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Hypothesis and Theory ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Physiol. | doi: 10.3389/fphys.2019.01333

Exercise Induced Laryngeal Obstruction in Humans and Equines. A Comparative Review.

 Zoe L. Fretheim-kelly1, 2*,  THOMAS HALVORSEN2, 3,  Hege Clemm4, Ola Roksund4, 5, John-Helge Heimdal2, 6, Maria Vollsæter4, 7, Constanze Fintl1 and  Eric Strand1
  • 1Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Norway
  • 2Department of Clinical Science, Faculty of Medicine, University of Bergen, Norway
  • 3Department of Sports Medicine, Norwegian School of Sport Sciences, Norway
  • 4Departement of Pediatrics, Haukeland University Hospital, Norway
  • 5Faculty of Health and Social Sciences, Western Norway University of Applied Sciences, Norway
  • 6Department of Oral Surgery, Haukeland University Hospital, Norway
  • 7Department of Clinical Sciences, University of Bergen, Norway

Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac disease and lack of fitness are the major differentials in both species. Laryngoscopic examination during exercise should be performed from rest to peak exertion to allow for a comprehensive diagnosis, including where the airway collapse begins, and thereafter how it progresses. Dynamic disorders with most visual similarity between humans and equines are: aryepiglottic fold collapse (both species); equine dynamic laryngeal collapse relative to some forms of human combined supraglottic/glottic collapse; and epiglottic retroversion (both species).
Quantitative grading techniques, such as airway pressure measurement, that have proven effective in veterinary research are currently being piloted in human studies. Conditions that appear visually similar are treated in comparable ways. The similarities of anatomy and certain types of dynamic collapse would suggest that the equine larynx provides a good model for human upper respiratory tract obstruction during exercise. Thus, close collaboration between veterinarians and medical personal may lead to further advancements in understanding pathophysiologic processes, and enhance the development of improved diagnostic tests and treatments that will benefit both species.

Keywords: comparative medicine, Exercise induced laryngeal obstruction (EILO), Exercise larynoscopy , Exercise dyspnoea, Larynx, Equine upper airway disorders, Dynamic laryngeal collapse

Received: 06 May 2019; Accepted: 07 Oct 2019.

Copyright: © 2019 Fretheim-kelly, HALVORSEN, Clemm, Roksund, Heimdal, Vollsæter, Fintl and Strand. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Zoe L. Fretheim-kelly, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, 0102, Oslo, Norway,