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Topic:Air Quality
Air quality refers to the presence and concentration of pollutants and particulates in the air that horses breathe. It encompasses a range of environmental factors, including dust, ammonia, mold spores, and other airborne contaminants commonly found in equine environments such as stables and arenas. Poor air quality can impact respiratory health in horses, leading to conditions such as recurrent airway obstruction (RAO) and inflammatory airway disease (IAD). This topic explores the sources and effects of air pollutants on equine respiratory systems and examines management practices aimed at improving air quality in equine facilities. This page compiles peer-reviewed research studies and scholarly articles that investigate the impact of air quality on horse health and performance.
Influence of horse stable environment on human airways. Many people spend considerable amount of time each day in equine stable environments either as employees in the care and training of horses or in leisure activity. However, there are few studies available on how the stable environment affects human airways. This study examined in one horse stable qualitative differences in indoor air during winter and late summer conditions and assessed whether air quality was associated with clinically detectable respiratory signs or alterations to selected biomarkers of inflammation and lung function in stable personnel. Methods: The horse stable environment...
Questionnaire assessment of airway disease symptoms in equine barn personnel. People working in cattle, swine and poultry barns have a higher prevalence of respiratory symptoms and decreased lung function. There is scant evidence regarding the respiratory health of humans working in horse barns, although it is well documented that stabled horses have a high prevalence of airway disease. Objective: To determine whether people spending time in horse barns have a higher prevalence of self-reported respiratory symptoms than non-exposed controls. Methods: A cross-sectional questionnaire study was conducted from May 2005 to January 2006 to investigate the prevalence of self-r...
Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristics. The necessary degree of arytenoid cartilage abduction (ACA) to restore airway patency at maximal exercise has not been determined. Objective: Use computational fluid dynamics modelling to measure the effects of different degrees of ACA on upper airway characteristics of horses during exercise. Objective: Maximal ACA by laryngoplasty is necessary to restore normal peak airflow and pressure in Thoroughbred racehorses with laryngeal hemiplegia. Methods: The upper airway was modeled with the left arytenoid in 3 different positions: maximal abduction; 88% cross-sectional area of the rima glottis; a...
Detection of virulent Rhodococcus equi in exhaled air samples from naturally infected foals. Virulent Rhodococcus equi causes pyogranulomatous bronchopneumonia in foals. The route of infection of foals has been considered to be inhalation of aerosolized bacteria from soil that is contaminated with equine feces. Thus, disease caused by R. equi has been regarded as an opportunistic infection of environmental origin and not a contagious disease. In this study, we report the exhalation of virulent R. equi from the respiratory tract of naturally infected foals. A handheld air-monitoring system was used to recover virulent R. equi from the exhaled breath of foals, and the concentration of v...
In vitro model for testing novel implants for equine laryngoplasty. To develop an in vitro laryngeal model to mimic airflow and pressures experienced by horses at maximal exercise with which to test laryngoplasty techniques. Methods: Randomized complete block. Methods: Cadaveric equine larynges (n=10). Methods: Equine larynges were collected at necropsy and a bilateral prosthetic laryngoplasty suture was placed with #5 Fiberwire suture to achieve bilateral maximal arytenoid abduction. Each larynx was positioned in a flow chamber and subjected to static flow and dynamic flow cycling at 2 Hz. Tracheal pressure and flow, and pressure within the flow chamber were ...
Markers of respiratory inflammation in horses in relation to seasonal changes in air quality in a conventional racing stable. Airborne factors in a conventionally managed racing stable and markers of pulmonary inflammation in the stabled horses were investigated on 3 occasions at 6-month intervals, including 2 winter periods and the intervening summer period. The stable measurements included inside and outside ambient temperature and relative humidity, levels of total and respirable dust, endotoxin, and 1,3-beta-glucan. Horses (n = 12) were examined in detail clinically as well as by endoscopy, bronchoalveolar lavage (BAL) cytology, and real-time polymerase chain reaction (RT-PCR) analysis of BAL-cells for IL-6 and I...
Endotoxin concentrations within the breathing zone of horses are higher in stables than on pasture. Inflammatory airway disease is common in stabled horses, with a prevalence of 17.3% in Michigan pleasure horses. Stable dust is rich in endotoxin, which may induce neutrophilic airway inflammation. Climatological conditions (ambient temperature and relative humidity) may influence endotoxin concentrations in pastures. The aim of this project was to determine if endotoxin levels in the breathing zone of horses in stables were higher than of horses on pasture, and if the endotoxin on pasture was associated with climatological conditions. Endotoxin exposure of six horses that were stabled or on p...
Mass scans from a proton transfer mass spectrometry analysis of air over Mediterranean shrubland browsed by horses. Plants usually emit large amount and varieties of volatiles after being damaged by herbivores. However, analytical methods for measuring herbivore-induced volatiles do not normally monitor the whole range of volatiles and the response to large herbivores such as large mammals is much less studied than the response to other herbivores such as insects. In this paper we present the results of using a highly sensitive proton transfer reaction-mass spectrometry (PTR-MS) technique that allows simultaneous monitoring of leaf volatiles in the pptv range. The resulting mass scans in air over Mediterran...
Detection of horse allergen around a stable. Integrating horse stables with built-up areas may lead to conflicts. Dispersion of horse allergen may become a health risk for allergic people. The aim was to measure the dispersion of horse allergen around a stable, considering wind speed and direction and vegetation. The disturbance of staff at a workplace nearby a stable was investigated. Methods: Air sampling was performed around a stable (32 horses) at distances of 50-500 m in all directions. Sampling was done with a pump and an IOM sampler. Samples were collected at 50 points during all seasons. Horse allergen levels were determined usin...
Lung function and airway cytologic profiles in horses with recurrent airway obstruction maintained in low-dust environments. The effects of long-term environmental management on airway obstruction and inflammation in horses with recurrent airway obstruction (RAO) are unknown. Objective: Horses with RAO maintained in low-dust environments have persistent airway obstruction and neutrophilic inflammation. Methods: Study horses were treated for RAO and then maintained in low-dust environments with no medical management. Horses were classified into 3 groups by years after diagnosis: 1 year (time 1, n = 9), 2-3 years (time 2, n = 7), and 5-6 years (time 3, n = 8). The comparison groups were age-matched healthy horses. Met...
Respirable dust concentrations in equine stables. Part 1: validation of equipment and effect of various management systems. Traditional methods of measuring airborne dust concentrations (ADC) in animal housing have included the collection of dust onto pre-weighed filters permitting the calculation of mean, not maximum, ADC. However real-time continuous particle monitors are advantageous in identifying short duration elevations in ADC which may be detrimental to equine respiratory health in the face of a relatively low mean ADC. These monitors have not previously been used to measure ADC in equine stables. Comparisons of a filter-based sampler and a real-time continuous particle monitor revealed no significant diffe...
Respirable dust concentrations in equine stables. Part 2: the benefits of soaking hay and optimising the environment in a neighbouring stable. The effect of soaking hay to minimise equine breathing zone respirable dust concentration (RDC) is unknown, as is the duration of soaking required. Additionally, the influence of the bedding and forage used in one stable on the mean and maximum RDC in a neighbouring stable within a common airspace is unknown. Consequently, in the management of equine environmental respiratory disease uncertainty remains about the necessity for optimising conditions in neighbouring stables. Investigations using a real-time continuous particle monitor revealed that when feeding hay, horses' mean breathing zone R...
Suitability of biocompost as a bedding material for stabled horses: respiratory hygiene and management practicalities. Bedding material in stables has an important influence on air hygiene and information on the suitability of biocompost and wood shavings is incomplete. Objective: To compare the suitability and benefit of biocompost and wood shavings as bedding in horse stables and to determine key air factors for the evaluation of the potential impact of these materials on respiratory health. Methods: The study was conducted in a naturally ventilated stable with 4 horses. Air hygiene parameters were measured 24 h/day for 7 days with each bedding type: ammonia (NH3), inhalable and respirable dust, endotoxins, ...
Elevated amount of Toll-like receptor 4 mRNA in bronchial epithelial cells is associated with airway inflammation in horses with recurrent airway obstruction. Recurrent airway obstruction (RAO) is characterized by neutrophilic airway inflammation and obstruction, and stabling of susceptible horses triggers acute disease exacerbations. Stable dust is rich in endotoxin, which is recognized by Toll-like receptor (TLR) 4. In human bronchial epithelium, TLR4 stimulation leads to elevation of interleukin (IL)-8 mRNA expression. The zinc finger protein A20 negatively regulates this pathway. We hypothesized that TLR4 and IL-8 mRNA and neutrophil numbers are elevated and that A20 mRNA is not increased in RAOs during stabling compared with controls and with R...
Early onset airway obstruction in response to organic dust in the horse. Equine recurrent airway obstruction (RAO) has been used as a naturally occurring model of human asthma. However, it is unknown whether there is an early-phase response in RAO. The aim of this study was to determine whether exposure to organic dust induces immediate changes in lung function in RAO-affected horses, which could be mediated by airway mast cells. Six RAO-affected horses in remission and six control horses were challenged with hay-straw dust suspension by nebulization. Total respiratory resistance at 1 Hz, measured by forced oscillation, was increased from 0.62 +/- 0.09 cmH(2)O.l(-1...
A comparison of total, respirable, and real-time airborne particulate sampling in horse barns. Measurements of total, respirable, and real-time airborne particulate were obtained in 12 horse barns in summer and winter. Respirable and total particulate concentrations were measured gravimetrically; real-time particulate was measured with an aerosol photometer. Total particulate (TP) ranged from nondetectable (ND) to 2.1 mg/m3 and from ND to 1.2 mg/m3 for winter and summer sampling, respectively. Respirable particulate (RP) ranged from ND to 0.2 mg/m3 and from ND to 0.7 mg/m3 for winter and summer measurements, respectively. The mean respirable fraction of particulate for summer and winter...
Associations between the ecology of virulent Rhodococcus equi and the epidemiology of R. equi pneumonia on Australian thoroughbred farms. The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associate...
Comparison of concentrations of Rhodococcus equi and virulent R. equi in air of stables and paddocks on horse breeding farms in a temperate climate. Rhodococcoccus equi is a significant cause of bronchopneumonia in foals worldwide. Infection of the lungs is believed to result from inhalation of virulent R. equi in dust from contaminated environments. A measure of infectious risk in an environment is the level of airborne contamination. Objective: To assess and compare the level of airborne virulent R. equi in paddocks and stables. Methods: Air samples were collected sequentially over the 2003 foaling season from the paddocks and stables on 3 Irish horse breeding farms affected by R. equi pneumonia. Colony blotting and DNA hybridisation tec...
Effects of changes to the stable environment on the exhalation of ethane, carbon monoxide and hydrogen peroxide by horses with respiratory inflammation. The aim of this study was to assess the effects of changes to the stable environment on exhaled markers of respiratory inflammation in six horses with clinical histories of recurrent airway obstruction. The horses were maintained for two weeks under conventional stable management (straw bedding and hay) and for two weeks on a reduced-dust regimen (paper bedding and ensiled grass), in a crossover study design. Exhaled ethane and carbon monoxide (CO) and exhaled breath condensate hydrogen peroxide (H(2)O(2)) were measured every three days under each regimen. The presence of clinical signs of air...
Effect of composition and different fractions of hay dust suspension on inflammation in lungs of heaves-affected horses: MMP-9 and MMP-2 as indicators of tissue destruction. Airway matrix metalloproteinases (MMPs) increase following inhalation of organic dust. The relative contribution of dust components to this elevation is unknown. Objective: To identify components of organic dust responsible for elevated MMP levels in equine airways. Methods: Bronchoalveolar lavage (BALF) from 7 heaves-susceptible horses, collected 6 h following inhalation challenges with saline, 2 different hay dust suspensions (HDS-1 and -2) and soluble and particulate fractions of HDS-1, were analysed for MMP-2 and -9 using SDS-page gelatin zymography. Results: HDS-1 challenge increased BALF...
Identification and seasonal distribution of airborne fungi in three horse stables in Italy. Fungal agents are responsible for a variety of respiratory diseases both in humans and animals. The nature and seasonal variations of fungi have been investigated in many environments with wide ranging results. The aims of the present report were (i) to evaluate the quality and magnitude of exposure to airborne fungi in three differently structured equine stalls (open air, partially and completely enclosed buildings) during a one-year period, using an air sampling technique and (ii) to compare the distribution and frequency of fungal species, with regards to these different environments. Air s...
Variety in dustiness and hygiene quality of peat bedding. Respiratory exposure to organic dust induces chronic pulmonary diseases both in farmers and horses. The aim of this study was to examine the variation of dustiness and hygiene quality of peat moss bedding. Materials studied were weakly decomposed sphagnum peat (A), weakly decomposed sphagnum peat warmed up in storage (> 30 degrees C) (B) and two more decomposed few-flowered sedge peats (C and D). The geometric mean of mesophilic fungi, thermotolerant fungi and thermophilic actinomycetes were determined from the material. Samples of inhalable dust and endotoxins were collected with IOM sampl...
Climatic and aeroallergen risk factors for chronic obstructive pulmonary disease in horses. To estimate the association between climate and airborne pollen and fungal factors and chronic obstructive pulmonary disease (COPD) in horses. Methods: Data from 1,444 horses with a diagnosis of COPD. Methods: The Veterinary Medical Database was used to identify records of horses admitted to veterinary teaching hospitals in the United States and Canada between 1990 and 1999. Rainfall, mean minimum and maximum temperature, and maximum monthly pollen and fungal spore (mold) counts recorded at the city closest to where the hospital is located were identified for each month data were reported to t...
Antioxidant and inflammatory responses of healthy horses and horses affected by recurrent airway obstruction to inhaled ozone. Inhaled ozone can induce oxidative injury and airway inflammation. Horses affected by recurrent airway obstruction (RAO) have a decreased pulmonary antioxidant capacity, which may render them more susceptible to oxidative challenge. It is currently unknown whether RAO-affected horses are more susceptible to oxidative stress than those unaffected by RAO. Objective: To determine whether ozone exposure induces greater oxidative stress and airway inflammation in RAO-affected horses in remission than in healthy horses. Methods: Seven healthy control horses and 7 RAO-affected horses were exposed to ...
Dose responses to inhalation of endotoxin, hay dust suspension and Aspergillus fumigatus extract in horses as measured by levels and activation of matrix metalloproteinase-9. Airway matrix metalloproteinases (MMPs) increase after endotoxin (LPS) exposure, but there are no reports describing dose-dependent increases or activation following exposure. Objective: To study matrix metalloproteinase-9 (MMP-9) and -2 (MMP-2) responses in bronchoalveolar lavage fluid (BALF) from heaves-susceptible and control horses following inhalation of hay dust suspension (HDS), LPS and Aspergillus fumigatus extract (AFE). Methods: Heaves-susceptible (n = 7) and control (n = 6) horses received inhalation challenges with 3 different doses of HDS and LPS. Heaves-susceptible horses (n = 6)...
Assessment of electrical charge on airborne microorganisms by a new bioaerosol sampling method. Bioaerosol sampling is necessary to monitor and control human exposure to harmful airborne microorganisms. An important parameter affecting the collection of airborne microorganisms is the electrical charge on the microorganisms. Using a new design of an electrostatic precipitator (ESP) for bioaerosol sampling, the polarity and relative strength of the electrical charges on airborne microorganisms were determined in several laboratory and field environments by measuring the overall physical collection efficiency and the biological collection efficiency at specific precipitation voltages and po...
Airway mucus in recurrent airway obstruction–short-term response to environmental challenge. Mucus accumulation and neutrophilic inflammation in the airways are hallmarks of heaves. Endoscopically visible mucus accumulations, however, have not been studied during exposure to dusty hay and allergens (ie, environmental challenge). We hypothesized that (1) heaves-affected horses have increased mucus accumulation compared with controls, (2) mucus accumulations increase in heaves-affected horses during environmental challenge, and (3) environmental challenge also induces neutrophilic inflammation and mucus accumulation in control horses. Mucus accumulation was graded endoscopically (mucus ...
Airway inflammation and mucus in two age groups of asymptomatic well-performing sport horses. Horses housed in conventional stable environments are exposed to high dust loads. Long-term exposure to inhaled dust may lead to subclinical airway disease. Objective: Airway inflammation and mucus accumulation are 1) common in asymptomatic well-performing sport horses, 2) increased in older compared to younger individuals and 3) correlated. Methods: Mucus quantity and quality (endoscopic scoring) and BALF differential cytology were assessed in 13 younger horses (mean age 5 years) and 13 older horses (mean age 15 years), which had no historical or clinical evidence of lower airway disease, wer...
Inhaled endotoxin and organic dust particulates have synergistic proinflammatory effects in equine heaves (organic dust-induced asthma). Equine heaves is a naturally occurring organic dust-induced asthma characterized by airway neutrophilia, mucus hypersecretion and obstructive lung dysfunction. However, the relative role of different dust components in disease severity remains unclear. Objective: This study investigated the relative contribution of inhaled endotoxin and organic dust particulates (mainly mould spores) in inducing heaves in heaves-susceptible horses. Methods: Control and heaves-susceptible horses received inhalation challenges with hay dust suspension (HDS) before and after lipopolysaccharide (LPS) depletion. He...
