Journal of veterinary internal medicine2026; 40(3); aalag111; doi: 10.1093/jvimsj/aalag111

The effects of upper airway obstruction on oxygen consumption and ventilatory variables in Colombian criollo horses.

Massie, SL
·
Zuluaga-Cabrera, AM
·
Bayly, WM
·
Vega, LCC
·
Vanegas, VEC
·
Léguillette, R

Abstract: While conditions associated with upper airway obstruction (UAO) are reported in Colombian Criollo horses, their effect on ventilation and performance is unknown. Objective: To investigate how oxygen consumption ($dot{rm V}$O2), ventilation,, and exercise-induced pulmonary hemorrhage (EIPH) are affected by UAO in horses performing at natural gaits. Methods: Twenty-three client-owned Colombian Criollo horses. Methods: A cross-sectional observational study assigned horses to a control (C), or UAO group after overground endoscopy. All horses performed a standardized submaximal exercise test while wearing an ergospirometry facemask. Post-exercise blood lactate concentration and bronchoalveolar lavage cytological results were assessed. Results: Twelve horses had UAO, with 6/12 having multiple diagnoses. Recurrent laryngeal neuropathy was most prevalent (83%), followed by nasopharyngeal collapse (42%). Mean $dot{rm V}$O2 and minute ventilation were not different between C (79.4 ± 22.0 mL/(kg min); 723 ± 203 L/min) and UAO (88.2 ± 23.2 mL/(kg min); 648 ± 190 L/min). UAO resulted in lower peak inspiratory (25.2 ± 5.3 L/s, P = .01) and expiratory (33.6 ± 7.3 L/s, P = .03) flow than C (28.3 ± 10.0 and 38.0 ± 9.0 L/s). Longer inspiratory and expiratory durations in UAO resulted in lower breathing frequency (76.0 ± 16.0 vs. 89.2 ± 12.4 breaths/min). Post-exercise [lactate] was greater (P = .05) in UAO (6.8 [4.6-9.3] mmol/L) than C (3.5 [3.0-5.5] mmol/L). No evidence of EIPH was noted. Conclusions: Horses with UOA had marked changes in ventilation, however, $dot{rm V}$O2 and EIPH severity were not different to C, likely because the exercise was submaximal.

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Publication Date: 2026-06-17 PubMed ID: 42308559PubMed Central: PMC13275017DOI: 10.1093/jvimsj/aalag111Google Scholar: Lookup

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Summary

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Overview

This study examined how upper airway obstruction (UAO) impacts oxygen consumption, breathing patterns, and exercise-induced lung hemorrhage in Colombian Criollo horses during natural gait exercise.
The research found that while UAO significantly altered breath flow and timing, it did not reduce overall oxygen consumption or increase lung bleeding in mildly strenuous exercise conditions.

Background

Upper airway obstruction (UAO) includes physical restrictions or collapses in the horse’s upper airway that can affect breathing.
Colombian Criollo horses often show conditions causing UAO such as recurrent laryngeal neuropathy and nasopharyngeal collapse.
Although UAO is known to influence airway function, its direct impact on oxygen use, ventilation characteristics, and exercise-induced pulmonary hemorrhage (EIPH) in this specific breed during natural gaits was previously unknown.

Objectives

To determine the effects of UAO on:

Oxygen consumption (VO2)
Ventilatory variables like airflow rates and breathing frequency
The occurrence or severity of exercise-induced pulmonary hemorrhage (EIPH)

The aim was to assess these variables during submaximal exercise that reflects natural gaits.

Methods

Subjects: 23 client-owned Colombian Criollo horses grouped into control or UAO categories based on overground endoscopy diagnosis.
Testing:

All horses undertook a standardized submaximal exercise test wearing an ergospirometry facemask to measure oxygen use and ventilation.
Post-exercise measurements included blood lactate concentration and cytological analysis of bronchoalveolar lavage fluid to check for EIPH.

UAO diagnoses included recurrent laryngeal neuropathy (most common) and nasopharyngeal collapse.

Results

12 horses had UAO; 6 had more than one airway obstruction condition.
Oxygen consumption (VO2) and minute ventilation (total air volume breathed per minute) were not significantly different between UAO and control horses:

Control VO2: 79.4 ± 22.0 mL/(kg·min)
UAO VO2: 88.2 ± 23.2 mL/(kg·min)
Control minute ventilation: 723 ± 203 L/min
UAO minute ventilation: 648 ± 190 L/min

However, horses with UAO showed:

Lower peak inspiratory flow (breathing in volume per second): 25.2 ± 5.3 L/s vs. 28.3 ± 10.0 L/s in controls
Lower peak expiratory flow (breathing out volume per second): 33.6 ± 7.3 L/s vs. 38.0 ± 9.0 L/s in controls
Longer inspiratory and expiratory times, resulting in lower breathing frequency (76.0 ± 16.0 breaths/min compared to 89.2 ± 12.4 breaths/min in controls)

Post-exercise blood lactate (indicator of anaerobic metabolism/physical stress) was higher in the UAO group (6.8 [4.6-9.3] mmol/L) than controls (3.5 [3.0-5.5] mmol/L), suggesting more metabolic stress despite similar oxygen consumption.
No evidence of exercise-induced pulmonary hemorrhage (EIPH) was found in any horses regardless of airway status.

Conclusions

UAO affects ventilation mechanics by reducing peak airflow rates and decreasing breathing frequency but prolonging breath duration.
Despite these ventilatory changes, overall oxygen consumption during submaximal, natural gait exercise remains comparable to healthy controls.
The absence of increased EIPH in UAO horses during submaximal exercise suggests that airway obstruction at mild exercise intensity does not worsen lung bleeding.
Higher blood lactate levels in UAO horses indicate increased anaerobic metabolism or increased effort under obstruction despite similar oxygen use, highlighting subtle performance impacts.
These findings are crucial for understanding respiratory physiology in Colombian Criollo horses and may guide management of airway conditions without severely limiting submaximal exercise performance.

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APA

Massie SL, Zuluaga-Cabrera AM, Bayly WM, Vega LCC, Vanegas VEC, Léguillette R. (2026). The effects of upper airway obstruction on oxygen consumption and ventilatory variables in Colombian criollo horses. J Vet Intern Med, 40(3), aalag111. https://doi.org/10.1093/jvimsj/aalag111

Publication

Journal of veterinary internal medicine

ISSN: 1939-1676

NlmUniqueID: 8708660

Country: England

Language: English

Volume: 40

Issue: 3

PII: aalag111

Researcher Affiliations

Massie, Shannon L

Faculty of Veterinary Medicine, University of Calgary, Calgary T2N 1N4, Canada.

Zuluaga-Cabrera, Angélica María

GISCA Research Group, Institución Universitaria Visión de las Américas, 050031, Laureles, Medellín, Colombia.

Bayly, Warwick M

Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, United States.

Vega, Lady Consuelo Calixto

Universidad de La Salle, 110231, Chapinero, Bogotá, Colombia.

Vanegas, Viviana Elena Castillo

Vitalab diagnostico Veterinario, Rionegro, Antioquia-colombia GISCA research group, Institución Universitaria Visión de las Américas, 054048, Llanogrande, Rionegro, Colombia.

Léguillette, Renaud