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.
Effects of clenbuterol hydrochloride on certain respiratory and cardiovascular parameters in horses performing treadmill exercise. Five standardbred geldings received intravenous clenbuterol hydrochloride and saline in a crossover experiment to evaluate the effects of clenbuterol on certain cardiorespiratory parameters during and after treadmill exercise. The exercise test consisted of four steps. Step 1 at a speed of 76 m per minute, step 2 at 129 m per minute, step 3 at 190 m per minute and step 4 at 236 m per minute. The duration of each step was two minutes, except step 4 which was four minutes. The treadmill was set at a grade of 19 per cent. Before exercise, 30 minutes after clenbuterol or saline administration, art...
Chronic obstructive pulmonary disease in the horse. 2: Therapy. The therapy of equine chronic obstructive pulmonary disease (COPD) essentially entails minimising the horse's exposure to the aetiological antigens which are predominantly thermophilic actinomycetes and moulds occurring in hay and straw. This can be achieved, for example, by keeping affected horses permanently out of doors, or when stabled, using shredded paper, wood shavings or peat moss as bedding and feeding a complete cubed diet. There should be no supplementary hay feeding apart from dust-free vacuum-packed hay. Applying such measures generally allows horses to become asymptomatic in seve...
Chronic obstructive pulmonary disease in the horse. 1: Nature of the disease. The aetiology, pathophysiological changes, pathology and clinical signs of the disease as presently understood are discussed. The condition appears to be a hypersensitivity of the respiratory system in some horses to poor quality hay and straw. Micropolyspora faeni is the chief agent identified in the northern part of the United Kingdom. In other locations, the chief agent is probably different. The principal changes are spasm of the airways and bronchiolitis of the small airways. Onset may be acute or insidious. The chief clinical signs are well known but the disease process is reversible if ...
Equine influenza virus enhances responsiveness of guinea-pig tracheal muscle to isoprenaline. Groups of guinea-pigs were vaccinated with equine influenza A-1 virus and helically-cut tracheal strips were subsequently contracted to carbachol (EC50) and relaxed to isoprenaline at 3, 5 and 10 days post-vaccination. Tracheas from another group were contracted to phenylephrine in the presence of propranolol. Compared to controls, responses to isoprenaline in virus-infected tracheas were significantly potentiated at days 3 and 10. Virus infection significantly inhibited tracheal responsiveness to phenylephrine. It appears that enhancement of isoprenaline may be caused by diminished reactivity...
Chronic respiratory disease in a horse infected with Dictyocaulus arnfieldi. A 6-year-old Thoroughbred gelding was examined because of respiratory disease that developed after it was placed on pasture occupied by a donkey. Clinical signs in the gelding included a harsh, dry paroxysmal cough and increased expiratory effort. Eosinophils were seen in smears of mucus aspirated from the trachea and the bronchi. Immature, 5th-stage Dictyocaulus arnfieldi was identified in the tracheal mucus. The cough and other clinical signs were not diminished by corticosteroid therapy or by the administration of bronchodilators. Treatment with 10-fold therapeutic dosages of thiabendazole ...
Cardiopulmonary effects of clenbuterol in the horse. Clenbuterol, a bronchospasmolytic agent (beta 2 agonist) was studied in terms of its hemodynamic and airflow response in eight, healthy horses. Four animals were instrumented to record intrapleural pressure and air flow, these were used to compute pulmonary resistance, peak flow rates, and tidal volumes. Four animals were instrumented to record pulmonary arterial pressure, carotid arterial pressure, cardiac output, and arterial gas tensions. After control values were recorded, clenbuterol (0.8 microgram/kg) was intravenously administered to each horse in each experiment group. Following clenbu...
Chronic obstructive pulmonary disease (COPD): effects of bronchodilator drugs on normal and affected horses. The effects of the bronchodilator drugs, atropine, isoprenaline and terbutaline, on normal horses and on horses affected with chronic obstructive pulmonary disease (COPD), were assessed by pulmonary function tests and clinical examination. Normal horses were not affected but COPD horses responded by a marked decrease in intrathoracic pressure, a decrease in respiratory rate, an initial decrease followed by an increase in arterial oxygen partial pressure and clinical improvement after treatment with all 3 drugs. These changes were temporary.
Effects of trimetaquinol on equine pulmonary vascular and airway smooth muscle. Trimetaquinol [TMQ: 1-(3’,4‘,5’-trimethoxybenzyl)6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline hydrochloride] a potential p-sympathomimetic bronchodilator (Iwasawa & Kiyomoto 1967), has been shown to be an effective tracheal smooth muscle relaxant in guineapigs (Iwasawa & Kiyomoto 1967; Brittain 1972; Brittain et a1 1970, 1976) and an inhibitor of experimental bronchospasm in guinea-pigs and cats (Brittain et a1 1970; Brittain 1972). In addition, clinical studies with TMQ indicated that the drug was an effective bronchodilator in mild to moderate asthma (Yamamura & Kishimoto 1968). It may...
Pharmacological studies on the pulmonary vein of the horse. I. Effects of selected spasmogens. Horses suffer from a respiratory condition, similar to human allergic asthma, that is characterized by severe dyspnea, wheezing, coughing, and mucus production. Mediator substances released during the allergic reaction may contract airways and pulmonary vasculature. Nothing is known of the effects of autacoids and other vasoactive substances on equine pulmonary vessels. Therefore, spiral strips of equine pulmonary vein were prepared in vitro and the effects of histamine (H), 5-hydroxytryptamine (5HT), bradykinin (BK), carbachol (Carb), and phenylephrine (phen) were studied. The order of contra...
Spasmolytic action of histamine in airway smooth muscle of horse. Histamine, 2-methylhistamine (a specific H1-agonist), 5-HT, PGF2alpha, SRS-A, bradykinin (BK) and carbachol contract bronchial and tracheal smooth muscles of the horse. Isoprenaline, PGE1, E2, dimaprit and 4-methylhistamine (last two = specific H2-agonists) relaxed airways which were partially contracted to carbachol. Mepyramine (a specific H1-antagonist) selectively antagonized contractions to histamine. In the presence of mepyramine, histamine caused relaxation of airways partially contracted to carbachol. Metiamide and burimamide (specific H2-antagonists) specifically antagonized or reverse...
[Veterinary and clinical experience of the use of a beta2-receptor-stimulating sympathicomimetic agent (NAB 365) in horses with respiratory discase (author’s transl)]. The manufacturers state that NAB 365 is a beta2-receptor-stimulating sympathicomimetic agent. According to the medical literature it combines a bronchial antispasmodic effect with certain bronchia secretolytic properties and has few untoward side-effects on, for instance, the heart and intestine. The effectiveness of administration of NAB 365 in horses with chronic or acute respiratory disease was tested in the Department of Veterinary Internal medicine in Utrecht. NAB 365 administered at a dosage of 0.8 gamma/kg, of body weight was found to have a marked bronchodilative effect in horses. Ther...