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Topic:Airway Disease
Airway disease in horses is defined as a respiratory condition marked by inflammation and narrowing of the lower airways, leading to symptoms like coughing, increased mucus production, and reduced performance. This condition, which includes forms such as inflammatory airway disease (IAD) and recurrent airway obstruction (RAO), can significantly impact a horse’s respiratory efficiency and overall health.
This page compiles peer-reviewed research studies and clinical insights that explore the pathophysiology, diagnostic techniques, and effective treatment protocols to manage and improve equine respiratory health.
Nasopharyngeal and laryngopharyngeal collapse: intra- and interrater agreement supports novel endoscopic scoring classifications in horses. The contribution of reduced airway patency from heightened inspiratory pressure or active muscular contraction to the pathophysiology of pharyngeal collapse is unknown. Existing classifications refer to the entire pharyngeal region; however, anatomical differences are evident between rostral and caudal collapse. Novel classifications and grading systems are proposed to differentiate 2 pathologies: nasopharyngeal collapse (NPC; collapse of ≥ 1 pharyngeal wall rostral to the tip of the epiglottis; grades 0 through 4), and laryngopharyngeal collapse (LPC; collapse of ≥ 1 pharyngeal wall cauda...
Association of submaximal exercise test variables with diagnosis of asthma in a mixed-breed cohort of leisure horses. Submaximal exercise tests (SET) are used to assess respiratory health in various contexts. The diagnostic value of SETs for the assessment of asthma in the field remains uncertain. Objective: A SET helps distinguish healthy horses and asthma phenotypes. Methods: Twenty-six privately owned mixed-breed leisure horses of a clinical cohort. Horses were healthy (8) or diagnosed with mild (miEA) (4), moderate (modEA) (7), or severe asthma (sEA) (7) according to history, clinical examination, and bronchoalveolar lavage fluid (BALF) cytology. Methods: Cross-sectional study using clinical data and samp...
Randomized study of the effects of testosterone administration on severity of asthma in horses. Low testosterone concentrations are associated with poor lung function in human asthmatics, and androgen administration improves airway obstruction in women with asthma. Objective: Testosterone improves clinical scores, lung function, airway neutrophilia, and airway remodeling in horses with severe asthma. Methods: Ten horses affected by severe asthma from a research herd. Methods: In a randomized, blinded, crossover study, horses received dexamethasone (0.06 mg/kg PO q24h for 10 days) or a single intramuscular injection of testosterone cypionate (0.35 mg/kg), with a 2-week washout period. ...
Airway Lipid Mediators in Horses: Baseline Bronchoalveolar Lavage Fluid Profiles and Effects of EPA and DHA-rich Microalgae Oil Supplementation. We investigated how dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affect airway inflammation, bronchoalveolar lavage fluid (BALF) lipid mediators and red blood cell fatty acids in horses. Increased BALF neutrophils are a hallmark of airway inflammation, commonly associated with equine asthma. The long-chain n-3 PUFAs EPA and DHA are essential nutrients and precursors of specialized pro-resolving mediators (SPMs) that regulate inflammatory responses. In this prospective field trial, we assigned horses to three diets, including...
Circulating Cell-Free RNA Reflects Immune-Associated and Airway Remodeling Signatures in Equine Asthma. Circulating cell-free RNA (cfRNA) has emerged as a promising minimally invasive biomarker capable of capturing transcripts originating from multiple tissues and cell types, but its utility in chronic inflammatory airway diseases remains poorly understood. Equine asthma (EA), a naturally occurring respiratory disease that shares key clinical and immunopathological features with human asthma, provides a valuable comparative model for evaluating plasma cfRNA in this context. We performed transcriptomic profiling of plasma cfRNA from horses with EA and healthy controls and compared these findings ...
The Impact of a Horse Kick: A Systematic Review of Horse-Related Maxillofacial Trauma. : To systematically review the evidence on horse-related maxillofacial trauma, with emphasis on horse-kick injuries, anatomical patterns, associated injuries, management, outcomes, and prevention. : This systematic review followed the PRISMA 2020 statement. PubMed/MEDLINE, Scopus, Web of Science, and the Cochrane Library were searched for original clinical studies reporting facial, craniofacial, orbital, dental, or maxillofacial injuries related to horse-associated activities. Data were extracted on study characteristics, demographics, mechanism, mounted/unmounted status, anatomical site, asso...
Mares with severe equine asthma exhibit a narrower trachea than geldings in a retrospective radiographic study of 189 horses. To evaluate potential relationships between sex, asthma severity, and tracheal diameter in adult horses through the use of thoracic radiography. Unassigned: This was a retrospective case-control study of horses that underwent thoracic radiography at the Université de Montréal from 2018 through 2024. Horses were classified as control, mild/moderate asthma, or severe asthma (SEA) according to the latest consensus statement on equine asthma. To account for radiographic magnification and body size, standardized ratios of tracheal diameter relative to the fifth thoracic vertebral body length and ...
Pneumocoele sinus: Computed tomographic findings and surgical approach in a 2-year-old Cob filly. Pneumosinus dilatans and pneumocoele sinus describe abnormal hyperpneumatisation of paranasal sinuses, with the latter being accompanied by thinning of bony walls. Although recognised in human and equine medicine, to the authors' knowledge, this condition's computed tomography (CT) findings and successful surgical approach in horses have not previously been reported in conjunction. Advanced imaging, particularly CT, is pivotal for identifying abnormal sinus expansion and associated nasal obstruction. Methods: Case report. Conclusions: A 2-year-5-month-old Cob filly presented with a 1-month his...
Effects of Nebulized Alpha-2 Macroglobulin in Horses with Lower Airway Inflammation. Equine asthma is a chronic inflammatory airway disease with limited safe long-term treatments. Alpha-2-macroglobulin (A2M), a natural anti-inflammatory protease inhibitor, may provide a novel non-steroidal therapeutic option for horses with lower respiratory tract inflammation. Objective: To characterize the impact of nebulization with alpha-2-macroglobulin (A2M) on clinical signs, bronchoalveolar lavage cytology, and local and systemic cytokine response in horses with lower respiratory tract inflammation. Methods: Thirteen university-owned horses with lower airway inflammation were randomized...
Inhaled Corticosteroids Influence Pulmonary Microbiota in Severe Equine Asthma. The use of inhaled corticosteroids (ICs) could influence the respiratory microbiota. In animals with asthma it is, however, difficult to separate the immunomodulatory effects of ICs from their indirect effects via improvement of ventilation. Our objective was to determine if ICs alter the pulmonary microbiota independently from their effects on lung function, using a blinded, controlled trial in an experimental model of asthma exacerbation in horses. We treated horses with severe asthma with either bronchodilators alone, or in combination with ICs. Twelve horses in exacerbation received long-a...
Effect of exercise-related nasopharyngeal disorders on upper airway function in racehorses. Exercise-related upper respiratory tract (URT) disorders are frequently diagnosed in racehorses. Treatment recommendations are routinely based on subjective assessment of clinical evaluation and exercising endoscopy findings. Objective: To objectively investigate how palatal instability (PI), intermittent dorsal displacement of the soft palate (iDDSP), alar fold collapse (AFC), and nasopharyngeal collapse (NPC) affect upper airway function during exercise in racehorses. Methods: Observational study with case-control comparisons. Methods: Inspiratory and expiratory tracheal pressures (cmHO) wer...
Biomarkers of equine asthma: A review of the current literature. Equine Asthma (EA) is a common, lower airway disease. Yet current diagnostic standards rely on bronchoalveolar lavage fluid (BALF) cytology, which is moderately invasive and not always feasible in field conditions. This review aimed to synthesize current evidence on candidate biomarkers of EA, with a primary focus on blood-based matrices and BALF, while also including data on biomarkers measured in tracheal wash (TW), saliva and exhaled breath condensate (EBC), where available. Searches were performed in PubMed, Scopus and Google Scholar, and original studies in horses with mild-to-moderate or...
The effects of upper airway obstruction on oxygen consumption and ventilatory variables in Colombian criollo horses. 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 ...
Neuroimmune Mechanisms in Equine Asthma: Primary Inflammatory Triggers, Neuroimmune Modulation and Chronic Airway Remodelling. Equine asthma is a chronic inflammatory disease of the lower respiratory tract, primarily associated with inhalation of organic dust, microbial particles and environmental aeroantigens. Although the inflammatory and immunological mechanisms underlying equine asthma have been extensively investigated, the potential contribution of neuroimmune pathways remains poorly understood. In humans and rodent models, asthma is increasingly recognised as a disorder involving complex bidirectional interactions between the nervous and immune systems. Sensory nerve activation, neuropeptide release, autonomic ...
Oscillometric assessment of bronchodilator response in horses with severe asthma during remission. During clinical remission of severe equine asthma (SEA), affected animals can be challenging to distinguish from healthy horses. In humans, the degree of bronchodilation achieved with a β-adrenergic bronchodilator is helpful in differentiating asthmatics from healthy subjects. Objective: To determine whether the response to an inhaled bronchodilator improves the sensitivity of oscillometry in detecting subclinical airway obstruction in horses with asthma. Methods: In vivo experiments. Methods: Nine control university-owned horses and 10 SEA horses in remission from a research herd were studie...
Bronchoalveolar lavage changes the ultrasonographic and radiographic appearances of lungs in adult horses. To describe the effect of bronchoalveolar lavage (BAL) on the ultrasonographic and radiographic appearances of lungs of horses being evaluated for equine asthma syndrome (EAS). Unassigned: Prospective observational study enrolling 32 adult horses evaluated for EAS. Ultrasonographic and radiographic examinations of the thorax were performed before and within 3 hours following BAL and scored using previously validated systems. The differences in scores between groups (normal, mild EAS, moderate/severe EAS) were evaluated through the Kruskal-Wallis test, and the differences in scores before and f...
The transition from winter to spring has an impact on the airway metabolome profile of asthmatic horses. Equine asthma is a chronic, non-infectious inflammatory disease of the lower airways in horses, classified as mild to moderate (MEA) or severe (SEA). Its pathogenesis is not fully understood and is influenced by environmental and seasonal factors. In this cross-sectional study, seasonal effects on the bronchoalveolar lavage fluid (BALF) metabolome were investigated in asthmatic and non-asthmatic horses. The metabolome of 230 BALF samples from horses across different seasons, classified as cytologically unremarkable (CUA), MEA, or SEA, was analyzed using proton nuclear magnetic resonance spectr...
Tracheal wash culture is not associated with bronchial infection, remodelling or inflammation in horses with asthma. Antimicrobials are commonly prescribed for the treatment of equine asthma, despite limited evidence supporting their use. Tracheal wash (TW) bacterial culture results are known to influence antimicrobial prescription decisions. Objective: To determine whether a positive TW bacterial culture in horses with asthma is associated with bronchial infection or colonisation, increased bronchial remodelling and airway inflammation by evaluating the presence of bacteria and airway remodelling in endobronchial biopsies, as well as bronchoalveolar lavage fluid (BALF) cytology and tracheal mucus scores. Me...
Differences in Redox Biomarkers in Bronchoalveolar Lavage Fluid of Leisure Horses With and Without Severe Equine Asthma: Preliminary Results. Equine asthma is a common chronic respiratory disease characterized by airway inflammation and oxidative imbalance, particularly in its severe form. The aim of this study was to evaluate pro-oxidative substances, oxidative products, and antioxidant defense biomarkers in bronchoalveolar lavage fluid (BALF) from horses with and without a history of severe equine asthma (SEA). This prospective observational study included 21 leisure horses classified as SEA or non-SEA based on clinical history and BALF cytology. Bronchoalveolar lavage fluid was analyzed for derivatives of reactive oxygen metaboli...
An in-hospital clinical trial assessing nebulized lidocaine compared to saline for treatment of asthma in horses. Corticosteroids are the main pharmacologic treatment for equine asthma (EA) but may have adverse effects in metabolically unstable horses. Recent pilot studies support the use of nebulized lidocaine as an alternative treatment option. Objective: Nebulized lidocaine will improve EA-associated clinical variables and airway inflammation. Methods: Twenty client-owned horses diagnosed with EA. Methods: Randomized, blinded, in-hospital study comparing 1 mg/kg preservative-free 4% lidocaine (n = 10) nebulized via Flexineb (twice daily for 7 doses) to 0.9% saline control (n = 10). Clinical examin...
Multi-Kingdom Fecal Microbiota Alterations in Horses with Severe Equine Asthma. Severe equine asthma (SEA) is a chronic inflammation of airways affecting ~14-20% of adult horses in the Northern Hemisphere. SEA is characterized by a mixed phenotype of T helper cell responses with marked neutrophilia in the bronchoalveolar lavage fluid (BALF) of affected horses. Human studies have demonstrated the impact of gut microbiota in many diseases, including asthma susceptibility and severity. However, the potential role of the gut-lung axis in the development and persistence of SEA remains to be determined. This study aimed to identify key bacterial, archaeal, and fungal microbiota...
[Equine laryngeal dysplasia – overview of variable clinical presentation based on 6 cases]. Equine laryngeal dysplasia (ELD) is the umbrella term for various malformations of laryngeal structures that arise from the 4th and 6th branchial arches during embryogenesis. The disease is rare and may be subclinical. In symptomatic patients with clinical signs, the clinical presentation is highly variable and is the result of functional limitations of the larynx as well as of the esophageal sphincter. The spectrum of signs may range from respiratory changes such as abnormal respiratory noise, coughing, and at times dyspnea all the way to poor performance, dysphagia, aerophagia, and colic. Th...
Proteomic profiling of equine airway mucus reveals compositional changes in asthmatic phenotypes. Mucus hypersecretion and accumulation are hallmark features of equine asthma (EA), a meaningful respiratory disorder in horses occurring in mild to moderate (MEA) and severe (SEA) forms. Changes of the proteomic composition of airway mucus in EA are poorly understood. Using label-free quantitative liquid chromatography-mass spectrometry, we analyzed airway mucus from SEA (n = 10), MEA (n = 6), and healthy (n = 8) horses. We identified and quantified 2,275 proteins including gel-forming mucins MUC5AC and MUC5B and membrane-bound mucins MUC1 and MUC4. Compared with healthy controls, ...
RNA-seq evaluation of equine alveolar macrophages and monocyte-derived macrophages exposed to an inflammatory stimulus (short communication). Macrophage populations in the lung, including resident alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs), recognize the inhaled particulates in barn dust that cause severe equine asthma and orchestrate an immune response though the cytokines they produce. Despite their importance, the specific contributions of these macrophage subsets to lower airway inflammation remain poorly understood. This exploratory in vitro study investigated the likely contributions of AMs and MDMs from healthy horses to the early inflammatory response using RNA-seq. If biologically importan...
Barrel racing horses demonstrate a high incidence of nonclinical postrace airway disorders. To describe the prevalence of postrace airway abnormalities in a population of barrel racing horses competing in Oklahoma. Unassigned: A descriptive field study was conducted at a single event. Horses underwent resting endoscopy within 60 minutes of competition. Recordings were evaluated and numerical and/or binary scores assigned for pharyngeal lymphoid hyperplasia, recurrent laryngeal neuropathy, dorsal displacement of the soft palate, epiglottic entrapment, and exercise-induced pulmonary hemorrhage. Clients completed a questionnaire detailing the horse's medical history and run time. A line...
A Portable Fluorometer Detects Significantly Elevated Cell-Free DNA in Tracheal Wash and Bronchoalveolar Lavage Fluid in Horses with Severe Asthma. Severe equine asthma (sEA) is characterized by increased lower airway neutrophils that contribute to dysregulated inflammation through the release of cytokines, reactive oxygen species and neutrophil extracellular traps (NETs). NETs are composed of cell-free DNA (cfDNA) intercalated with enzymatic proteins and are known to be increased in the lower airway of asthmatic horses. The objectives of this study were two-fold: 1. Determine if cfDNA can be accurately measured in equine bronchoalveolar lavage fluid (BALF) and tracheal wash (TW) with a Qubit 4 fluorometer. 2. Determine whether Qubit-meas...
Field-applicable low-intensity exercise induces bronchodilation in horses with severe asthma. Airway dysfunction in severe equine asthma (SEA) often results in early retirement or euthanasia of affected horses. Exercise-induced bronchodilation occurs in horses with SEA after intense treadmill exercise, but the effects of a lighter, field-applicable, training regimen remain largely unexplored. Objective: To evaluate the impact of submaximal aerobic exercise on airway obstruction during exacerbation of SEA. Methods: The preliminary phase explored the effects of a 25-min standardised exercise on the lung function of eight SEA horses. As notable bronchodilation occurred, the results were c...
Complications of Respiratory Surgery in the Horse. Respiratory surgery and procedures typically focus on conditions of the upper airway that restrict airflow at rest or exercise. This article focuses on respiratory anatomy and common surgeries of the trachea and larynx in horses. The trachea serves as the airway conduit from the larynx to the bronchi. A variety of upper airway disorders can lead to obstruction and in these instances, tracheotomy is typically utilized to bypass these obstructions and maintain airway patency. Emergency and permanent tracheotomy procedures are discussed. Other common upper airway operations, such as laryngotomy, ...
Steamed hay for the prevention of severe equine asthma exacerbations. Steaming hay reduces respirable particles and is commonly used to feed horses with asthma. However, it showed inconsistent benefits in clinical studies. Objective: (1) To assess the effects of steamed hay on lung function and airway inflammation in horses with severe equine asthma (SEA) in remission; (2) To compare these effects with a dry hay diet. Methods: Cross-over in vivo experiment. Methods: Horses were fed steamed and dry hay for 4 weeks in a prospective, cross-over study, with a 4-week washout period. Lung function, bronchoalveolar lavage (BALF) cytology, and a 23-point weighted clin...
