Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. VIII. Conclusions and implications.
Abstract: This paper reviews a series of clinical, post mortem and imaging studies on exercise-induced pulmonary haemorrhage (EIPH) performed on 26 Thoroughbred racehorses. Post mortem techniques included routine gross, subgross and histological examination; coloured latex perfusions of pulmonary and bronchial circulations; and microradiography and computerised tomography scans of lungs with contrast injected vasculature. The major lesions were multiple, separate and coalescing foci of moderately proliferative small airway disease accompanied by intense neovascularisation of the bronchial circulation. As a result of bronchial artery angiogenesis, the systemic circulation dominated the vascular supply of the air exchange structures in affected areas, producing an apparent left to right shunt. Extensive areas of sequestered haemosiderophages indicated previous haemorrhage from vessels apparently supplied by the bronchial arteries. Diffuse and focal parenchymal destruction and connective tissue reactions in affected areas were considered to be secondary to localised haemorrhage and macrophage-induced damage. The aetiology of EIPH was not determined, but the multifocal, small airway-centred lesions indicated that low grade bronchiolitis, possibly of viral origin, was a factor. Gravitational effects also appear to contribute to dorsal distribution of the lesions. The mild focal and subclinical lesions confined to secondary lobules are thought to evolve into the serious lung pathology observed in EIPH cases through the effects of localised hypoxia induced by maximal exercise and partial airway obstruction. Once initiated, a vicious cycle of increasing inflammatory damage and further local bleeding is set in motion.
Publication Date: 1987-09-01 PubMed ID: 3678186DOI: 10.1111/j.2042-3306.1987.tb02636.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research analyzes clinical, post mortem, and imaging study results on exercise-induced pulmonary bleeding in 26 Thoroughbred racehorses. The study identifies bronchial artery angiogenesis, local hypoxia during intense exercise, and possible viral infection as potential factors contributing to these bleeding episodes, along with resulting secondary lung damage.
Methodology
- The study was conducted on 26 Thoroughbred racehorses, examining their post-mortem results, clinical records, and imaging studies.
- Various techniques such as coloured latex perfusions of pulmonary and bronchial circulations, routine gross, subgross, and histological examination, microradiography, and CT scans were used to assess the lungs’ condition.
Key Findings
- The main lesions found were multiple, separate and coalescing foci of moderately proliferative small airway disease with heavy neovascularisation of the bronchial circulation.
- The bronchial artery angiogenesis led to the dominance of systemic circulation in the air exchange structures within the affected areas. This resulted in an apparent left to right shunt.
- There were extensive regions of sequestered haemosiderophages observed, which signified past haemorrhage from blood vessels likely supplied by the bronchial arteries.
- Secondary damage including diffuse and focal tissue destruction and connective tissue reactions occurred due to localized bleeding and subsequent damage induced by macrophages.
Contributing Factors and Consequences
- The cause of the exercise-induced pulmonary haemorrhage (EIPH) was not directly determined, but the small airway-focused lesions suggest that low-grade bronchiolitis, potentially of viral origin, played a role.
- Gravitational effects also seemed to contribute to the dorsal distribution of the lesions.
- The mild and subclinical lesions, typically localized to secondary lobules, could evolve into more severe lung pathology, as seen in EIPH cases. This is believed to be resulting from local hypoxia triggered by strenuous exercise and partial airway obstruction.
- A self-sustaining damaging cycle of increasing inflammatory damage and further localized bleeding is triggered once the process begins.
Cite This Article
APA
O'Callaghan MW, Pascoe JR, Tyler WS, Mason DK.
(1987).
Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. VIII. Conclusions and implications.
Equine Vet J, 19(5), 428-434.
https://doi.org/10.1111/j.2042-3306.1987.tb02636.x Publication
Researcher Affiliations
- Department of Radiological Sciences, School of Veterinary Medicine, University of California, Davis 95616.
MeSH Terms
- Animals
- Bronchial Arteries / pathology
- Bronchiolitis / complications
- Bronchiolitis / veterinary
- Hemorrhage / etiology
- Hemorrhage / pathology
- Hemorrhage / veterinary
- Horse Diseases / etiology
- Horse Diseases / pathology
- Horses
- Hypoxia / complications
- Hypoxia / veterinary
- Lung / pathology
- Lung Diseases / etiology
- Lung Diseases / pathology
- Lung Diseases / veterinary
- Physical Exertion
Citations
This article has been cited 2 times.- Tunstall Pedoe D. Heart or lung failure: what causes exertional, high altitude, and cold immersion pulmonary oedema?. Br J Sports Med 1995 Dec;29(4):218-20.
- Johnstone IB, Viel L, Crane S, Whiting T. Hemostatic studies in racing standardbred horses with exercise-induced pulmonary hemorrhage. Hemostatic parameters at rest and after moderate exercise. Can J Vet Res 1991 Apr;55(2):101-6.
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