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Results of upper airway radiography and ultrasonography predict dynamic laryngeal collapse in affected horses.
Abstract: The pathogenesis of dynamic bilateral laryngeal collapse (DLC) associated with poll flexion is unknown. Diagnosis is dependent upon exercise endoscopy while replicating the flexed head position harness racehorses experience during racing. Objective: To describe the effects of poll flexion on rostrocaudal laryngeal positioning and laryngeal lumen width in resting horses diagnosed with DLC compared to controls, and to establish diagnostic criteria for DLC by use of diagnostic imaging. Methods: Case-control study. Methods: Fifty harness racehorses were prospectively included in the study: 25 cases diagnosed with DLC by treadmill endoscopy and 25 controls in which treadmill endoscopy revealed no abnormal findings. Laryngeal radiography and ultrasonography were obtained in neutral and flexed head positions. Laryngeal positioning and laryngohyoid conformation were compared between the groups and head positions. Results: Poll flexion induced a greater rostral advancement of the larynx in relation to the hyoid apparatus in resting harness racehorses affected with DLC compared to controls (P = 0.007). At the level of the vocal folds, poll flexion resulted in a smaller laryngeal lumen width in horses affected with DLC compared to controls (P = 0.04). Horses were significantly more likely to be affected with DLC when the thyrohyoid bone to thyroid cartilage distance was ≥12 mm in poll flexion (odds ratio 21.3, 95% confidence interval 3.65-124.8, P = 0.004) and when laryngeal lumen width at the level of the vocal folds was less in poll flexion than in the neutral head position (odds ratio 8.4; 95% confidence interval 1.6-44.1, P = 0.012). Conclusions: In DLC horses, poll flexion advanced the larynx more rostrally and resulted in a decreased airway lumen width compared to control horses. Laryngeal ultrasound and radiography may facilitate the diagnosis of DLC at rest.
© 2013 EVJ Ltd.
Publication Date: 2013-05-23 PubMed ID: 23662675DOI: 10.1111/evj.12066Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigated how the position of a horse’s head affects the larynx and breathing in horses diagnosed with dynamic bilateral laryngeal collapse (DLC), a condition that can affect performance in harness racing. Diagnostic imaging techniques, including radiography and ultrasound, were used to explore the condition and possibly establish a new diagnostic approach for restful horses.
Research Objective and Methodology
- The main objective of this research was to determine differences in laryngeal positioning and airway size between healthy horses and those diagnosed with DLC under varying head positions. The researchers hoped to establish diagnostic criteria for DLC using imaging technologies.
- The study involved a sample of 50 horses; 25 cases were diagnosed with DLC, while the remaining 25 served as controls with no recorded abnormalities.
- Diagnostic imaging, employing laryngeal radiography and ultrasonography, was utilised under both neutral and flexed head positions for all participating horses.
Results of the Study
- Upon flexing the head (poll flexion), horses with DLC demonstrated much more forward movement of the larynx as related to the hyoid bone when compared to unaffected animals.
- Measured at the level of the vocal folds, the width of the opening of the larynx (laryngeal lumen), shrinks significantly for the horses diagnosed with DLC during poll flexion.
- In poll flexion, a correlation was found linking a longer thyrohyoid bone to thyroid cartilage distance of ≥12 mm and DLC diagnosis. Here, the risk was multiplied by a factor of 21.3.
- When the width of laryngeal lumen was smaller during poll flexion than in neutral position, the odds of having DLC increased by a factor of 8.4.
Conclusions
- The researchers found that horses with DLC experienced a more forward movement of the larynx and a smaller airway when their heads were flexed, compared with horses not diagnosed with the condition.
- The study indicates that ultrasound and radiography could potentially be effective diagnostic tools to identify DLC, even when horses are at rest.
Cite This Article
APA
Fjordbakk CT, Chalmers HJ, Holcombe SJ, Strand E.
(2013).
Results of upper airway radiography and ultrasonography predict dynamic laryngeal collapse in affected horses.
Equine Vet J, 45(6), 705-710.
https://doi.org/10.1111/evj.12066 Publication
Researcher Affiliations
- Department of Companion Animal Clinical Sciences, Equine Teaching Hospital, Norwegian School of Veterinary Science, Norway.
MeSH Terms
- Animals
- Horse Diseases / diagnosis
- Horse Diseases / diagnostic imaging
- Horses
- Laryngeal Diseases / veterinary
- Nasopharynx / diagnostic imaging
- Radiography
- Ultrasonography
Citations
This article has been cited 3 times.- 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).
- Fretheim-Kelly ZL, Halvorsen T, Clemm H, Roksund O, Heimdal JH, Vollsæter M, Fintl C, Strand E. Exercise Induced Laryngeal Obstruction in Humans and Equines. A Comparative Review. Front Physiol 2019;10:1333.
- König von Borstel U, Kienapfel K, McLean A, Wilkins C, McGreevy P. Hyperflexing the horse's neck: a systematic review and meta-analysis. Sci Rep 2024 Oct 2;14(1):22886.
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