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Equine veterinary journal2025; doi: 10.1111/evj.14556

Objective diagnosis of alar fold collapse in active Standardbred trotting racehorses using nasopharyngeal airway pressure measurements.

Abstract: Clinical evaluation of alar fold (AF) collapse is presently based upon subjective evaluation of improvement in breathing and respiratory noise after suturing the AFs dorsally. Objective: To evaluate use of nasopharyngeal airway pressure (NAP) as an objective method of assessing for the presence of AF collapse during exercise. NAPs should also potentially provide a precise means to grade the degree of airway obstruction present and response to surgical treatment. Methods: Prospective clinical study of actively racing Standardbred horses. Methods: Standardbreds undergoing this test were outfitted with a heart rate monitor and warmed up on the treadmill for approximately 2000 m, prior to instrumentation with the analogue pressure sensor positioned in the nasopharynx. NAPs were measured continuously before and after the AFs were temporarily sutured dorsally, when horses were trotted at a heart rate ≥200 bpm for 2 min under identical testing circumstances. Peak inspiratory and expiratory NAPs were determined for each horse. A two-way repeated measures ANOVA was performed to analyse the effect of suturing the AFs dorsally on inspiratory and expiratory NAPs. When possible, horses were tested again after AF resection surgery. Results: Twenty-one consecutive cases with suspected AF collapse were tested. Suturing the AFs dorsally had a significant effect on expiratory NAPs (p < 0.001), but not on inspiratory NAPs. Expiratory NAPs decreased from baseline (mean ± SD) 35.8 ± 8.81 cmHO to 20.1 ± 7.04 cmHO after suturing AFs dorsally; to 13.3 ± 2.29 cmHO after complete AF resection in 13 available horses. Conclusions: Not all horses were available for NAP testing post-operatively. Conclusions: NAP measurements provided a precise objective means to determine whether a horse was affected with AF collapse and assess improvement in airway function after surgery. AF collapse caused a moderate to marked expiratory airway obstruction in many affected racehorses. Unassigned: Die klinische Beurteilung eines Kollapses der Flügelknorpel (AF) basiert derzeit auf der subjektiven Einschätzung einer Verbesserung der Atmung und der Atemgeräusche nach dorsaler Fixierung der Flügelknorpel durch Nähte. Unassigned: Die Verwendung des nasopharyngealen Atemwegsdrucks (NAP) sollte als objektive Methode zur Beurteilung eines Flügelknorpelkollapses während der Belastung untersucht werden. Zudem könnten NAP‐Messungen eine präzise Einschätzung des Ausmaßes der Atemwegsobstruktion sowie der Reaktion auf eine chirurgische Behandlung ermöglichen. Methods: Prospektive klinische Studie an aktiv rennenden Standardbred‐Trabern. Methods: Die getesteten Traber wurden zunächst mit einem Herzfrequenzmesser ausgestattet und auf dem Laufband über ca. 2000 Meter aufgewärmt. Anschließend wurde ein analoger Drucksensor im Nasopharynx platziert. NAPs wurden kontinuierlich gemessen – vor und nach dorsaler Fixierung der Flügelknorpel – während die Pferde bei einer Herzfrequenz ≥ 200 bpm für 2 Minuten unter identischen Bedingungen trabten. Für jedes Pferd wurden die maximalen inspiratorischen und exspiratorischen NAPs ermittelt. Zur Analyse des Effekts der dorsalen Fixierung auf die inspiratorischen und exspiratorischen NAPs wurde eine zweifaktorielle ANOVA mit Messwiederholung durchgeführt. Wenn möglich, wurden die Pferde nach chirurgischer Entfernung der Flügelknorpel erneut getestet. Results: 21 aufeinanderfolgende Fälle mit Verdacht auf Flügelknorpelkollaps wurden getestet. Die dorsale Fixierung der Flügelknorpel hatte einen signifikanten Einfluss auf die exspiratorischen NAPs (p < 0,001), jedoch nicht auf die inspiratorischen NAPs. Die exspiratorischen NAPs sanken vom Ausgangswert (Mittelwert ± SD) 35,8 ± 8,81 cmHO auf 20,1 ± 7,04 cmHO nach dorsaler Fixierung und auf 13,3 ± 2,29 cmHO nach vollständiger chirurgischer Entfernung bei 13 verfügbaren Pferden. WICHTIGSTE EINSCHRÄNKUNGEN: Nicht alle Pferde standen für eine postoperative NAP‐Messung zur Verfügung. Unassigned: NAP‐Messungen ermöglichen eine präzise und objektive Bestimmung eines Flügelknorpelkollapses sowie eine Beurteilung der Verbesserung der Atemwegsfunktion nach operativem Eingriff. Ein Flügelknorpelkollaps führte bei vielen betroffenen Rennpferden zu einer moderaten bis ausgeprägten exspiratorischen Atemwegsobstruktion.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-07-08 PubMed ID: 40626894DOI: 10.1111/evj.14556Google 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 article focuses on the objective diagnosis of alar fold collapse in actively racing Standardbred horses using nasopharyngeal airway pressure (NAP) measurements as an objective method for assessing this condition. The study also attempts to determine the effectiveness of airway obstruction and post-surgical treatment.

Methodology

  • The study followed a prospective clinical design involving actively racing Standardbred horses suspected of having an alar fold (AF) collapse.
  • The horses underwent a warm-up exercise on a treadmill and then had an analogue pressure sensor positioned in their nasopharynx.
  • NAP was recorded continuously before and after suturing the AFs dorsally. This was done while the horses were trotted at a heart rate exceeding 200 bpm for 2 min under identical conditions.
  • Both the peak inspiratory and expiratory NAPs were recorded for each horse.
  • A two-way repeated measures ANOVA was employed to analyze the effect of suturing the AFs dorsally on the inspiratory and expiratory NAPs.
  • Whenever possible, horses underwent testing again after AF resection surgery.

Results

  • The study tested twenty-one consecutive cases with suspected AF collapse.
  • It was found that suturing the AFs dorsally significantly affected the expiratory NAPs but not the inspiratory ones.
  • Expiratory NAPs decreased from a baseline average of 35.8 cmHO to 20.1 cmHO after suturing and then to 13.3 cmHO after complete AF resection in the 13 available horses.

Conclusion

  • Not all horses were available for NAP testing post-surgery, posing a limitation to the study.
  • The study concluded that NAP measurements offer a precise objective means to determine whether a horse has AF collapse and to assess any improvement in airway function following surgery.
  • The researchers found that AF collapse often resulted in moderate to severe expiratory airway obstruction in many of the affected racehorses.

This research is significant as it provides a precise and objective method for diagnosing and assessing the severity of AF collapse in horses, contributing to improved treatment and recovery strategies for affected horses.

Cite This Article

APA
Strand E, Vermedal H, Olsen HMB, Fjordbakk CT, Fretheim-Kelly ZL. (2025). Objective diagnosis of alar fold collapse in active Standardbred trotting racehorses using nasopharyngeal airway pressure measurements. Equine Vet J. https://doi.org/10.1111/evj.14556

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Strand, Eric
  • Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Vermedal, Hanna
  • Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Olsen, Hanna Margrethe Berg
  • Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Fjordbakk, Cathrine Taule
  • Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Fretheim-Kelly, Zoe Louise
  • Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ås, Norway.

Grant Funding

  • H-19-47-472 / Swedish-Norwegian Foundation for Equine Research
  • 311955 / Norwegian Research Foundation

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