Pathophysiology of airway obstruction in horses: a review.
Abstract: Obstruction of the upper and lower airways is common in horses. In the upper airway, paresis of abductor muscles of the nares and larynx allows inspiratory collapse of soft tissues, which is accentuated by factors increasing upper airway resistance and by high inspiratory flow rates. Intrapulmonary airway obstruction occurs due to accumulation of secretions, release of chemical mediators in response to a variety of stimuli, and parasympathetic stimulation of airways. Obstruction of large airways increases the work of breathing, whereas obstruction of small airways may cause no measurable increase in resistance but does cause uneven distribution of ventilation and hypoxemia, especially during exercise. Poor collateral ventilation accentuates gas exchange problems in the horse with airway obstruction and may be a factor causing intrapulmonary hemorrhage during racing.
Publication Date: 1978-02-01 PubMed ID: 621177
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- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This research article explores the common issue of airway obstruction in horses, discussing the various causes and effects of such obstructions in both the upper and lower airways. The study particularly focuses on problems arising from exercise, and suggests a link between obstruction and intrapulmonary hemorrhage during racing.
Causes of Airway Obstruction
- The study first discusses the obstruction of upper airways, which often occurs due to paresis, a condition of muscular weakness, of abductor muscles in the nares (nostrils) and larynx (voice box). This condition can lead to the inspiratory collapse of soft tissues.
- The research denotes that this type of obstruction is worsened by factors that increase upper airway resistance, and by high inspiratory flow rates, which often occur during strenuous activities, such as exercising or racing.
- The obstruction of intrapulmonary (within the lungs) airways is another area of focus in the article, caused by the accumulation of secretions, the release of chemical mediators in response to various stimuli, and parasympathetic (part of the nervous system that serves to slow the heart rate, increase intestinal and glandular activity, and relax the sphincter muscles) stimulation of airways.
Effects of Airway Obstruction
- Obstructions within the large airways increase the work of breathing. This means they require the horse to use more energy and effort to intake and exhale air, which can negatively affect the horse’s overall wellness and performance.
- On the other hand, small airway obstructions do not necessarily result in a measurable increase in resistance. However, they do cause an uneven distribution of ventilation, leading to low levels of oxygen in blood (hypoxemia) – an issue that becomes particularly problematic during exercise.
- The study suggests a potential link between poor collateral ventilation, which aggravates gas exchange problems in horses with airway obstruction, and intrapulmonary hemorrhage (bleeding within the lungs) during racing. This implies that airway obstructions might result in serious health risks for horses, particularly those used in racing.
Cite This Article
APA
Robinson NE, Sorenson PR.
(1978).
Pathophysiology of airway obstruction in horses: a review.
J Am Vet Med Assoc, 172(3), 299-303.
Publication
Researcher Affiliations
MeSH Terms
- Airway Obstruction / etiology
- Airway Obstruction / immunology
- Airway Obstruction / physiopathology
- Airway Obstruction / veterinary
- Airway Resistance
- Animals
- Bronchi / immunology
- Bronchi / physiopathology
- Hemorrhage / etiology
- Hemorrhage / veterinary
- Horse Diseases / etiology
- Horse Diseases / physiopathology
- Horses
- Humans
- Larynx / physiopathology
- Lung / physiopathology
- Lung Diseases / etiology
- Lung Diseases / veterinary
- Nose / physiopathology
- Physical Exertion
- Respiration
- Respiratory Tract Infections / physiopathology
- Respiratory Tract Infections / veterinary
Citations
This article has been cited 6 times.- Go LM, Barton AK, Ohnesorge B. Pharyngeal diameter in various head and neck positions during exercise in sport horses. BMC Vet Res 2014 May 23;10:117.
- Choi HK, Finkbeiner WE, Widdicombe JH. A comparative study of mammalian tracheal mucous glands. J Anat 2000 Oct;197 Pt 3(Pt 3):361-72.
- Greenfield CL, Alsup JC, Hungerford LL, McKiernan BC. Bilateral recurrent laryngeal neurectomy as a model for the study of idiopathic canine laryngeal paralysis. Can Vet J 1997 Mar;38(3):163-7.
- Hanna J, Eyre P. Relaxant effects of selected bronchodilators on equine pulmonary vein and tracheal smooth muscle. Lung 1980;158(1):33-40.
- Bakima M, Baudet HM, Lekeux P, Lomba F. Respiratory and pulmonary haemodynamic changes during experimental organophosphate poisoning in goats. Vet Res Commun 1989;13(2):127-33.
- Doucet MY, Vrins AA, Ford-Hutchinson AW. Histamine inhalation challenge in normal horses and in horses with small airway disease. Can J Vet Res 1991 Jul;55(3):285-93.
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