Topic:Asthma
Equine asthma, also known as equine recurrent airway obstruction (RAO) or heaves, is a chronic respiratory condition affecting horses. It is characterized by airway inflammation, mucus production, and bronchoconstriction, leading to clinical signs such as coughing, nasal discharge, and labored breathing. The condition is often exacerbated by environmental factors such as dust, mold, and pollen, which can trigger an immune response in susceptible horses. Equine asthma is managed through environmental modifications, medical treatments, and sometimes dietary adjustments to alleviate symptoms and improve respiratory function. This page compiles peer-reviewed research studies and scholarly articles that explore the pathophysiology, diagnosis, and management strategies of equine asthma.
Increased Weekly Mean PM2.5, and NO2 Are Associated With Increased Proportions of Lower Airway Granulocytes in Ontario Horses. Ambient pollution is associated with the development and exacerbation of human asthma, but whether air pollution exposure is associated with lower airway inflammation in horses has not been fully evaluated. The Air Quality Health Index (AQHI) is an online tool used by asthmatic Ontarians to modify their outdoor activity when ambient pollution is high. A single AQHI value, falling on a scale from 1 to 10, is calculated from measurements of fine particulate matter (PM), nitrogen dioxide (NO), and ozone (O). Increased AQHI values predict an increased risk for presenting to a health care provider ...
Asymmetrical Pulmonary Cytokine Profiles Are Linked to Bronchoalveolar Lavage Fluid Cytology of Horses With Mild Airway Neutrophilia. Few data on cytokine profiles in bronchoalveolar lavage fluid (BALF) are available for racehorses with mild/moderate equine asthma (EA); cytological diagnosis being most frequently made from only one lung. The purpose of the study was to compare cytokine mRNA expressions and protein concentrations in BALF from both lungs. As part of a larger study, 250 ml saline was randomly instilled in one lung and 500 ml in the contralateral lung of 30 clinically healthy Standardbred racehorses. This procedure was repeated 72 h later, inversing the volume per lung. Cytological cut-off values for diagnosis o...
Effects of hypersensitivity disorders and environmental factors on the equine intestinal microbiota. Recent evidence suggests that an altered intestinal microbiota, specifically a reduction of bacterial diversity or a shift in microbial composition, is associated with the development of hypersensitivity disorders in humans, but this is unknown for horses. In this study we hypothesized that horses affected by either Culicoides hypersensitivity or severe equine asthma or both show a decreased diversity of their intestinal microbiota. We also investigated environmental effects. Rectal swab samples of a total of 140 horses were collected and the owners completed a detailed questionnaire about th...
Airway Diagnostics: Bronchoalveolar Lavage, Tracheal Wash, and Pleural Fluid. Indications for bronchoalveolar lavage, tracheal wash, and thoracocentesis for the diagnosis of respiratory diseases are discussed. Each technique is described in detail and illustrated by videos. Sample handling, preparation and evaluation are reviewed. The advantages and limitations of bronchoalveolar lavage and tracheal wash procedures as well as a critical comparison between the 2 techniques for equine asthma diagnosis are presented. Finally, validated cut-off values for equine asthma diagnosis are reviewed.
Fecal microbiota in horses with asthma. Gastrointestinal microbiota can be influenced by several factors, including diet and systemic inflammation, and in turn could act as a modulator of the allergic response. Fecal microbiota of horses with asthma has not been described. Objective: Analyze the bacterial fecal microbiota of horses with and without asthma under different environment and diet conditions, during both remission and exacerbation. Methods: Prospective observational study. Feces from 6 asthmatic and 6 healthy horses were collected under 3 different conditions: on pasture, housed indoors receiving good quality hay ("good h...
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...
Alveolar macrophage phenotypes in severe equine asthma. Because the alveolar macrophage (AM) phenotype of horses with severe equine asthma (SEA) is unknown, the cytokines expressed by M1- and M2-polarized AM were determined and the hypothesis that natural hay/straw challenge (NC) induces divergent AM phenotypes in control horses and horses with SEA was tested. Macrophages from control horses were activated either with eIFNγ + lipolysaccharide (LPS) or eIL-4 to characterize M1- or M2-polarized AM gene expression, respectively and determine the response of polarized cells to pathogen-associated molecular patterns (PAMPS): LPS, zymosan, peptidoglycan...
Tracheal microbial populations in horses with moderate asthma. There are limited data on potential dysbiosis of the airway microbiota in horses with asthma. Objective: We hypothesized that the respiratory microbiota of horses with moderate asthma is altered. Our objectives were (a) to quantify tracheal bacterial populations using culture and qPCR, (2) to compare aerobic culture and qPCR, and (c) to correlate bacterial populations with bronchoalveolar lavage fluid (BALF) cytology. Methods: Eighteen horses with moderate asthma from a hospital population and 10 controls. Methods: Prospective case-control study. Aerobic culture was performed on tracheal aspir...
Owner Compliance to an Environmental Management Protocol for Severe Equine Asthma Syndrome. Severe equine asthma (SEA) syndrome is a chronic recurrent respiratory disease, common among adult horses. The disease occurs in genetically susceptible individuals after their exposure to organic dust. Thus, environmental management has proved essential in controlling airway challenge and disease exacerbation. This is a demanding process that can only be achieved through the horse owners' cooperation. One year after initial diagnosis of SEA in a group of 39 horses, owner compliance to an environmental management protocol was evaluated. The overall compliance to the protocol was poor and the h...
Efficacy of dexamethasone, salbutamol, and reduced respirable particulate concentration on aerobic capacity in horses with smoke-induced mild asthma. Mild asthma in horses decreases racing performance and impairs gas exchange. The efficacy of treatment on performance is unknown. Objective: Treatment targeting lung inflammation improves V ˙ O2 peak in horses with mild asthma. Methods: Thoroughbred polo horses (n = 12) with smoke-induced mild asthma. Horses were exposed to increased ambient particulate matter (35.51 μg/m3 [PM2.5 ]; day mean, centrally measured) from day -33 to 0, from bushfire smoke (natural model). Methods: Prospective, randomized, placebo-controlled, double-blinded clinical trial. All horses completed 3 V ˙ O2 peak t...
Presence and function of β-adrenergic receptors in primary equine bronchial epithelia cells. The β-adrenergic receptor (β-AR) plays an important role in regulating a variety of cell and organ functions in different animal species and is an important target in asthma pathogenesis and therapy. The β-AR expression and function in equine bronchial epithelial cells (EBEC) were not known but innervation and significant decrease in receptor level were reported in the equine bronchial tissues from asthmatic horses. I-iodocyanopindolol (ICYP) binding studies were undertaken in primary freshly isolated and cultured EBEC to identify the presence of the β-ARs. The receptor distribution was as...
Prevalence and severity of ultrasonographic pulmonary findings in horses with asthma – a preliminary study. Asthma is one of the most common non-infectious respiratory diseases in horses. Ultrasound examination is a widely available non-invasive additional diagnostic tool. To date, there are no studies focusing on ultrasonographic findings in horses with asthma. The aim of this study was to analyse the prevalence and severity of ultrasound lesions in lung tissue in horses with asthma. Lung ultrasonography was carried out on six healthy horses (controls) and 12 horses with asthma (six with mild and six with severe asthma). The sonographic changes in three lung sections were assessed using a scoring s...
Science-in-brief: Latex in riding arenas and racetracks identified as a risk factor for equine respiratory health. This study investigates severe equine asthma (sEA), a significant health risk in horses similar to human asthma, identifying latex found in riding arenas and racetracks as a potential risk factor. […]
Effects of nebulized dexamethasone on the respiratory microbiota and mycobiota and relative equine herpesvirus-1, 2, 4, 5 in an equine model of asthma. Prolonged exposure to environmental antigens or allergens elicits an immune response in both healthy horses and those with mild asthma. Corticosteroids often are used to treat lower airway inflammation. Objective: To investigate the changes in equine herpesvirus (EHV)-1,2,4,5 glycoprotein B gene expression and changes in respiratory bacterial and fungal communities after nebulized dexamethasone treatment of horses with asthma. Methods: Horses with naturally occurring mild asthma (n = 16) and healthy control horses (n = 4). Methods: Prospective, randomized, controlled, blinded clinical trial. P...
Salivary Scavenger and Agglutinin (SALSA) Is Expressed in Mucosal Epithelial Cells and Decreased in Bronchial Epithelium of Asthmatic Horses. The Salivary Scavenger and Agglutinin (SALSA) protein is an innate immune protein with various alleged functions, including the regulation of inflammation and tissue remodeling. Transcriptomic studies of severe equine asthma (SEA) showed downregulation of the gene encoding SALSA in bronchial epithelium of asthmatic compared to non-asthmatic horses. This study aimed to characterize expression of SALSA in equine tissues by immunohistochemistry (IHC), corroborate potential differences in epithelial gene expression between asthmatic and non-asthmatic horses, and assess the structure of equine SALS...
Bronchoalveolar lavage fluid cytokine, cytology and IgE allergen in horses with equine asthma. The pathophysiology of equine asthma (EA) is still not fully described, but the involvement of an allergic reaction is strongly suspected. This theory has led to the use of allergen-specific immunoglobulin (Ig)E tests to support a diagnosis of asthma. The objective of this descriptive study was to evaluate the correlation between four subgroups of EA (mastocytic mild equine asthma [MEA], neutrophilic MEA, mixed MEA, and severe equine asthma [SEA]), allergen specific IgE (measured in both serum and BALF) and mRNA expression of selected genes in bronchoalveolar lavage fluid (BALF). Serum and BAL...
Equine bronchial fibroblasts enhance proliferation and differentiation of primary equine bronchial epithelial cells co-cultured under air-liquid interface. Interaction between epithelial cells and fibroblasts play a key role in wound repair and remodelling in the asthmatic airway epithelium. We present the establishment of a co-culture model using primary equine bronchial epithelial cells (EBECs) and equine bronchial fibroblasts (EBFs). EBFs at passage between 4 and 8 were seeded on the bottom of 24-well plates and treated with mitomycin C at 80% confluency. Then, freshly isolated (P0) or passaged (P1) EBECs were seeded on the upper surface of membrane inserts that had been placed inside the EBF-containing well plates and grown first under liquid...
The equine asthma model of airway remodeling: from a veterinary to a human perspective. Human asthma is a complex and heterogeneous disorder characterized by chronic inflammation, bronchospasm and airway remodeling. The latter is a major determinant of the structure-function relationship of the respiratory system and likely contributes to the progressive and accelerated decline in lung function observed in patients over time. Corticosteroids are the cornerstone of asthma treatment. While their action on inflammation and lung function is well characterized, their effect on remodeling remains largely unknown. An important hindrance to the study of airway remodeling as a major focu...
Effect of injected dexamethasone on relative cytokine mRNA expression in bronchoalveolar lavage fluid in horses with mild asthma. Mild equine asthma is a common inflammatory airway disease of the horse. The primary treatment of mild equine asthma is corticosteroids. The purpose of this study was to investigate the effects of injected dexamethasone on relative IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p35, IL-17, IL-23, IFN-γ, Eotaxin-2 and TNF-α mRNA expression in bronchoalveolar lavage (BAL) fluid in healthy Thoroughbred horses (n = 6), and those with mild equine asthma (n = 7). Results: Horses with mild equine asthma had a significantly greater bronchoalveolar lavage mast cell percentage than healthy horses...
Relaxing effects of clenbuterol, ritodrine, salbutamol and fenoterol on the contractions of horse isolated bronchi induced by different stimuli. β-adrenoceptor agonists are considered the most effective drugs to counteract bronchoconstriction in horses with asthma, but only clenbuterol is commonly employed in clinical practice. We evaluated the effects of different selective β agonists: clenbuterol, ritodrine, salbutamol, and fenoterol on the contractions of isolated bronchial muscle of horses induced by electrical field stimulation (EFS), carbachol, histamine, and KCl. All β agonists reduced the amplitude of contraction induced by the different stimuli but with variable efficacy and potency. Fenoterol and salbutamol were more effec...
Exercise Induced Laryngeal Obstruction in Humans and Equines. A Comparative Review. Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac diseas...
Antigen array for serological diagnosis and novel allergen identification in severe equine asthma. Severe equine asthma (sEA), which closely resembles human asthma, is a debilitating and performance-limiting allergic respiratory disorder which affects 14% of horses in the Northern Hemisphere and is associated with increased allergen-specific immunoglobulin E (IgE) against a range of environmental proteins. A comprehensive microarray platform was developed to enable the simultaneous detection of allergen-specific equine IgE in serum against a wide range of putative allergenic proteins. The microarray revealed a plethora of novel pollen, bacteria, mould and arthropod proteins significant in t...
Comparative Review of Asthma in Farmers and Horses. Farmers are routinely exposed to organic dusts and aeroallergens that can have adverse respiratory health effects including asthma. Horses are farm-reared large animals with similar exposures and can develop equine asthma syndrome (EAS). This review aims to compare the etiology, pathophysiology, and immunology of asthma in horses compared to farmers and highlights the horse as a potential translational animal model for organic dust-induced asthma in humans. Severe EAS shares many clinical and pathological features with various phenotypes of human asthma including allergic, non-allergic, late o...
Isolated airways in equine respiratory pharmacology: They never lie. Pre-clinical studies on human isolated bronchi have relevant translational value in human in vivo, conversely no investigation has been performed to assess whether data resulting from equine isolated airways can have any translational application in asthmatic horses. Thus, a meta-regression analysis via random-effect method was carried out to correlate the pharmacological characteristics of bronchodilators resulting from experiments performed in equine isolated bronchi with their impact on the lung function outcomes in asthmatic horses. Data on the potency of different bronchodilators were ext...
Development of a comprehensive protein microarray for immunoglobulin E profiling in horses with severe asthma. Severe asthma in horses, known as severe equine asthma (SEA), is a prevalent, performance-limiting disease associated with increased allergen-specific immunoglobulin E (IgE) against a range of environmental aeroallergens. Objective: To develop a protein microarray platform to profile IgE against a range of proven and novel environmental proteins in SEA-affected horses. Methods: Six SEA-affected and 6 clinically healthy Warmblood performance horses. Methods: Developed a protein microarray (n = 384) using protein extracts and purified proteins from a large number of families including pollen, ba...
MicroRNA-221 is overexpressed in the equine asthmatic airway smooth muscle and modulates smooth muscle cell proliferation. Airway wall remodeling, including hyperplasia and hypertrophy of smooth muscle (ASM) cells leading to an increased smooth muscle mass, is considered central to asthma. However, molecular pathways responsible for ASM remodeling remain poorly understood. MicroRNAs (miRNAs) have emerged as key regulators of inflammatory and repair processes affecting the lungs and can downregulate protein expression by inhibiting target mRNA translation. We therefore hypothesized that miRNAs are involved in ASM remodeling in asthma by modulating ASM proliferation. We have analyzed the expression of miRNAs in bron...
Randomised study of the immunomodulatory effects of azithromycin in severely asthmatic horses. Neutrophilic inflammation is believed to contribute to the airway obstruction and remodelling in equine asthma. Azithromycin, an antibiotic with immunomodulatory properties, reduces pulmonary neutrophilia and hyper-responsiveness in human asthmatics and decreases airway remodelling in rodent models of asthma. It was therefore hypothesised that azithromycin would improve lung function, mucus accumulation and central airway remodelling by decreasing luminal neutrophilia in severe equine asthma. The effects of a 10-day treatment with either azithromycin or ceftiofur, an antimicrobial without immu...