeks after the start of the symptoms, with blood and frothy sputum leaking from the nostrils.
• A post-mortem examination was conducted, revealing a large thoracic aortic aneurysm that was communicating with a pseudoaneurysm from which a fistula (an abnormal connection) had formed into a right bronchial branch.
• A microscopic examination of the aneurysm and the pseudoaneurysm revealed extensive medial fibrosis, degeneration, fragmentation, and mineralization of the elastic fibers, and mucoid material deposition in the tunica media. The pseudoaneurysm was found to be lined by collagen bundles, fibroblasts, and a small amount of adipose tissue.

Significance of the Study

• While aortobronchial fistula is a known condition in humans, usually associated with primary aortic pathology such as aneurysms, its occurrence in horses or any other animal species is yet unheard of. As such, this study represents the first documentation of a fatal aortobronchial fistula in a non-human.
• This discovery offers a potential new perspective in the diagnosis and treatment of similar symptoms in animals, as it warns of the potential of rare, fatal conditions.