Arytenoid cartilage movement in resting and exercising horses.
Abstract: Endoscopic examinations of the larynx were recorded on 49 horses at rest and while exercising on a 5% inclined high-speed treadmill for 8 minutes at a maximum speed of 8.5 m/sec. Subjective laryngeal function scores at rest and while exercising were based on the degree and synchrony of arytenoid abduction. Arytenoid abduction was expressed as a left:right ratio of rima glottidis measurements. Horses with arytenoid cartilage asynchrony at rest (grade 2) could not be distinguished from normal horses (grade 1) when exercising because full abduction was maintained throughout the exercise period. Five horses with incomplete left arytenoid abduction at rest (grade 3) maintained full abduction during exercise; one grade 3 horse had dynamic collapse of the left side of the larynx. All horses with laryngeal hemiplegia at rest (grade 4) had dynamic collapse of the left side of the larynx during exercise. Forty-two horses with a resting left:right arytenoid abduction ratio greater than or equal to .71 consistently had complete arytenoid abduction at exercise. Seven horses with a left:right ratio less than .71 consistently showed dynamic collapse at exercise. There was no significant difference in the exercising left:right ratio between normal horses (grade 1) and grade 2 or grade 3 horses. These results suggest that horses with arytenoid asynchrony at rest do not suffer progressive collapse of the rima glottidis during exercise, and that incomplete arytenoid abduction at rest is an unreliable predictor of such collapse. Surgical treatment of all grade 2 horses and some grade 3 horses may be inappropriate.
Publication Date: 1991-03-01 PubMed ID: 2042281DOI: 10.1111/j.1532-950x.1991.tb00319.xGoogle Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research examines the movement of the arytenoid cartilage in horses both at rest and while exercising and finds that horses with arytenoid asynchrony at rest do not exhibit any progressive collapse of this cartilage during exercise, thus questioning the need for surgical intervention in certain cases.
Methodology
- The study was conducted on 49 horses where endoscopic examinations of their larynx were carried out both while they were at rest and while exercising.
- The exercise involved running on a 5% inclined high-speed treadmill for 8 minutes at a maximum speed of 8.5 m/sec.
Laryngeal Function Scores
- The horses were subjected to laryngeal function scores at rest and while exercising. This was based on the degree and synchrony of arytenoid abduction.
- The arytenoid abduction refers to the movement of the arytenoid cartilages located in the larynx that control the opening and closing of the larynx during breathing and noise production.
- The abduction was expressed as a left:right ratio of measurements of the rima glottidis, the opening between the vocal cords.
Findings
- Horses with arytenoid cartilage asynchrony at rest, defined as grade 2, could not be differentiated from normal horses when exercising as they maintained full abduction.
- Out of six horses with incomplete left arytenoid abduction at rest, defined as grade 3, five maintained full abduction during exercise, with one developing a dynamic collapse of the left side of the larynx.
- All horses with laryngeal hemiplegia at rest, that is, paralysis of one side of the larynx, defined as grade 4, developed dynamic collapse of the left side of their larynx during exercise.
- Horses with a resting left:right arytenoid abduction ratio greater than or equal to .71 consistently had complete arytenoid abduction at exercise. Seven horses with a left:right ratio less than .71 consistently showed dynamic collapse at exercise.
Implications of the Research
- The research suggests that horses with arytenoid asynchrony at rest do not suffer progressive collapse of the rima glottidis during exercise. Therefore, incomplete arytenoid abduction at rest is an unreliable predictor of such collapse.
- Furthermore, the results question the need for surgical treatment for all grade 2 horses and some grade 3 horses, which may otherwise be considered.
Cite This Article
APA
Rakestraw PC, Hackett RP, Ducharme NG, Nielan GJ, Erb HN.
(1991).
Arytenoid cartilage movement in resting and exercising horses.
Vet Surg, 20(2), 122-127.
https://doi.org/10.1111/j.1532-950x.1991.tb00319.x Publication
Researcher Affiliations
- Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
MeSH Terms
- Animals
- Arytenoid Cartilage / physiology
- Female
- Heart Rate
- Horses / anatomy & histology
- Horses / physiology
- Male
- Mandible / anatomy & histology
- Movement
- Physical Exertion / physiology
Citations
This article has been cited 8 times.- Lean NE, Bertin FR, Ahern BJ. Influence of unilateral and bilateral vocal cordectomy on airflow across cadaveric equine larynges at different Rakestraw grades of arytenoid abduction. Vet Surg 2022 Aug;51(6):974-981.
- Ahern BJ, Sole A, de Klerk K, Hogg LR, Vallance SA, Bertin FR, Franklin SH. Evaluation of postsale endoscopy as a predictor of future racing performance in an Australian thoroughbred yearling population. Aust Vet J 2022 Jun;100(6):254-260.
- Miller SM. Endoscopic recurrent laryngeal neuropathy grade prevalence in a sample of thoroughbred yearlings at public auction in South Africa (2013-2019). J S Afr Vet Assoc 2020 Apr 20;91(0):e1-e5.
- Ivester KM, Couëtil LL, Moore GE. An observational study of environmental exposures, airway cytology, and performance in racing thoroughbreds. J Vet Intern Med 2018 Sep;32(5):1754-1762.
- Okamoto I, Tokashiki R, Hiramatsu H, Motohashi R, Suzuki M. Detection of passive movement of the arytenoid cartilage in unilateral vocal-fold paralysis by laryngoscopic observation: useful diagnostic findings. Eur Arch Otorhinolaryngol 2012 Feb;269(2):565-70.
- Cheetham J, Regner A, Jarvis JC, Priest D, Sanders I, Soderholm LV, Mitchell LM, Ducharme NG. Functional electrical stimulation of intrinsic laryngeal muscles under varying loads in exercising horses. PLoS One 2011;6(8):e24258.
- Rhee HS, Steel CM, Derksen FJ, Robinson NE, Hoh JF. Immunohistochemical analysis of laryngeal muscles in normal horses and horses with subclinical recurrent laryngeal neuropathy. J Histochem Cytochem 2009 Aug;57(8):787-800.
- Murray RC, Gaughan EM. Pulsion diverticulum of the cranial cervical esophagus in a horse. Can Vet J 1993 Jun;34(6):365-7.
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