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.
Nebulisation of dexamethasone sodium phosphate for the treatment of severe asthmatic horses. Inhaled corticosteroids are effective in the treatment of equine asthma. A recent study reported that nebulisation of injectable dexamethasone had low systemic bioavailability in healthy horses and could represent a cost-effective therapy for equine inflammatory lung diseases. Objective: To determine the effects of dexamethasone nebulisation on lung function in severe asthmatic horses. It was hypothesised that dexamethasone administered by nebulisation would be more effective than the same dose administered orally. Methods: Randomised blinded experimental study in severe asthmatic horses. Meth...
Pollens destroy respiratory epithelial cell anchors and drive alphaherpesvirus infection. Pollens are well-known triggers of respiratory allergies and asthma. The pollen burden in today's ambient air is constantly increasing due to rising climate change and air pollution. How pollens interact with the respiratory mucosa remains largely unknown due to a lack of representative model systems. We here demonstrate how pollen proteases of Kentucky bluegrass, white birch and hazel selectively destroy integrity and anchorage of columnar respiratory epithelial cells, but not of basal cells, in both ex vivo respiratory mucosal explants and in vitro primary equine respiratory epithelial cells...
Bronchoalveolar Lavage Cytology Characteristics and Seasonal Changes in a Herd of Pastured Teaching Horses. Equine asthma syndrome (EAS) is a common problem that affects horses of any age. Severe EAS is reported to affect 10-20% of adult horses in the northern hemisphere, while mild/moderate EAS is reported to affect 60-100% of adult horses, depending on the population and geographic region. For both severe and mild/moderate EAS, the presence of lower airway inflammation is attributed to airborne "triggers" such as dust, mold, and bacterial components that horses encounter in hay and stable-environments; and treatment recommendations for horses with EAS often include full-time pasture turnout. The c...
Evaluation of lipid markers in surfactant obtained from asthmatic horses exposed to hay. OBJECTIVE To evaluate the lipidomic profile of surfactant obtained from horses with asthma at various clinical stages and to compare results with findings for healthy horses exposed to the same conditions. SAMPLE Surfactant samples obtained from 6 horses with severe asthma and 7 healthy horses. PROCEDURES Clinical evaluation of horses and surfactant analysis were performed. Samples obtained from horses with severe asthma and healthy horses before (baseline), during, and after exposure to hay were analyzed. Crude surfactant pellets were dried prior to dissolution in a solution of isopropanol:me...
The effect of single pretreatment with salbutamol on recovery of bronchoalveolar lavage fluid in horses with suspected or confirmed severe equine asthma. Bronchoalveolar lavage (BAL) is a method for the recovery of respiratory secretion from the lower airways. Objective: To investigate if the administration of a single dose of a bronchodilatator in horses with a suspected or confirmed severe equine asthma could improve recovery of bronchoalveolar lavage fluid (BALF). Methods: Twenty-eight horses with severe equine asthma. Methods: Horses were divided into 2 groups: group "treated" was given salbutamol before endoscopic examination and BALF collection, whereas group "not treated" was not given. BAL was performed with BAL-catheter by instilling 3...
Are Respiratory Clinical Signs in Horses Associated With Strongyle Egg Shedding Rates on Farms With Varying Egg Shedding Levels? Respiratory signs or more specifically severe equine asthma (SEA) is in some studies reported to be associated with decreased strongyle egg shedding. This association can be reproduced in a larger population of unrelated horses. The owners of 209 horses, on seven farms in Bavaria, were interviewed using, an in prior studies validated questionnaire. Horses were categorized into classes of the horse owner assessed respiratory signs index (HOARSI 1-4, unaffected to severely affected). In total, 1,035 fecal samples were analyzed between March 2011 and September 2014 using a modified McMaster proce...
The Effect of Race Training on the Basal Gene Expression of Alveolar Macrophages Derived From Standardbred Racehorses. Mild-to-moderate equine asthma is prevalent in young racehorses, particularly early in their training period. Although the precise etiopathogenesis remains undetermined, it is possible that the susceptibility of this population might partly reflect an exercise-associated immune derangement at the level of the airway. We performed a genome-wide basal gene expression scan on alveolar macrophages (AMs) isolated from Standardbred racehorses before and after commencement of competition race training with a view to identifying any exercise-associated gene expression modulation consistent with functi...
Fungi in respiratory samples of horses with inflammatory airway disease. Fungi contribute to the inflammatory response of lungs in horses with recurrent airway obstruction and in some forms of asthma in humans. The role of fungi in inflammatory airway disease (IAD) has not been assessed. Objective: Evaluate the prevalence of fungi in the respiratory samples of horses diagnosed with IAD, describe clinical signs associated with the presence of fungi in respiratory samples, and assess the risk factors associated with IAD and with the presence of fungi in the airways. Methods: Seven-hundred thirty-one active horses referred to a specialized ambulatory practice for sign...
Contribution of lung function tests to the staging of severe equine asthma syndrome in the field. Staging methods are useful tools for monitoring disease and response to treatment, and because Severe Equine Asthma Syndrome (SEAS) has a high prevalence in the equine population, a clinical staging method can provide important information to optimize equine care. Our team has previously developed and published a clinical staging method for SEAS and in the present study we further evaluated information provided by lung function tests, in order to determine their contribution to disease staging. Using discriminant analysis we set out to produce a new staging method with applicability in the fie...
Adherence to treatment recommendations and short-term outcome of pleasure and sport horses with equine asthma. Treatments for mild forms of equine asthma are extrapolated from those recommended for severe equine asthma (heaves), but little is known about owner's adherence to recommendations and treatment efficacy. The objective was to determine which recommendations are implemented by owners and their perception of the clinical response to treatment. Medical records of 43 horses diagnosed with moderate asthma between 2010 and 2012 were retrieved from the Université de Montréal database. Treatments and perceived responses were recorded by telephone survey, 2 to 35 months after diagnosis. All 33 owners...
Bronchoalveolar lavage fluid from both lungs in horses: Diagnostic reliability of cytology from pooled samples. Cytology of bronchoalveolar lavage fluid (BALF) from one lung may not predict findings in the contralateral lung of the same horse. The aim of this study was to determine whether a pooled BALF from both lungs was representative of corresponding individual samples. Fifty-one horses referred for poor performance and/or respiratory signs and for which a BALF was collected from both lungs, were included in the study. Cytology of pooled and individual BALF samples were performed using a masked protocol. Based on clinical signs and individual BALF cytologies, horses were classified as control (CTL),...
Allergen-specific immunoglobulin E in sera of horses affected with insect bite hypersensitivity, severe equine asthma or both conditions. Genetic, epidemiologic, and clinical evidence suggests that, in horses, there are manifestations of hypersensitivity that can occur together. Objective: To investigate whether concurrent insect bite hypersensitivity (IBH) and severe equine asthma (EA) is associated with higher allergen-specific and total serum immunoglobulin E (IgE) concentrations than only EA or IBH. Methods: Healthy control horses (C, n = 40), horses with IBH (IBH, n = 24), severe EA (EA, n = 18), and both conditions (IBH/EA, n = 23) were included. Methods: In our retrospective comparative study, sera from ho...
The influence of hay steaming on clinical signs and airway immune response in severe asthmatic horses. Avoidance of antigenic stimuli was found to significantly reverse airway obstruction of horses with severe equine asthma (sEA). To date, no published study investigated the influence of steaming hay on lower airway condition of sEA-affected horses. The objectives were to determine the clinical, cytological and cytokine respiratory responses of both sEA and control (CTL) horses experimentally exposed to steamed or dry hay. Results: A cohort of 6 sEA horses and 6 CTL horses was involved in this field study. On day 0, both groups were fed with steamed hay for 5 consecutive days, followed by a was...
Equine lung decellularization: a potential approach for in vitro modeling the role of the extracellular matrix in asthma. Contrary to conventional research animals, horses naturally develop asthma, a disease in which the extracellular matrix of the lung plays a significant role. Hence, the horse lung extracellular matrix appears to be an ideal candidate model for in vitro studying the mechanisms and potential treatments for asthma. However, so far, such model to study cell-extracellular matrix interactions in asthma has not been developed. The aim of this study was to establish a protocol for equine lung decellularization that maintains the architecture of the extracellular matrix and could be used in the future ...
Gene set enrichment analysis of the bronchial epithelium implicates contribution of cell cycle and tissue repair processes in equine asthma. Severe equine asthma is a chronic inflammatory condition of the lower airways similar to adult-onset asthma in humans. Exacerbations are characterized by bronchial and bronchiolar neutrophilic inflammation, mucus hypersecretion and airway constriction. In this study we analyzed the gene expression response of the bronchial epithelium within groups of asthmatic and non-asthmatic animals following exposure to a dusty hay challenge. After challenge we identified 2341 and 120 differentially expressed genes in asthmatic and non-asthmatic horses, respectively. Gene set enrichment analysis of changes...
SRSF6 is upregulated in asthmatic horses and involved in the MYH11 SMB expression. Smooth muscle has a central role in bronchospasm-induced airway obstruction in asthma. Alternative mRNA splicing of the smooth muscle myosin heavy chain (myh11) gene produces four different isoforms, one of which (SMB) is characterized by the inclusion of the exon5b, which doubles the smooth muscle cells contraction velocity. Deciphering the regulation of the expression levels of the SMB isoform would represent a major step for the understanding of the triggers and pathways leading to airway smooth muscle contraction in asthma. Our objective was therefore, to study the splicing regulation mech...
Tamoxifen inhibits chemokinesis in equine neutrophils. Neutrophils are terminally differentiated innate effector cells at the first line of host defense. Neutrophil migration within tissues is complex and involves several steps, during which these cells must be able to interpret a variety of chemical and physical signals. Exacerbated neutrophil activity can be harmful to surrounding tissues; this is important in a range of diseases, including equine asthma. Tamoxifen (TX) is a non-steroidal estrogen receptor modulator with effects on cell growth and survival. Previous studies showed that TX treatment in horses with induced acute pulmonary inflamma...
Sequence variant analysis of RNA sequences in severe equine asthma. Severe equine asthma is a chronic inflammatory disease of the lung in horses similar to low-Th2 late-onset asthma in humans. This study aimed to determine the utility of RNA-Seq to call gene sequence variants, and to identify sequence variants of potential relevance to the pathogenesis of asthma. Methods: RNA-Seq data were generated from endobronchial biopsies collected from six asthmatic and seven non-asthmatic horses before and after challenge (26 samples total). Sequences were aligned to the equine genome with Spliced Transcripts Alignment to Reference software. Read preparation for sequenc...
Equine asthma: Integrative biologic relevance of a recently proposed nomenclature. The term "equine asthma" has been proposed as a unifying descriptor of inflammatory airway disease (IAD), recurrent airway obstruction (RAO), and summer pasture-associated obstructive airway disease. Whilst the term will increase comprehensibility for both the lay and scientific communities, its biologic relevance must be compared and contrasted to asthma in human medicine, recognizing the limited availability of peer-reviewed equine-derived data, which are largely restricted to clinical signs, measures of airway obstruction and inflammation and response to therapy. Such limitations constrain ...
Metabolomics of tracheal wash samples and exhaled breath condensates in healthy horses and horses affected by equine asthma. The present work characterized the metabolomic profile of tracheal wash (TW) and exhaled breath condensate (EBC) in healthy horses and horses with respiratory disease. Six asthma-affected horses (group A) and six healthy controls (group H) underwent clinical, endoscopic and cytologic examinations of upper airways to confirm the active phase of asthma. TW and EBC samples were collected from each animal and investigated by proton nuclear magnetic resonance (H-NMR) metabolomic analysis. A total of ten out of 38 metabolites found in the TW were significantly different between the groups (p < ...
Efficacy of inhaled budesonide for the treatment of severe equine asthma. Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs. Objective: To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma. Methods: Experimental studies in horses with naturally occurring asthma with cross-over, randomised, blinded experimental designs. Methods: In Study 1, budeson...
An observational study of environmental exposures, airway cytology, and performance in racing thoroughbreds. Mild equine asthma is presumed to arise in response to environmental exposures but the relative impact of differing inflammatory phenotypes upon performance are largely unexplored. Objective: Airway inflammation negatively affects performance and cytological phenotype varies with environmental exposure. Methods: Thoroughbred racehorses in active training and racing. Methods: Thoroughbreds were recruited 24-48 hours before racing. Each horse was eligible for re-enrollment with each race entry. Within one hour of race completion, physical examination, respiratory endoscopy, and BAL were performe...
Companion animals and human health: benefits, challenges, and the road ahead for human-animal interaction. There is ample evidence that human-animal interaction (HAI) is associated with health. Studies encompass three general categories: those that compare companion animal owners with individuals who do not own companion animals, those examining brief, 'one-off' contacts with animals, and those that review animal-assisted interventions. The health benefits demonstrated typically include reductions in depression and loneliness, while enhancing social interaction or social skills, and decreasing anxiety and arousal. Other health benefits associated with companion animals include the promotion of exer...
Lung Microbiome Is Influenced by the Environment and Asthmatic Status in an Equine Model of Asthma. There is evidence that the lung microbiome differs between patients with asthma and healthy humans, but the effect of environmental conditions and medication is unknown and difficult to study. Equine asthma is a naturally occurring chronic airway disease characterized by reversible airway inflammation and bronchoconstriction upon exposure to inhaled antigens. In the present study, we evaluated the effect that environmental conditions and disease status have on pulmonary, nasal, and oral microbiomes. Six asthmatic and six healthy horses were studied while at pasture ("low antigen exposure"), as...
Bronchoalveolar lavage fluid cytology and airway hyper-reactivity in clinically normal horses. To characterise the relationship between bronchoalveolar lavage fluid (BALF) cytology and pulmonary function testing with histamine bronchoprovocation (HBP) methods in a population of clinically normal horses. Methods: Cross-sectional study METHODS: Clinically normal adult horses (n = 33) underwent pulmonary function testing and HBP with a commercial flowmetric plethysmography system. BAL was performed 1-5 days later. Statistical analysis was used to assess associations between BALF cell concentration, relative inflammatory cell percentages and categorisation, and airway hyper-reactivity...
Effects of magnesium sulfate infusion on clinical signs and lung function of horses with severe asthma. OBJECTIVE To evaluate whether MgSO solution administered IV would improve the clinical signs and lung function of horses with severe asthma and potentiate the effects of salbutamol inhalation in those horses. ANIMALS 6 adult horses with severe asthma. PROCEDURES Asthmatic horses were used in 3 crossover design experiments (6 treatments/horse). Clinical scores for nasal flaring and the abdominal component associated with breathing and lung function were determined before and after administration of salbutamol (800 μg, by inhalation), MgSO solution (2.2 mg/kg/min, IV, over 20 minutes), and comb...
Efficacy of tamoxifen for the treatment of severe equine asthma. Tamoxifen, a selective estrogen receptor modulator, decreased airway neutrophilia and improved clinical signs in an experimental model of equine asthma, and induced neutrophilic apoptosis in vitro. Objective: Tamoxifen reduces airway neutrophilia and improves lung function in severe asthmatic horses. Methods: Twelve severe asthmatic horses from a research herd. Methods: Randomized controlled blinded study design. The effects of a 12-day oral treatment with tamoxifen (0.22 mg/kg, q24h) or dexamethasone (0.06 mg/kg, q24h) on lung function, endoscopic tracheal mucus score and bronchoalveolar ...
eQTL discovery and their association with severe equine asthma in European Warmblood horses. Severe equine asthma, also known as recurrent airway obstruction (RAO), is a debilitating, performance limiting, obstructive respiratory condition in horses that is phenotypically similar to human asthma. Past genome wide association studies (GWAS) have not discovered coding variants associated with RAO, leading to the hypothesis that causative variant(s) underlying the signals are likely non-coding, regulatory variant(s). Regions of the genome containing variants that influence the number of expressed RNA molecules are expression quantitative trait loci (eQTLs). Variation associated with RAO ...
Does antimicrobial therapy improve outcomes in horses with severe equine asthma and a positive tracheal wash bacterial culture? The objective of this study was to observe the outcomes of adding an antimicrobial treatment to a conventional treatment regime in horses with severe equine asthma in a clinical setting. Eleven client-owned horses with a history consistent with severe equine asthma, increased respiratory effort and nostril flaring, ≥ 20% neutrophils on bronchoalveolar lavage (BAL), and a positive tracheal wash (TW) bacterial culture were treated with environmental management, corticosteroids, and bronchodilators. Six horses were also treated with an antimicrobial (principal group), while the other 5 were adm...