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.
Dynamic nasopharyngeal collapse in horses: What we know so far. Dynamic nasopharyngeal collapse (NPC) is an obstructive upper airway disease that affects mainly the inspiratory phase of respiration in horses undergoing strenuous exercise. It occurs when the neuromuscular activity of the nasopharynx is overwhelmed by the intense negative pressures generated during exercise. This leads to collapse of at least one of the four components of the nasopharynx which is comprised of the two lateral walls, the dorsal roof and the ventral soft palate. As a result, the airway diameter and thus airflow become compromised. Even small changes in the airway diameter produ...
Investigation of nasal epithelial cells as a surrogate for bronchial epithelial cells in the research of equine asthma. Equine asthma, previously known as Recurrent Airway Obstruction (RAO) or Inflammatory Airway Disease (IAD), is an often-debilitating condition that may severely affect both performance and quality of life. Research is hindered by the low sample numbers of subjects recruited to studies, a consequence in part of the invasive nature of the sampling methods of bronchial brushing and biopsy. We present an alternative method of sampling equine airway epithelial cells, the 'nasal brush method' (NBM). Obtained by light brushing of the ventral meatus whilst the horse is under standing sedation, these c...
A real-time PCR assay for the quantification of Mycoplasma equirhinis in tracheal wash samples from Thoroughbred horses. is the predominant equine sp. isolated from clinically normal horses and is suspected to be associated with inflammatory airway disease in which cough is the primary sign. Quantitative evaluation of bacterial counts is useful in assessing the association between the bacteria in samples and observed clinical signs, but this evaluation has been difficult with conventional culture methods of given the need for pre-enrichment using liquid cultures. We established a quantitative real-time PCR (qPCR) assay for the quantification of , targeting the hypothetical protein FJM08_00025. We confirmed it...
Associations between postrace atrial fibrillation and measures of performance, racing history and airway disease in horses. Atrial fibrillation (AF) is the most common performance limiting arrhythmia in racehorses. High dose exercise and airway disease promote AF in humans. Few studies have investigated epidemiological factors associated with AF in horses. Objective: Explore variables relating to performance, exercise volume and postrace endoscopic findings in horses with AF. Methods: A total of 164 horses with poor race performance and postrace AF were compared to 321 horses with poor performance without AF (PP) and 314 horses performing to expectation (TE). Methods: Horse-level and race-level variables for horses...
Molecular and Cellular Evaluation of Horses With Summer Pasture Associated Asthma Syndrome. Equine asthma is an airway disease that affects a large number of horses annually leading to considerable economic losses in the horse industry. Despite advances in research in this area, there is still a lack of information on its etiology and molecular characterization in pasture associated asthma. The objective of the current study was to characterize the inflammatory disease of lower airways in horses maintained on pasture through cytologic and immunologic profile during the summer in a tropical environment by analysis of the gene expression of Th1 cytokines (IFN- λ, IL-8), Th2 cytokines ...
Airway Hyperresponsiveness, but Not Bronchoalveolar Inflammatory Cytokines Profiles, Is Modified at the Subclinical Onset of Severe Equine Asthma. Airway hyperresponsiveness (AHR) and inflammation are both observed in human and equine asthma. The aim of this study was to assess the timeline and relationship of both features at the subclinical onset of severe equine asthma (SEA). First, the repeatability of the pulmonary function test (PFT) using impulse oscillometry system, and the methacholine bronchoprovocation test (BPT) were assessed at a 1-day interval on six SEA horses in clinical remission and six control horses. Then, clinical and ancillary tests were performed before and after a 1-week low-dust environmental challenge, including...
Co-Occurrence of Severe Equine Asthma and Palatal Disorders in Privately Owned Pleasure Horses. According to the "unified or united airway disease" theory, diseases in the upper and lower airways frequently co-occur because they represent a single morphological and functional unit. Palatal disorders (PDs) and severe equine asthma (SEA) are frequent diseases that, respectively, affect upper and lower equine airways; however, clinical studies focusing on the co-occurrence of PDs and SEA are limited. The present study investigated the prevalence of PDs in horses affected by SEA, and whether prevalence decreased after SEA treatment. Forty-six privately owned horses affected by SEA in exacerb...
Initial investigation of molecular phenotypes of airway mast cells and cytokine profiles in equine asthma. Equine asthma is a naturally occurring lung disease characterized by chronic, partially reversible airway obstruction, pulmonary remodeling, and lower airway inflammation. Asthma is currently divided into two major groups, mild to moderate asthma (mEA) and severe asthma (sEA), but further subtyping by phenotype (i.e., clinical presentation) and/or endotype (i.e., cellular mechanisms) may be warranted. For this study, we were interested in further investigation of cellular and inflammatory characteristics of EA, including airway mast cells. The purpose of this study was to: (1) compare mast cel...
Impact of Lower Airway Inflammation on Fitness Parameters in Standardbred Racehorses. Mild-moderate equine asthma (MEA) is a common respiratory disorder among racehorses, characterized by lower airway inflammation. Although it is generally agreed that MEA causes poor performance, contrasting results have been reported about the effects of tracheal mucus and the leukocyte populations of the bronchoalveolar lavage (BAL) on performance. This study aims to investigate the associations between airway inflammation and fitness parameters measured during an incremental treadmill test on Standardbred racehorses. For this purpose, the clinical records of 116 Standardbreds subjected to a ...
Nebulized glycosylated caffeic acid phenylether ester attenuation of environmental particulate-induced airway inflammation in horses. The objective of this study was to determine the extent that nebulized glycosylated caffeic acid phenylether ester-4-O-alpha-D-glucopyranoside (G-CAPE) attenuates particulate-induced airway inflammation in healthy horses. Our hypothesis was that nebulization with G-CAPE would result in improved respiratory scores, higher arterial oxygen partial pressure, and less inflammatory airway infiltrates in horses with induced airway inflammation, compared with untreated controls. Five healthy adult horses were housed inside a climate controlled, closed barn on straw bedding and fed moldy grass hay for...
Neutrophil Extracellular Vesicles and Airway Smooth Muscle Proliferation in the Natural Model of Severe Asthma in Horses. Extracellular vesicles (EVs) contribute to intercellular communication through the transfer of their rich cargo to recipient cells. The EVs produced by LPS-stimulated neutrophils from healthy humans and horses increase airway smooth muscle (ASM) proliferation, but the roles of neutrophil EVs in asthma are largely unexplored. The aim of this study was to determine whether neutrophil-derived EVs isolated during the remission or exacerbation of asthma influence ASM proliferation differentially. Peripheral blood neutrophils were collected during remission and exacerbation in eight horses affected ...
Upper and Lower Airways Evaluation and Its Relationship with Dynamic Upper Airway Obstruction in Racehorses. Dynamic upper airway obstructions (DUAO) are common in racehorses, but their pathogenetic mechanisms have not been completely clarified yet. Multiple studies suggest that alterations of the pharyngo-laryngeal region visible at resting endoscopy may be predictive of the onset of DUAO, and the development of DUAO may be associated with pharyngeal lymphoid hyperplasia (PLH), lower airway inflammation (LAI) and exercise-induced pulmonary hemorrhage (EIPH). The present study aims to investigate the possible relationship between the findings of a complete resting evaluation of the upper and lower ai...
Association between dynamic upper airway obstructions and fitness parameters in Standardbred racehorses during high-speed treadmill exercise. To evaluate the association between the severity of dynamic upper airway obstruction (DUAO) and selected fitness parameters in Standardbred racehorses measured by treadmill test. 191 Standardbred racehorses that underwent a standardized diagnostic protocol for poor performance evaluation between 2002 and 2021 at the Veterinary Teaching Hospital, University of Milan. Horses underwent a diagnostic protocol including clinical examination, lameness evaluation, laboratory analyses, ECG, resting upper airway endoscopy, metabolic incremental treadmill test, high-speed treadmill endoscopy, postexercis...
The Immune Mechanisms of Severe Equine Asthma-Current Understanding and What Is Missing. Severe equine asthma is a chronic respiratory disease of adult horses, occurring when genetically susceptible individuals are exposed to environmental aeroallergens. This results in airway inflammation, mucus accumulation and bronchial constriction. Although several studies aimed at evaluating the genetic and immune pathways associated with the disease, the results reported are inconsistent. Furthermore, the complexity and heterogeneity of this disease bears great similarity to what is described for human asthma. Currently available studies identified two chromosome regions (ECA13 and ECA15) a...
Computed tomographic geometrical analysis of surgical treatments for equine recurrent laryngeal neuropathy. To characterize the 3-D geometry of the equine larynx replicating laryngeal hemiplegia and 4 surgical interventions by use of CT under steady-state airflow conditions. Secondly, to use fluid mechanic principles of flow through a constriction to establish the relationship between measured airflow geometries with impedance for each surgical procedure. Methods: 10 cadaveric horse larynges. Methods: While CT scans were performed, inhalation during exercise conditions was replicated for each of the following 5 conditions: laryngeal hemiplegia, left laryngoplasty with ventriculocordectomy, left lary...
Effects of azithromycin on bronchial remodeling in the natural model of severe neutrophilic asthma in horses. Steroid resistance in asthma has been associated with neutrophilic inflammation and severe manifestations of the disease. Macrolide add-on therapy can improve the quality of life and the exacerbation rate in refractory cases, possibly with greater effectiveness in neutrophilic phenotypes. The mechanisms leading to these beneficial effects are incompletely understood and whether macrolides potentiate the modulation of bronchial remodeling induced by inhaled corticosteroids (ICS) is unknown. The objective of this study was to determine if adding azithromycin to ICS leads to further improvement o...
Training associated alterations in equine respiratory immunity using a multiomics comparative approach. Neutrophilic airway inflammation is highly prevalent in racehorses in training, with the term mild to moderate equine asthma (MMEA) being applied to the majority of such cases. Our proposed study is largely derived from the strong association between MMEA in racehorses and their entry into a race training program. The objectives of this study are to characterise the effect of training on the local pulmonary immune system by defining the gene and protein expression of tracheal wash (TW) derived samples from Thoroughbred racehorses prior to and following commencement of race training. Multiomics...
Airway remodeling in horses with mild and moderate asthma. There is a remodeling of the central airways in horses with severe asthma but whether a similar process occurs in horses with the mild or moderate asthma (MMA) is unknown. Objective: To evaluate lesions affecting the central airways of horses with MMA. Methods: Twelve horses with MMA and 8 control horses. Methods: Case-control retrospective study of horses classified as MMA affected or controls based on history and bronchoalveolar lavage fluid cytology. Endobronchial biopsies were analyzed using histomorphometry and a semiquantitative histologic scoring system. Results: Histomorphometry identi...
Evaluation of the airway mechanics of modified toggle laryngoplasty constructs using a vacuum chamber airflow model. To evaluate the airway mechanics of modified toggle LP constructs in an airflow chamber model and compare these to the airway mechanics of standard LP constructs. Methods: Ex-vivo experimental study. Methods: Fifty-one equine cadaveric larynges. Methods: Bilateral LP constructs were performed using a modified toggle (n = 23) or a standard (n = 21) LP technique. Constructs were tested in an airflow model before and after cyclic loading which was designed to mimic postoperative swallowing. The cross-sectional area (CSA), peak translaryngeal airflow (L/s), and impedance (cmH 0/L/s) were deter...
Inspiratory muscle training for the treatment of dynamic upper airway collapse in racehorses: A preliminary investigation. Exercise-induced upper airway collapse (UAC) probably occurs when the stabilising muscles of the upper airway are unable to withstand the dramatic changes in airflow and pressure that occurs during exercise. In racehorses, the mainstay of treatment is surgical intervention. In human athletes, exercise-induced laryngeal obstruction has been treated successfully with inspiratory muscle training (IMT). The aims of this study were: (1) to assess the feasibility of IMT in racehorses; and (2) describe the exercising endoscopy findings pre- and post-IMT in racehorses diagnosed with dynamic UAC. Horse...
Glucocorticoid treatment in horses with asthma: A narrative review. Despite substantial research efforts to improve the treatment and outcome of horses with asthma, glucocorticoids (GC) remain the cornerstone of drug treatment of this prevalent disease. The high efficacy of GC to relieve airway obstruction explains their extensive use despite potential deleterious effects. However, much is yet to be uncovered concerning GC use in horses with asthma, including the comparative efficacy of the different drugs, the determination of minimal effective doses and the mechanisms underlying their variable modulation of airway inflammation. The objectives of this structu...
Comparison of Flowmetric Plethysmography and Forced Oscillatory Mechanics to Measure Airway Hyperresponsiveness in Horses. Airway hyperresponsiveness (AHR) is linked to airway inflammation and is considered a key manifestation of mild/moderate equine asthma (EA). The study purpose was to determine whether two modalities of non-invasive lung function testing (FOM-forced oscillatory mechanics vs. FP-flowmetric plethysmography) establish the same clinical diagnosis of AHR in horses, using histamine bronchoprovocation. Nineteen horses (3-25 years, 335-650 kg) with clinical signs suggestive of mild/moderate equine asthma were enrolled. FOM and FP testing was performed in each horse on two consecutive days, using a rand...
The Role of Neutrophils in the Pathophysiology of Asthma in Humans and Horses. Asthma is a common and debilitating chronic airway disease that affects people and horses of all ages worldwide. While asthma in humans most commonly involves an excessive type 2 immune response and eosinophilic inflammation, neutrophils have also been recognized as key players in the pathophysiology of asthma, including in the severe asthma phenotype where neutrophilic inflammation predominates. Severe equine asthma syndrome (sEAS) features prominent neutrophilic inflammation and has been increasingly used as a naturally occurring animal model for the study of human neutrophilic asthma. This...
Asthmatic Disease as an Underlying Cause of Dorsal Displacement of the Soft Palate in Horses. It is important to treat the upper and lower respiratory tracts as a single unit, as lower respiratory tract diseases can often cause upper respiratory functional disorders, whereas upper respiratory obstructions could be a factor in lower respiratory problems. The present study aimed to investigate the hypothesis that asthmatic diseases may be an underlying cause of dorsal displacement of the soft palate in horses. Pleasure or sport horses (n = 57) with a history of asthmatic disease were incorporated in the study. All horses were examined in the exacerbation phase of the asthmatic disease. ...
The Relationship between Lung Inflammation and Aerobic Threshold in Standardbred Racehorses with Mild-Moderate Equine Asthma. Mild-moderate equine asthma (MEA) is a common disease of young racehorses characterized by inflammation of the lower airways diagnosed by cytological examination of bronchoalveolar lavage fluid (BALF), and it is considered an important cause of poor performance. The most common parameter of athletic capacity associated with horse performance is the speed at 4 mmol/L of lactate (VLA4). The aim of the present work was to evaluate the relation between the different BALF inflammatory cells and VLA4 in racehorses affected by MEA. A population of Standardbred racehorses that underwent an accurate pr...
Airway Hyperresponsiveness Is Severe and Persistent in an Equine Model of Neutrophilic Asthma. The research article presents findings on the severity and persistence of airway hyperresponsiveness (AHR) in an equine model of neutrophilic asthma, which is relevant for understanding human asthma and its […]
Conflict Between Direct Experience and Research-Based Evidence Is a Key Challenge to Evidence-Based Respiratory Medicine on British Racing Yards. Inflammatory airway disease (IAD) is a commonly diagnosed but variably defined syndrome of equine lower airway inflammation. The most recent American College of Veterinary Internal Medicine (ACVIM) consensus statement, informed by research evidence, recommends a case definition based on clinical signs (poor performance or occasional coughing of at least 3 weeks duration), increased endoscopically-visible tracheal mucus, and bronchoalveolar lavage cytology, and proposes that the condition should be termed 'mild-moderate equine asthma' (mEA). In British Thoroughbred racehorses, research to date ...
Effects of a propriety oiled mixed hay feeding system on lung function, neutrophilic airway inflammation and oxidative stress in severe asthmatic horses. Hay feeding is considered the main triggering factor for airway obstruction and inflammation in severe equine asthma (SEA). Finding alternate strategies allowing hay feeding while controlling clinical signs of SEA is of importance. The Nutri-Foin Système is believed to decrease inhaled dust by incorporating soybean oil to mechanically processed hay. Objective: We compared airflow obstruction and airway inflammation in horses with SEA fed oiled hay or alfalfa pellet regimen. Methods: Controlled trial in asthmatic research horses. Methods: Twelve horses in exacerbation of SEA from a research he...
Evaluation of histamine-provoked changes in airflow using electrical impedance tomography in horses. Electrical impedance tomography (EIT) generates thoracic impedance images of the lungs and has been used to assess ventilation in horses. This technique may have application in the detection of changes in airflow associated with equine asthma. Objective: The objective was to determine if histamine-induced airflow changes observed with flowmetric plethysmography (Δflow) could also be explained using global and regional respiratory gas flow signals calculated from EIT signals. Methods: Experimental in vivo study. Methods: Six horses, sedated using detomidine were fitted with a thoracic EIT b...
Evaluation of Dynamic Structural Disorders in the Upper Airways and Applied Rein Tension in Healthy Dressage Horses During Riding in Different Gaits and Head-Neck Positions. Flexion of the horse's head and neck during dressage riding reduces the pharyngeal lumen with the risk of increased upper airway resistance and upper airway obstructions. According to the Fédération Equestre Internationale, hyperflexion is achieved through force, whereas the position low-deep-round is nonforced. The objectives of this study were to evaluate (1) applied rein tension and (2) dynamic structural disorders in the upper airways in dressage horses in different gaits and different head-neck positions (HNPs). Overground endoscopy (OGE) and rein tension were evaluated in 13 clinically...