Topic:Bronchodilation
Bronchodilation refers to the physiological process of widening the air passages in the lungs, facilitated by the relaxation of bronchial smooth muscle. In horses, bronchodilation is significant due to its impact on respiratory efficiency and its relevance in managing equine respiratory conditions such as heaves (recurrent airway obstruction) and inflammatory airway disease. Various pharmacological agents, including beta-agonists and anticholinergics, are employed to induce bronchodilation in horses, aiding in the alleviation of airway obstruction and improvement of airflow. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, therapeutic applications, and effects of bronchodilation in equine respiratory health.
Comparative study of the bronchodilator efficacy and adverse effects of salbutamol and hyoscine butylbromide in horses with severe asthma. Salbutamol and hyoscine butylbromide (HBB) are commonly used bronchodilators in horses with severe asthma (SA). Objective: To compare the bronchodilation potency, duration, and adverse effects of salbutamol and HBB in SA. Methods: Six horses in exacerbation of SA. Methods: The effects of inhaled salbutamol (1000 μg) and HBB (150 mg, IV) were compared in a randomized, blinded, crossover experiment. Lung function, intestinal borborygmi and heart rate were assessed before and sequentially until 180 minutes after drug administration, and analyzed with 2-way repeated-measures ANOVA and Dunne...
Respiratory oscillometry testing in relation to exercise in healthy and asthmatic Thoroughbreds. Racehorses may experience exercise-induced bronchodilation or bronchoconstriction, with potential differences between healthy and asthmatic individuals. Objective: To identify exercise-related lung function variations by oscillometry in racehorses, compare lung function between healthy and mild equine asthma (MEA) horses, assess oscillometry's potential as a predictor of racing fitness. Methods: Prospective case-control clinical study. Methods: Fourteen Thoroughbred racehorses (5 healthy, 9 MEA) underwent a protocol including respiratory oscillometry at rest, exercise with fitness monitoring, ...
Effect of Clenbuterol on Muscle Activity During Exercise in Standardbred Horses. Clenbuterol (β agonist) is a commonly administered bronchodilator in race and performance horses. While long-term administration can alter exercise performance and muscle properties, little is known about its effects on these parameters following short-term administration. A single dose of clenbuterol (0.80 µg/kg) was expected to alter muscle activity of the extensor carpi radialis, semitendinosus, and longissimus dorsi during submaximal exercise. Eight mature Standardbred horses exercised for 2 minutes at 5 m/s on a high-speed treadmill following clenbuterol dosing (clenbuterol) or no dosin...
The Effect of Inhaled Albuterol on PaO2 in Anesthetized Horses Receiving a FiO2 of 0.5 or >0.95. Impairment of oxygen uptake can occur during general anesthesia in horses resulting in hypoxemia. Multiple treatments have been investigated for correction of hypoxemia with varying levels of success. In clinical trials, albuterol, a short-acting β2 adrenergic agonist, improved arterial oxygen partial pressure (PaO2) in anesthetized horses unresponsive to adjustments in mechanical ventilation and administration of positive inotropic drugs. However, controlled studies comparing the magnitude of change and duration of effect of albuterol on PaO2 in healthy, nonhypoxemic anesthetized horses are ...
[Remodeling in equine asthma - Effects of antigen avoidance and pharmacological therapy]. The term remodeling describes the process resulting in a tissue that is structurally and architecturally altered compared to its healthy counterpart. At least in severe equine asthma, this occurs mainly, but not exclusively, as a consequence of neutrophilic airway inflammation and is characterized by hypertrophy of the smooth muscle layers in airway and arterial walls as well as fibrosis of the bronchial walls and pulmonary interstitial tissue. To date, much less is known for mild to moderate equine asthma. For a long time it was assumed that these processes are irreversible, and at least for ...
Can bronchoconstriction and bronchodilatation in horses be detected using electrical impedance tomography? Electrical impedance tomography (EIT) generates images of the lungs based on impedance change and was able to detect changes in airflow after histamine challenge in horses. Objective: To confirm that EIT can detect histamine-provoked changes in airflow and subsequent drug-induced bronchodilatation. Novel EIT flow variables were developed and examined for changes in airflow. Methods: Bronchoconstriction was induced using stepwise histamine bronchoprovocation in 17 healthy sedated horses. The EIT variables were recorded at baseline, after saline nebulization (control), at the histamine concentra...
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...
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...
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...
Clinical efficacy of bronchodilators in equine asthma: Looking for minimal important difference. Airway obstruction is the main trait of severe equine asthma that affects respiratory function and elicits detrimental effects on clinical presentation. Only few and underpowered clinical studies have investigated the impact of improvement in lung function induced by bronchodilators on the clinical signs of asthma-affected horses. Objective: To identify the minimal important difference (MID) in lung function elicited by bronchodilator leading to a meaningful improvement in clinical signs. Methods: Pairwise meta-analysis and meta-regression analysis. Methods: Literature searches were performed ...
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...
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...
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...
Combining long-acting bronchodilators with different mechanisms of action: A pharmacological approach to optimize bronchodilation of equine airways. The ultra long-acting β -adrenoceptor agonist olodaterol plus the ultra long-acting muscarinic antagonist tiotropium bromide are known to relax equine airways. In human bronchi combining these drugs elicits a positive interaction, thus we aimed to characterize this information further in equine isolated airways stimulated by electrical field stimulation (EFS) and using the Concentration-Reduction Index (CRI) and Combination Index (CI) equations. The drugs were administered alone and together by reproducing ex vivo the concentration-ratio delivered by the currently available fixed-dose combina...
Use of Nasotracheal Intubation during General Anesthesia in Two Ponies with Tracheal Collapse. Ponies with tracheal collapse may have an increased anesthetic risk due to airway obstruction during induction and recovery. To our knowledge, there are no anesthetic descriptions of these patients, despite a reported 5.6% incidence and 77% mortality rate. Two Shetland ponies with tracheal collapse, a 12-year-old male (pony 1) and a 27-year-old female (pony 2), were referred for right eye enucleation due to a perforating corneal ulcer and severe recurrent uveitis, respectively. Pony 1 was stressed, had lung stridor and hyperthermia, and developed inspiratory dyspnea with handling. Radiography ...
Effects of selective α2 -adrenergic receptor agonists on electrical field-stimulated contractions of isolated bronchi in horses. We investigated the effects of different selective α -adrenergic receptor (AR) agonists (detomidine, medetomidine, xylazine, and brimonidine) on the contractions of horse-isolated bronchi induced by electrical field stimulation (EFS) and by carbachol. No effects were observed on the contraction induced by carbachol, while α -AR agonists reduced EFS-evoked contractions in a concentration-related fashion. The rank order of potency (pD ) was brimonidine (7.40 ± 0.20) >medetomidine (7.09 ± 0.24) >detomidine (6.13 ± 0.55) >xylazine (4.59 ± 0.16). The maximal effects (E ) were -56.3% ...
Pharmacological characterization of the interaction between tiotropium and olodaterol administered at 5:5 concentration-ratio in equine bronchi. Equine airways represent a suitable ex vivo model to study the functional impact of pharmacological treatments on human chronic obstructive pulmonary disorders, such as asthma and chronic obstructive pulmonary disease (COPD). We aimed to characterize the pharmacological interaction between the long-acting muscarinic antagonist (LAMA) tiotropium and the long-acting β-agonist (LABA) olodaterol in equine airways. The effect of tiotropium and olodaterol, administered alone and in combination at the ratio of concentrations reproducing ex vivo the concentration-ratio delivered by the currently avai...
Pharmacological treatments in asthma-affected horses: A pair-wise and network meta-analysis. Equine asthma is a disease characterised by reversible airflow obstruction, bronchial hyper-responsiveness and airway inflammation following exposure of susceptible horses to specific airborne agents. Although clinical remission can be achieved in a low-airborne dust environment, repeated exacerbations may lead to irreversible airway remodelling. The available data on the pharmacotherapy of equine asthma result from several small studies, and no head-to-head clinical trials have been conducted among the available medications. Objective: To assess the impact of the pharmacological interventions...
Corticosteroids and Immune Suppressive Therapies in Horses. Immune suppressive therapies target exaggerated and deleterious responses of the immune system. Triggered by exogenous or endogenous factors, these improper responses can lead to immune or inflammatory manifestations, such as urticaria, equine asthma, or autoimmune and immune-mediated diseases. Glucocorticoids are the most commonly used immune suppressive drugs and the only ones supported by robust evidence of clinical efficacy in equine medicine. In some conditions, combining glucocorticoids with other pharmacologic and nonpharmacologic treatments, such as azathioprine, antihistamine, broncho...
Inhalation Therapy in Horses. This article discusses the benefits and limitations of inhalation therapy in horses. Inhalation drug therapy delivers the drug directly to the airways, thereby achieving maximal drug concentrations at the target site. Inhalation therapy has the additional advantage of decreasing systemic side effects. Inhalation therapy in horses is delivered by the use of nebulizers or pressured metered dose inhalers. It also requires the use of a muzzle or nasal mask in horses. Drugs most commonly delivered through inhalation drug therapy in horses include bronchodilators, antiinflammatories, and antimicrobi...
Effects of sedation and salbutamol administration on hyperpnoea and tidal breathing spirometry in healthy horses. Sedation is often required to perform pulmonary function testing (PFT) in horses, but drug effects may influence respiratory function. The current study was designed to characterise the effects of sedation and bronchodilator administration on absolute and relative indices of pulmonary function during eupnoeic respiration and carbon dioxide-induced hyperpnoea (rebreathing) in healthy horses using a pneumotachographic spirometry system. Sedation with acetylpromazine (ACP), xylazine, or both drugs in combination was associated with significant reductions in respiratory frequency, minute ventilati...
Bronchopulmonary pharmacokinetics of (R)-salbutamol and (S)-salbutamol enantiomers in pulmonary epithelial lining fluid and lung tissue of horses. Salbutamol is usually administered as a racemic mixture but little is known about the enantioselectivity of salbutamol pharmacokinetics in the lung. This study was designed to investigate enantiomer concentrations in lung tissue after inhaled dosing. Horses (n = 12) received racemic salbutamol 1000 μg via inhalation. Enantioselective ultra performance liquid chromatography-tandem mass spectrometry was used to determine salbutamol concentrations in pulmonary epithelial lining fluid (PELF) sampled 2, 5, 10 and 15 min after administration, in central lung (endoscopic bronchial biopsy) and per...
Detection and pharmacokinetics of salmeterol in thoroughbred horses following inhaled administration. Salmeterol is a man-made beta-2-adrenergic receptor agonist used to relieve bronchospasm associated with inflammatory airway disease in horses. Whilst judicious use is appropriate in horses in training, they cannot race with clinically effective concentrations of medications under the British Horseracing Authority's Rules of Racing. Salmeterol must therefore be withdrawn prior to race day and pharmacokinetic (PK) studies used to establish formal detection time advice. Salmeterol xinafoate (Serevent Evohaler ) was administered (0.1 mg twice daily for 4.5 days) via inhalation to six horses. Ur...
Aerosolized salbutamol (albuterol) improves PaO2 in hypoxaemic anaesthetized horses – a prospective clinical trial in 81 horses. To compare the arterial pH and blood gas values, heart rate and mean arterial blood pressure, in hypoxaemic anaesthetized horses, before and after treatment, with a salbutamol (albuterol) aerosol. Methods: Eighty-one client-owned horses weighing between 114 and 925 kg. Fifty-seven underwent emergency abdominal surgery and 24 were anaesthetized for elective procedures. Methods: Pre-anaesthetic medication included xylazine, detomidine, butorphanol and morphine, alone or in various combinations. Induction of anaesthesia was achieved with guaifenesin and ketamine, diazepam and ketamine, or guaifen...
Control of methylxanthines in the competition horse: pharmacokinetic/pharmacodynamic studies on caffeine, theobromine and theophylline for the assessment of irrelevant concentrations. Methylxanthines positives in competition samples have challenged doping control laboratories and racing jurisdictions since methylxanthines are naturally occurring prohibited substances and often constituents of feed. For theobromine, an international threshold (renamed in International Residue Limit, IRL) of 2 µg/mL in urine has been established. On the basis of the data presented herein, a threshold or rather an IRL for theobromine in plasma of 0.3 µg/mL was proposed and was thereupon approved by the International Federation of Horseracing Authorities (IFHA). Official recommendations f...
Factors affecting the efficiency of aerosolized salbutamol delivery via a metered dose inhaler and equine spacer device. Despite frequent use of metered dose inhalers (MDIs) and spacers in equine practice, limited information exists on the efficiency of aerosol delivery using such devices. We determined the particle size distribution within an MDI-generated salbutamol aerosol delivered via an equine spacer using 'best practice' delivery technique and assessed the effect of variations in MDI use technique (shaking prior to each actuation, rapid repetitive actuations, and MDI angulation) on aerosol delivery efficiency. Under optimal conditions, only 53(±18) μg salbutamol per 100 μg actuation was delivered bey...