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PloS one2019; 14(10); e0224524; doi: 10.1371/journal.pone.0224524

Investigation into pathophysiology of naturally occurring palatal instability and intermittent dorsal displacement of the soft palate (DDSP) in racehorses: Thyro-hyoid muscles fatigue during exercise.

Abstract: Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nine racehorses, and connected to a telemetric unit for electromyographic monitoring implanted subcutaneously. The horses were recruited based on upper airway function evaluated through wireless endoscopy during exercise. Five horses, with normal function, were used as control; four horses were diagnosed as DDSP-affected horses based on repeated episodes of intermittent dorsal displacement of the soft palate. The electromyographic activity of the thyro-hyoid muscles recorded during incremental exercise tests on a high-speed treadmill was analyzed to measure the mean electrical activity and the median frequency of the power spectrum, thereafter subjected to wavelet decomposition. The affected horses had palatal instability with displacement on repeated exams prior to surgical implantation. Although palatal instability persisted after surgery, only two of these horses displaced the palate after instrumentation. The electromyographic traces from this group of four horses showed, at highest exercise intensity, a decrease in mean electrical activity and median power frequency, with progressive decrease in the contribution of the high frequency wavelets, consistent with development of thyro-hyoid muscle fatigue. The results of this study identified fatigue as the main factor leading to exercise induced palatal instability and DDSP in a group of racehorses. Further studies are required to evaluate the fiber type composition and metabolic characteristics of the thyro-hyoid muscles that could predispose to fatigue.
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Publication Date: 2019-10-25 PubMed ID: 31652282PubMed Central: PMC6814218DOI: 10.1371/journal.pone.0224524Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates the physical issue of intermittent dorsal displacement of the soft palate (DDSP) in racehorses, which often leads to poor performance due to airway obstruction. By focusing on the thyro-hyoid muscles, the researchers identified muscle fatigue as a key factor leading to this problem.

Objective and Study Setup

  • The main objective of this study is to delve into the pathophysiology of DDSP in racehorses. DDSP is a condition where the horse’s soft palate partially blocks the airway during high-intensity physical activity, leading to performance issues. The researchers aim to explore the role of the thyro-hyoid muscles in this condition by closely observing their responses during physical exercise.
  • A total of nine racehorses took part in the study. Electrodes were surgically implanted into their thyro-hyoid muscles, and their muscle activity was recorded using a subcutaneously implanted telemetric unit.
  • For study purposes, the horses were divided into two groups: a control group of five horses that displayed normal upper airway function based on wireless endoscopy, and a DDSP group made up of four horses that had shown repeated instances of the soft palate issue.

Observations and Results

  • The electromyographic activity of the thyro-hyoid muscles in the horses was recorded during various high-speed treadmill exercises. Two primary aspects were measured: the mean electrical activity and the median frequency of the power spectrum. This data was then subjected to wavelet decomposition analysis.
  • In the group of horses diagnosed with DDSP, electromyographic traces revealed a decrease in mean electrical activity and median power frequency at the highest exercise intensity levels. This was accompanied by a progressive decrease in high frequency wavelets’ contribution, signifying muscle fatigue.
  • The persisting palatal instability, even after surgery and instrumentation, along with muscle activity changes, led researchers to pinpoint fatigue as the primary reason for exercise-induced DDSP in these horses. However, only two out of the four affected horses continued to experience soft palate displacement post surgical intervention.

Conclusions

  • The study’s findings indicate that fatigue in the thyro-hyoid muscles contributes significantly to DDSP in racehorses. This discovery aids in a better understanding of the physiological issues faced by racing horses.
  • Though muscle fatigue has been identified as a leading factor, questions regarding the fiber type composition and metabolic characteristics of the thyro-hyoid muscles persist. Future studies need to address these aspects, which could further uncover the predisposition to fatigue in these muscles and hence provide possible ways to improve racing horse performance by minimizing instances of DDSP.

Cite This Article

APA
Cercone M, Olsen E, Perkins JD, Cheetham J, Mitchell LM, Ducharme NG. (2019). Investigation into pathophysiology of naturally occurring palatal instability and intermittent dorsal displacement of the soft palate (DDSP) in racehorses: Thyro-hyoid muscles fatigue during exercise. PLoS One, 14(10), e0224524. https://doi.org/10.1371/journal.pone.0224524

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 14
Issue: 10
Pages: e0224524

Researcher Affiliations

Cercone, Marta
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
Olsen, Emil
  • Department of Clinical Sciences and Services, Royal Veterinary College, London, Hatfield, United Kingdom.
Perkins, Justin D
  • Department of Clinical Sciences and Services, Royal Veterinary College, London, Hatfield, United Kingdom.
Cheetham, Jonathan
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
Mitchell, Lisa M
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
Ducharme, Norm G
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.

MeSH Terms

  • Animals
  • Electromyography
  • Female
  • Horse Diseases / pathology
  • Horse Diseases / physiopathology
  • Horses
  • Male
  • Muscle Fatigue
  • Palate, Soft / pathology
  • Physical Conditioning, Animal
  • Signal Processing, Computer-Assisted
  • Thyroid Gland / physiopathology

Conflict of Interest Statement

This study was funded by the Grayson Jockey Club Research Foundation. The specialized equipment used in the study (intramuscular electrodes, EMG transmitters and recorders) was provided free of charges by a commercial source: Med-El Elektromedizinische Geräte GmbH, Innsbruck, Austria. No researchers’ salaries were provided related to this research. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

References

This article includes 59 references
  1. Poole DC, Erickson HH. Highly athletic terrestrial mammals: horses and dogs.. Compr. Physiol. 2011; 1: 1–37.
    doi: 10.1002/cphy.c091001pubmed: 23737162google scholar: lookup
  2. Barone R. Anatomie comparée del mammifères domestique: Tome 3, Splanchnologie I, Appareil digestif, Appareil respiratoire.. 4eme edition Ed: Baronne, VIGOT, Paris; 1996.
  3. Rehder RS, Ducharme NG, Hackett RP, Nielan GJ. Measurement of upper airway pressures in exercising horses with dorsal displacement of the soft palate.. Am J Vet Res. 1995; 56: 269–274.
    pubmed: 7771690
  4. Parente EJ, Martin BB, Tulleners EP, Ross MW. Dorsal Displacement of the Soft Palate in 92 Horses During High-Speed Treadmill Examination (1993–1998).. Vet Surg. 2002; 31: 507–512.
    pubmed: 12415518
  5. Lane JG, Bladon B, Little DR, Naylor JR, Franklin SH. Dynamic obstructions of the equine upper respiratory tract. Part 1: observations during high-speed treadmill endoscopy of 600 Thoroughbred racehorses.. Equine vet J. 2006; 38: 393–399.
    doi: 10.2746/042516406778400583pubmed: 16986598google scholar: lookup
  6. Franklin SH, Naylor JRJ, Lane JG. Videoendoscopic evaluation of the upper respiratory tract in 93 sport horses during exercise testing on a high-speed treadmiII.. Equine vet J. 2006; Suppl 36: 540–545.
    pubmed: 17402480
  7. Priest DT, Cheetham J, Regner AL, Mitchell L, Soderholm LV, Tamzali Y. Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races.. Equine vet J. 2012; 44: 529–534.
    doi: 10.1111/j.2042-3306.2012.00562.xpubmed: 22435542google scholar: lookup
  8. Holcombe SJ, Derksen FJ, Stick JA, Robinson NE. Effect of bilateral blockade of the pharyngeal branch of the vagus nerve on soft palate function in horses.. Am J Vet Res. 1998; 59: 504–508.
    pubmed: 9563638
  9. Cheetham J, Pigott JH, Hermanson JW, Campoy L, Soderholm LV, Thorson lM. Role of the hypoglossal nerve in equine nasopharyngeal stability.. J Appl Physiol. 2009; 107: 471–477.
    doi: 10.1152/japplphysiol.91177.2008pubmed: 19498094google scholar: lookup
  10. Ducharme NG, Hackett RP, Woodie JB, Dykes N, Erb HN, Mitchell LM. Investigations into the role of the thyrohyoid muscles in the pathogenesis of dorsal displacement of the soft palate in horses.. Equine vet J. 2003; 35: 258–263.
    doi: 10.2746/042516403776148200pubmed: 12755428google scholar: lookup
  11. Woodie JB, Ducharme NG, Kanter P, Hackett RP, Erb HN. Surgical advancement of the larynx (laryngeal tie-forward) as a treatment for dorsal displacement of the soft palate in horses: a prospective study 2001–2004.. Equine vet J. 2005; 37: 418–23.
    doi: 10.2746/042516405774480076pubmed: 16163943google scholar: lookup
  12. Sisson S. Equine myology. In: Sisson S, Grossman JD, Getty R, editors. The Anatomy of the Domestic A n i m a l s. W.B. Saunders Co., Philadelphia: 1975. pp 376–453.
  13. Hong KH, Ye M, Kim YM, Kevorkian KF, Berke GS. The role of strap muscles in phonation—in vivo canine laryngeal model.. J. Voice 1997; 11: 23–32.
    pubmed: 9075173
  14. Zantigh AJ, Ducharme NG, Mitchell LM, Cheetham J. Effects of hypoglossal nerve block and electrical stimulation of the thyrohyoideus muscles on position of the larynx and hyoid apparatus in healthy horses.. Am J Vet Res. 2013; 74: 784–9.
    doi: 10.2460/ajvr.74.5.784pubmed: 23627393google scholar: lookup
  15. Williams JM. Electromyography in the horse: A useful technology?. JEVS 2018; 60: 43–58.
  16. Solomonow M, Baten C, Smit J, Baratta R, Hermens H, D’Ambrosia R. Electromyogram power spectra frequencies associated with motor unit recruitment strategies.. J Appl Physiol 1990; 68: 1177–1185.
    doi: 10.1152/jappl.1990.68.3.1177pubmed: 2341343google scholar: lookup
  17. Kupa EJ, Roy SH, Kandaraian SC, De Luca CJ. Effects of muscle fiber type and size on EMG median frequency and conduction velocity.. J Appl Phys 1995; 79: 23–32.
    pubmed: 7559225
  18. Ament W, Bonga GJJ, Hof AL, Verkerke GJ. EMG Median Power Frequency in an Exhausting Exercise.. J Electromyogr Kinesiol. 1993; 3: 214–220.
    doi: 10.1016/1050-6411(93)90010-Tpubmed: 20870536google scholar: lookup
  19. Bilodeau M, Schindler-Ivens S, Williams DM, Chandran R, Sharma SS. EMG frequency content changes with increasing force and during fatigue in the quadriceps femoris muscle of men and women.. J Electromyogr Kinesiol. 2003; 13: 83–92.
    pubmed: 12488090
  20. Tessier C, Holcombe SJ, Stick JA, Derksen FJ, Boruta D. Electromyographic activity of the stylopharyngeus muscle in exercising horses.. Equine vet J. 2005; 37: 232–235.
    doi: 10.2746/0425164054530759pubmed: 15892232google scholar: lookup
  21. Holcombe SJ, Derksen FJ, Robinson NE. Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horses.. Equine vet J. 2007; 39: 451–455.
    doi: 10.2746/042516407x197752pubmed: 17910271google scholar: lookup
  22. Morello SL, Ducharme NG, Hackett RP, Warnick LD, Mitchell LM, Soderholm LV. Activity of selected rostral and caudal hyoid muscles in clinically normal horses during strenuous exercise.. Am J Vet Res. 2008; 69: 682–689.
    doi: 10.2460/ajvr.69.5.682pubmed: 18447802google scholar: lookup
  23. Gonzalez-Izal M, Malanda A, Gorostiaga E, Izquierdo M. Electromyographic models to assess muscle fatigue. Review.. J Electromyogr Kinesiol. 2012; 22: 501–512.
    doi: 10.1016/j.jelekin.2012.02.019pubmed: 22440555google scholar: lookup
  24. Rose RJ, Hendrickson DK, Knight PK. Clinical exercise testing in the normal thoroughbred racehorse.. Aust Vet J. 1990; 67: 345–348.
    doi: 10.1111/j.1751-0813.1990.tb07394.xpubmed: 2288536google scholar: lookup
  25. Nielan GJ, Rehder RS, Ducharme NG, Hackett RP. Measurement of tracheal static pressure in exercising horses.. Vet Surg. 1992; 21: 423–428.
    pubmed: 1455643
  26. Ducharme NG, Hackett RP, Ainsworth DM, Erb HN, Shannon KJ. Repeatability and normal values for measurement of pharyngeal and tracheal pressures in exercising horses.. Am J Vet Res. 1994; 55: 368–374.
    pubmed: 8192260
  27. Pigott JH, Ducharme NG, Mitchell LM, Soderholm LV, Cheetham J. Incidence of swallowing during exercise in horses with dorsal displacement of the soft palate.. Equine vet. J. 2010; 42(8): 732–737.
    doi: 10.1111/j.2042-3306.2010.00116.xpubmed: 21039804google scholar: lookup
  28. Kneisz L, Unger E, Lanmuller H, Mayr W. In Vitro Testing of an Implantable Wireless Telemetry System for Long-Term Electromyography Recordings in Large Animals.. Artif Organs. 2015; 39: 897–902.
    doi: 10.1111/aor.12626pubmed: 26471141google scholar: lookup
  29. Hodson-Tole EF, Wakeling JM. Motor unit recruitment patterns 1: responses to changes in locomotor velocity and incline.. J Exp Biol. 2008; 211: 1882–1892.
    doi: 10.1242/jeb.014407pubmed: 18515718google scholar: lookup
  30. von Tscharner V. Intensity analysis in time-frequency space of surface myoelectric signals by wavelets of specified resolution.. J Electromyogr Kinesiol. 2000; 10: 433–445.
    pubmed: 11102846
  31. Allen K, Franklin S. Characteristics of palatal instability in Thoroughbred racehorses and their association with the development of dorsal displacement of the soft palate.. Equine vet. J. 2013; 45(4): 454–459.
    doi: 10.1111/evj.12004pubmed: 23294046google scholar: lookup
  32. Allen K, Franklin S. The effect of palatal dysfunction on measures of ventilation and gas exchange in Thoroughbred racehorses during high intensity exercise.. Equine vet. J. 2013; 45(3): 350–354.
    doi: 10.1111/j.2042-3306.2012.00627.xpubmed: 22943460google scholar: lookup
  33. Moritani T, Muro M, Nagata A. Intramuscular and surface electromyogram changes during muscle fatigue.. J Appl Physiol. 1986; 60: 1179–85.
    doi: 10.1152/jappl.1986.60.4.1179pubmed: 3700300google scholar: lookup
  34. Linssen WHJP, Stegeman DF, Joosten EMG, van’t Hof MA, Binkhorst RA, Notermans SLH. Variability and interrelationships of surface EMG parameters during local muscle fatigue.. Muscle Nerve. 1993; 16: 849–856.
    doi: 10.1002/mus.880160808pubmed: 8332138google scholar: lookup
  35. Ainsworth DM, Eicker SW, Nalevanko ME, Ducharme NG, Hackett RP, Snedden K. The effect of exercise on diaphragmatic activation in horses.. Respir Physiol. 1996; 106: 135–46.
    pubmed: 8946575
  36. Adam A, De Luca CJ. Firing rates of motor units in human vastus lateralis muscle during fatiguing isometric contractions.. J Appl Physiol 2005; 99: 268–280.
    doi: 10.1152/japplphysiol.01344.2004pubmed: 16036904google scholar: lookup
  37. Chien M-Y, Chang Y-J, Lee P, Yang P-C, Wu Y-T. Electrophysiologic changes with incremental exercise in obstructive sleep apnea.. Muscle Nerve. 2013; 48: 212–218.
    doi: 10.1002/mus.23745pubmed: 23696472google scholar: lookup
  38. Seven YB, Mantilla CB, Zhan W-Z, Sieck GC. Non-stationarity and power spectral shifts in EMG activity reflect motor unit recruitment in rat diaphragm muscle.. Respir Physiol Neurobiol. 2013; 185: 400–409.
    doi: 10.1016/j.resp.2012.08.020pmc: PMC3529998pubmed: 22986086google scholar: lookup
  39. Karlsson S, Yu J, Akay M. Time-frequency analysis of myoelectric signals during dybamic contractions: a comparative study.. IEEE Trans Biomed Eng. 2000; 47(2): 228–238.
    doi: 10.1109/10.821766pubmed: 10721630google scholar: lookup
  40. Wakeling JM, Kaya M, Temple GK, Johnston IA, Herzog W. Determining patterns of motor recruitment during locomotion.. J Exp Biol. 2002; 205: 359–369.
    pubmed: 11854372
  41. Wakeling JM, Syme DA. Wave properties of action potentials from fast and slow motor units of rats.. Muscle Nerve. 2002; 26: 659–668.
    doi: 10.1002/mus.10263pubmed: 12402288google scholar: lookup
  42. Lee SSM, de Boef Miara M, Arnold AS, Biewener AA, Wakeling JM. EMG analysis tuned for determining the timing and level of activation in different motor units.. J Electromyogr Kinesiol. 2011; 21: 557–565.
    doi: 10.1016/j.jelekin.2011.04.003pmc: PMC3172164pubmed: 21570317google scholar: lookup
  43. Van de Graaff WB, Gottfried SB, Mitra J, van Lunteren E, Cherniack S, Strohl KP. Respiratory function of hyoid muscles and hyoid arch.. J Appl Physiol 1984; 57:197–204.
    doi: 10.1152/jappl.1984.57.1.197pubmed: 6469781google scholar: lookup
  44. Vilkman E, Sonninen A, Hurme P, Korkko P. External Laryngeal Frame Function in Voice Production Revisited: A Review.. J Voice. 1996; 10: 78–92.
    pubmed: 8653181
  45. Baker WHJ. High speed fluoroscopic evaluation of laryngopharyngeal movement during exercise in clinically normal horses and in horses effected with dorsal displacement of the soft palate.. M.Sc. Thesis, Royal Veterinary College 2013.
  46. Ducharme NG. Pharynx. In Auer JA, Stick JA, editors. Equine Surgery. 4th ed Elsevier, St. Louis, Missouri: 2012. pp 577–585.
  47. NHLBI Workshop summary. Respiratory muscle fatigue. Report of the Respiratory Muscle Fatigue Workshop Group.. Am Rev Respir Dis. 1990; 142: 474–80.
    doi: 10.1164/ajrccm/142.2.474pubmed: 2382912google scholar: lookup
  48. Gandevia SC. Spinal and Supraspinal Factors in Human Muscle Fatigue.. Physiol Rev. 2001; 81: 1725–1789.
    doi: 10.1152/physrev.2001.81.4.1725pubmed: 11581501google scholar: lookup
  49. Pette D. Metabolic heterogeneity of muscle fibers.. J Exp Biol. 1985; 115: 179–189.
    pubmed: 4031763
  50. Fitts RH. The cross-bridge cycle and skeletal muscle fatigue.. J Appl Physiol 2008; 104: 551–558.
    doi: 10.1152/japplphysiol.01200.2007pubmed: 18162480google scholar: lookup
  51. Qaisar R, Bhaskaran S, Van Remmen H. Muscle fiber type diversification during exercise and regeneration.. Free Radic Biol Med. 2016; 98: 56–67.
    doi: 10.1016/j.freeradbiomed.2016.03.025pubmed: 27032709google scholar: lookup
  52. Allen K, Franklin S. Comparisons of overground endoscopy and treadmill endoscopy in UK Thoroughbred racehorses.. Equine vet J. 2010; 42(3): 186–191.
    doi: 10.1111/j.2042-3306.2010.00033.xpubmed: 20486973google scholar: lookup
  53. Holcombe SJ, Ducharme NG. Pharynx. In Auer JA, Stick JA, editors. Equine Surgery. 2nd ed Elsevier, Philadelphia, Pennsylvania: 1999. pp 337–348.
  54. Barakzai SZ, Dixon PM. Conservative treatment for thoroughbred racehorses with intermittent dorsal displacement of the soft palate.. Vet Rec. 2005; 157(12): 337–340.
    doi: 10.1136/vr.157.12.337pubmed: 16170000google scholar: lookup
  55. Pollock PJ, Perkins J, Kelly P, Reardon R. Longitudinal overground endoscopy findings for conservative management of DDSP.. ECVS proceedings 2016 Available from: http://www.ivis.org/proceedings/ecvs/2016/170.
  56. McEntire SJ, Smith JR, Ferguson CS, Brown KR, Kurti SP, Harms CA. The effect of exercise training with an additional inspiratory load on inspiratory muscle fatigue and time-trial performance.. Respir Physiol Neurobiol. 2016; 230: 54–59.
    doi: 10.1016/j.resp.2016.05.001pubmed: 27195511google scholar: lookup
  57. Taylor AW, Bachman L. The effects of endurance training on muscle fibre types and enzyme activities.. Can J Appl Physiol. 1999; 24: 41–53.
    pubmed: 9916180
  58. Ramirez-Sarmiento A, Orozco-Levi M, Guell R, Barreiro E, Hernandez N, Mota S. Inspiratory muscle training in patients with chronic obstructive pulmonary disease: structural adaptation and physiologic outcomes.. Am J Respir Crit Care Med. 2002; 166: 1491–1497.
    doi: 10.1164/rccm.200202-075OCpubmed: 12406842google scholar: lookup
  59. Sales AT, Fregonezi GA, Ramsook AH, Guenette JA, Lima IN, Reid WD. Respiratory muscle endurance after training in athletes and non-athletes: A systematic review and meta-analysis.. Phys Ther Sport. 2016; 17: 76–86.
    doi: 10.1016/j.ptsp.2015.08.001pubmed: 26626464google scholar: lookup

Citations

This article has been cited 2 times.
  1. Mazan M. Equine exercise physiology-challenges to the respiratory system. Anim Front 2022 Jun;12(3):15-24.
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  2. Fitzharris LE, Hezzell MJ, McConnell AK, Allen KJ. Training the equine respiratory muscles: Inspiratory muscle strength. Equine Vet J 2023 Mar;55(2):306-314.
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