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Equine veterinary journal2020; 53(1); 44-50; doi: 10.1111/evj.13287

A bitless bridle does not limit or prevent dynamic laryngeal collapse.

Abstract: Bits have often been incriminated as a cause of upper respiratory tract obstruction in horses; however, no scientific studies are available to confirm or refute these allegations. Clinical signs of dynamic laryngeal collapse associated with poll flexion (DLC) are induced when susceptible horses are ridden or driven into the bit. Objective: To determine whether use of Dr Cook's™ Bitless Bridle, instead of a conventional snaffle bit bridle, would reduce the severity of DLC in affected horses measured objectively using inspiratory tracheal pressures. Methods: Intervention study using each horse as its own control in a block randomised order. Methods: Nine Norwegian Swedish Coldblooded trotters previously diagnosed with DLC were exercised on two consecutive days using a standardised high-speed treadmill protocol with either a conventional bridle with a snaffle bit, or Dr Cook's™ Bitless Bridle. Head and neck position, rein tension, inspiratory tracheal pressure measurements, and laryngeal videoendoscopy recordings were obtained. A heart rate greater than 200 bpm, and similar degrees of poll flexion/head height, had to be achieved in both bridles for the individual horse's data to be included for comparison. Results: Seven horses' data met the inclusion criteria. The change in mean inspiratory tracheal pressure between free and flexion phases in the bitless bridle (-15.2 ± 12.3 cmH2 O) was significantly greater (P < .001) than in the snaffle bit bridle (-9.8 ± 7.9 cmH2 O). Mean inspiratory pressure during the free phase was significantly (P < .001) more negative with the snaffle bit bridle (-32.3 ± 6.3 cmH2 O), vs the bitless bridle (-28.5 ± 6.9 cmH2 O). Mean pressures in flexion phase, snaffle bridle (-42.1 ± 10.8 cmH2 O), vs bitless bridle (-43.7 ± 15.6 cmH2 O) where not significantly different between bridles (P = .2). Conclusions: Small sample size due to difficulty recruiting suitable clinical cases. Conclusions: This study could not provide any clear evidence that the effect of a snaffle bit in a horse's mouth influences the development or severity of DLC. Instead, head and neck angles induced by rein tension seem to be the key event in provoking DLC in susceptible horses.
© 2020 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2020-06-17 PubMed ID: 32449540DOI: 10.1111/evj.13287Google 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.

The research investigates whether Dr. Cook’s Bitless Bridle, compared to a conventional snaffle bit bridle, would decrease the severity of dynamic laryngeal collapse in horses. The study found no clear evidence that the use of a snaffle bit influences the development or severity of this condition, suggesting that the angle of the horse’s head and neck induced by rein tension may play a more significant role.

Objective and Methods

  • The main goal of this study was to determine if using Dr. Cook’s Bitless Bridle could reduce the severity of dynamic laryngeal collapse (DLC) in horses. The hypothesis was based on the common speculation that bits could cause upper respiratory tract obstruction in horses.
  • The researchers used an intervention study design where every horse served as its own control. Nine horses from Norwegian Swedish Coldblooded trotters, all previously diagnosed with DLC, were exercised on two consecutive days. In each session, they used either a conventional bridle with a snaffle bit, or Dr Cook’s Bitless Bridle.
  • To ensure accuracy and consistency in monitoring, the researchers ensured that every horse had to achieve a heart rate greater than 200 bpm and similar degrees of poll flexion/head height in both bridles for their data to be included in the comparison.
  • The researchers measured head and neck position, rein tension, inspiratory tracheal pressure, and recorded a laryngeal videoendoscopy. These measurements helped them objectively evaluate the severity of DLC in the horses.

Results

  • The criteria for inclusion was met by seven horses’ data. The researchers noted a greater change in mean inspiratory tracheal pressure in the bitless bridle than in the snaffle bit bridle when comparing their free and flexion phases. Furthermore, mean inspiratory pressure during the free phase was more negative with the snaffle bit bridle. However, they found no significant differences between the two bridles during the flexion phase.
  • Despite the greater difference in inspiratory pressure change with the bitless bridle, the study could not provide clear evidence that a snaffle bit in a horse’s mouth influences the development or severity of DLC.

Conclusions

  • Due to the difficulty of recruiting suitable clinical cases, the study had a small sample size, which might limit the strength of its conclusions.
  • The results suggested that head and neck angles induced by rein tension seem to be the key factor in provoking DLC in susceptible horses rather than the use of a snaffle bit. This emphasis on angulation and tension could contribute to new training methods and potential ways to manage or reduce the severity of DLC in horses.

Cite This Article

APA
Fretheim-Kelly Z, Fjordbakk CT, Fintl C, Krontveit R, Strand E. (2020). A bitless bridle does not limit or prevent dynamic laryngeal collapse. Equine Vet J, 53(1), 44-50. https://doi.org/10.1111/evj.13287

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 1
Pages: 44-50

Researcher Affiliations

Fretheim-Kelly, Zoe
  • Faculty of Veterinary Medicine, Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway.
  • Haukeland University Hospital, Bergen, Norway.
Fjordbakk, Cathrine T
  • Faculty of Veterinary Medicine, Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway.
Fintl, Constanze
  • Faculty of Veterinary Medicine, Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway.
Krontveit, Randi
  • Norwegian Medicines Agency, Oslo, Norway.
Strand, Eric
  • Faculty of Veterinary Medicine, Companion Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway.

MeSH Terms

  • Airway Obstruction / veterinary
  • Animals
  • Horse Diseases / prevention & control
  • Horses
  • Larynx
  • Norway
  • Sweden

Grant Funding

  • Faculty of Veterinary Science, Norwegian University of Life Sciences

References

This article includes 28 references
  1. Martin BB Jr, Reef VB, Parente EJ, Sage AD. Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996).. J Am Vet Med Assoc 2000;216:554-8.
  2. Davidson EJ, Harris M, Martin BB, Nolen-Walston R, Boston RC, Reef V. Exercising blood gas analysis, dynamic upper respiratory tract obstruction, and postexercising bronchoalveolar lavage cytology-a comparative study in poor performing horses.. J Equine Vet Sci 2011;31:475-80.
  3. 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;38:393-9.
  4. Wilsher S, Allen WR, Wood JL. Factors associated with failure of thoroughbred horses to train and race.. Equine Vet J 2006;38:113-8.
  5. Cook WR. Bit-induced asphyxia in the horse.. J Equine Vet Sci 2002;22:7-14.
  6. Cook WR. Bit-induced asphyxia in the racehorse as a cause of sudden death.. Equine Vet Educ 2016;28:405-9.
  7. Mellor DJ, Beausoleil NJ. Equine welfare during exercise: an evaluation of breathing, breathlessness and bridles.. Animals 2017;7:41.
  8. Strand E, Hanche-Olsen S, Grønvold AMR, Mellum CN. Dynamic bilateral arytenoid and vocal fold collapse associated with head flexion in 5 Norwegian Coldblooded Trotter racehorses.. Equine Vet Educ 2004;16:242-50.
  9. Strand E, Fjordbakk CT, Holcombe SJ, Risberg A, Chalmers HJ. Effect of poll flexion and dynamic laryngeal collapse on tracheal pressure in Norwegian Coldblooded Trotter racehorses.. Equine Vet J 2009;41:59-64.
  10. Strand E, Fjordbakk CT, Sundberg K, Spangen L, Lunde H, Hanche-Olsen S. Relative prevalence of upper respiratory tract obstructive disorders in two breeds of harness racehorses (185 cases: 1998-2006).. Equine Vet J 2012;44:518-23.
  11. McCarrel TM, Woodie JB. Update on laryngeal disorders and treatment.. Vet Clin North Am Equine Pract 2015;31:13-26.
  12. Hanche-Olsen S, Rannem L, Strand E. Bilateral dynamic laryngeal collapse associated with collection in “high poll flexion” in a gaited Icelandic horse.. Pferdeheilkunde 2010;26:810-3.
  13. Clayton HM, Lee R. A fluoroscopic study of the position and action of the jointed snaffle bit in the horse's mouth.. J Equine Vet Sci 1984;4:193-6.
  14. Edwards EH. The Complete Book of Bits & Bitting.. .
  15. Houghton-Brown J, Pilliner S, Davies Z. Horse and Stable Management, 4th edn.. .
  16. Fjordbakk CT, Holcombe S, Fintl C, Chalmers H, Strand E. A novel treatment for dynamic laryngeal collapse associated with poll flexion: the modified checkrein.. Equine Vet J 2012;44:207-13.
  17. Fjordbakk CT, Strand E, Hanche-Olsen S. Surgical and conservative management of bilateral dynamic laryngeal collapse associated with poll flexion in harness race horses.. Vet Surg 2008;37:501-7.
  18. Fjordbakk CT, Chalmers HJ, Holcombe SJ, Strand E. Results of upper airway radiography and ultrasonography predict dynamic laryngeal collapse in affected horses.. Equine Vet J 2013;45:705-10.
  19. Strand E, Skjerve E. Complex dynamic upper airway collapse: associations between abnormalities in 99 harness racehorses with one or more dynamic disorders.. Equine Vet J 2012;44:524-8.
  20. Franklin SH, Naylor JR, Lane JG. Videoendoscopic evaluation of the upper respiratory tract in 93 sport horses during exercise testing on a high-speed treadmill.. Equine Vet J 2006;38(S36):540-5.
  21. Allen KJ, Terron-Canedo N, Hillyer MH, Franklin SH. Equitation and exercise factors affecting dynamic upper respiratory tract function: a review illustrated by case reports.. Equine Vet Educ 2011;23:361-8.
  22. Woodie JB, Ducharme NG, Hackett RP, Erb HN, Mitchell LM, Soderholm LV. Can an external device prevent dorsal displacement of the soft palate during strenuous exercise?. Equine Vet J 2005;37:425-9.
  23. Singh B. Dyce, Sack, and Wensing's Textbook of Veterinary Anatomy, 5th edn.. .
  24. Chalmers HJ, Farberman A, Bermingham A, Sears W, Viel L. The use of a tongue tie alters laryngohyoid position in the standing horse.. Equine Vet J 2013;45:711-4.
  25. Fregosi RF, Fuller DD. Respiratory-related control of extrinsic tongue muscle activity.. Respir Physiol 1997;110:295-306.
  26. Van de Graaff WB, Gottfried SB, Mitra J, van Lunteren E, Cherniack NS, Strohl KP. Respiratory function of hyoid muscles and hyoid arch.. J Appl Physiol Respir Environ Exerc Physiol 1984;57:197-204.
  27. Holcombe SJ, Ducharme NG. Upper airway function of normal horses during exercise.. In: Hinchcliff KW, Geor RJ, Kaneps AJ, editors. Equine Exercise Physiology: The Science of Exercise in the Athletic Horse. 1st edn. Philiadelphia: Saunders/Elsevier, 2008; p. 170-92.
  28. Cook WR. A hypothetical, aetiological relationship between the horse's bit, nasopharyngeal asphyxia and negative pressure pulmonary oedema.. Equine Vet Educ 2014;26:381-9.

Citations

This article has been cited 1 times.
  1. Tilley P, Simões J, Sales Luis JP. Effects of a 15° Variation in Poll Flexion during Riding on the Respiratory Systems and Behaviour of High-Level Dressage and Show-Jumping Horses. Animals (Basel) 2023 May 22;13(10).
    doi: 10.3390/ani13101714pubmed: 37238147google scholar: lookup
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