Topic:Pulmonary Health
Pulmonary health in horses encompasses the study of the respiratory system's function, structure, and disorders within equine species. This area of research addresses various conditions affecting the lungs and airways, such as equine asthma, exercise-induced pulmonary hemorrhage (EIPH), and infectious respiratory diseases. The respiratory system's efficiency is vital for horses, particularly those involved in athletic activities, as it influences performance and overall well-being. Research in pulmonary health investigates diagnostic methods, treatment options, and preventive measures for maintaining respiratory function in horses. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and pathophysiology of the equine respiratory system, as well as the management and therapeutic approaches for respiratory conditions in horses.
Pharmacokinetics of digoxin administered to horses with congestive heart failure. Nine horses with (naturally acquired) congestive heart failure were treated with 2.2 micrograms of digoxin/kg of body weight by the IV route, followed by 11 micrograms/kg administered orally every 12 hours thereafter. Furosemide was administered IV concurrently with IV administered digoxin every 12 hours. Serum concentration of digoxin was measured after the first (IV) and seventh (orally administered) dose. After IV administration, digoxin disposition was described by a 2-compartment model, with a rapid distribution phase (t1/2 alpha = 0.17 hour), followed by a slower elimination phase (beta ...
Evaluation of intradermal mould antigen testing in the diagnosis of equine chronic obstructive pulmonary disease. Intradermal end-point titres for commercial aqueous extracts of Micropolyspora faeni, Thermoactinomyces vulgaris and Aspergillus fumigatus were determined in control and chronic obstructive pulmonary disease (COPD) affected horses. The intradermal end-point titres of control and COPD-affected horses were not significantly different and values for individual horses for M. faeni, A. fumigatus and T. vulgaris were not correlated with the pulmonary dysfunction or with the bronchoalveolar lavage fluid neutrophilia which had been induced by previous inhalation challenges with these antigens and by '...
Furosemide attenuates the exercise-induced increase in pulmonary artery wedge pressure in horses. Right atrial (RA), right ventricular (RV), pulmonary artery (PA), and pulmonary artery wedge (PAW) pressures were examined, using catheter-mounted micromanometers, in 8 healthy horses at rest and during galloping on a treadmill at belt speeds of 8, 10, and 13 m/s. The in vivo signals from the micromanometers were matched with those from conventional fluid-filled catheter transducers leveled at the scapulohumeral joint. Thirty minutes after completing control exercise measurements, furosemide was administered IV at a dosage of 1 mg/kg of body weight, and resting, as well as exercise, measuremen...
Effects of clenbuterol hydrochloride on pulmonary gas exchange and hemodynamics in anesthetized horses. We evaluated the effects of clenbuterol HCl (0.8 micrograms/kg, of body weight, IV), a beta 2 agonist, on ventilation-perfusion matching and hemodynamic variables in anesthetized (by IV route), laterally recumbent horses. The multiple inert gas elimination technique was used to assess pulmonary gas exchange. Clenbuterol HCl induced a decrease in arterial oxygen tension (from 57.0 +/- 1.8 to 49.3 +/- 1.2 mm of Hg; mean +/- SEM) as a result of increased shunt fraction (from 6.6 +/- 2.1 to 14.4 +/- 3.1%) and ventilation to regions with high ventilation-perfusion ratios. In contrast, no changes in...
In vitro effects of alpha 2-adrenergic receptor stimulation on cholinergic contractions of equine distal airways. In horses with noninduced, reversible airway obstruction (heaves), pulmonary function is improved after sedation with the alpha 2-adrenergic agonist xylazine. The mechanism of this effect is undetermined. Because the predominant excitatory innervation of equine airways is cholinergic, the influence of alpha 2-adrenergic receptor stimulation on the response of isolated distal airways to cholinergic stimulation was determined. Distal bronchial segments from 22 healthy horses were suspended in isolated organ baths where their mechanical responses to various stimuli could be studied. Each tissue w...
Effect of stabling on bronchoalveolar cells obtained from normal and COPD horses. Bronchoalveolar lavages (BAL) were performed before and after 3 weeks of housing in 5 horses suffering from COPD and 5 normal horses. In the two groups, the total number of cells recovered remained unchanged after stabling. The most common cell populations in BAL fluid of control animals were alveolar macrophages (46.4%) and lymphocytes (44.9%). The percentage of neutrophils increased after stabling from 8.7% to 27.6%. In COPD horses, lymphocytes predominated (40.7%) in animals at pasture with neutrophils increasing from 29.4% to 71.6% after stabling. After fractionation by Percoll density gra...
Successful resection of a recurrent leiomyosarcoma of the pulmonary trunk. We successfully performed a total resection of the pulmonary artery trunk and replaced it with an equine pericardial xenograft roll in a patient with a recurrent leiomyosarcoma. We believe, based on anatomic and embryologic principles, total rather than partial resection of the pulmonary artery trunk should be the treatment of choice for primary leiomyosarcomas of the pulmonary artery.
Pulmonary edema associated with transient airway obstruction in three horses. Pulmonary edema associated with transient airway obstruction was detected in 3 horses. The cause of obstruction was different in each horse, but after relief of the obstruction, clinical signs and radiographic abnormalities were indicative of pulmonary edema. In 2 of the 3 horses, pink frothy fluid was evident in the airways. The horses were treated with furosemide, nasal insufflation of O2, anti-inflammatory agents, and anti-biotics. Of the 3 horses examined, 1 horse died acutely, 1 horse recovered fully, and 1 developed pleuritis and was subsequently euthanatized.
Phenotypic analysis of peripheral blood and bronchoalveolar lavage fluid lymphocytes in control and chronic obstructive pulmonary disease affected horses, before and after ‘natural (hay and straw) challenges’. Phenotypic analysis of lymphocytes in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) of control and chronic obstructive pulmonary disease (COPD) affected horses, both before and after 'natural (hay and straw) challenge', were performed using immunofluorescent labelling with monoclonal antibodies and flow cytometry. BALF lymphocytes were shown to be predominantly EqCD5+ cells, approximately half of which were also EqCD8+, with a smaller proportion of B cells. In comparison with PB, BALF contained higher proportions of EqCD5+ cells and EqCD8+ cells and a lower proportion of B cell...
Quantification of histamine in plasma and pulmonary fluids from horses with chronic obstructive pulmonary disease, before and after ‘natural (hay and straw) challenges’. A commercial radioimmunoassay kit was used to quantify histamine concentrations of plasma, bronchoalveolar lavage fluid (BALF) and pulmonary epithelial lining fluid (PELF) of normal horses and horses with chronic obstructive pulmonary disease (COPD), before and after 'natural (hay and straw) challenge' (NC). There were no significant changes in the concentrations of histamine in plasma or BALF at 0.5 or 5 h after NC, but the PELF histamine concentration of COPD affected horses was significantly increased at 5 h, but not at 0.5 h, following NC. As the histamine concentrations of whole BALF lysa...
Distribution of dopamine beta-hydroxylase and neuropeptide Y-immunoreactive nerves in healthy equine lungs. Immunohistochemical methods were used to determine the distribution of pulmonary nerves containing either an enzymatic marker of adrenergic nerves, dopamine beta hydroxylase, or the putative neurotransmitter neuropeptide Y in 7 equids with healthy lungs. Nerves immunoreactive for these substances were found on airway smooth muscle in nearly all the samples of healthy equine lung examined. These nerves were generally more numerous in the larger airways but could be detected even in noncartilaginous bronchioles. Pulmonary and bronchial vessels also contained numerous immunoreactive nerves. On th...
Breathing periodicity in intact and carotid body-denervated ponies during normoxia and chronic hypoxia. Periodic oscillations in pulmonary ventilation (VI), tidal volume (VT), and inspiratory and expiratory times (TI and TE) were studied during normoxia (arterial PO2 = 95 Torr) and 48 h of hypoxia (arterial PO2 = 40-50 Torr) in awake intact (n = 8) and carotid body-denervated (CBD; n = 8) ponies. Periodic oscillations were identified by fast-Fourier transformation of breath-by-breath data and quantitated by determining the power ratio of significant periodic oscillations to total power of data sequence. Periodic oscillations of 0.063-0.500 cycles/breath were observed in all parameters during bot...
Temporary bilateral laryngeal paralysis in a horse associated with general anaesthesia and post anaesthetic myositis. An eight-year-old Highland pony which had previously shown normal laryngeal function, underwent general anaesthesia for surgical treatment of a mandibular sinus. During its recovery from the anaesthesia, the pony suffered great respiratory distress and stridor, due to total bilateral laryngeal paralysis and pulmonary oedema. The animal was immediately given a temporary tracheostomy. Some hours later, postoperative myositis developed; it resolved within two days and the pony's laryngeal function returned to normal during the following year.
Cardiac output but not high pulmonary artery pressure varies with FIO2 in exercising horses. Horses have high mean pulmonary artery pressure (Ppa) both at rest and during exercise (approximately 30 and > or = 80 mmHg, respectively). The mechanisms are unknown. To see if hypoxic pulmonary vasoconstriction (HPV) plays a role, we compared pulmonary artery pressure-flow (Ppa-Q) curves when inspired O2 fraction (FIO2) was 0.16, 0.21, and 0.30, in 5 normal Thoroughbred horses standing quietly and while galloping at 10 and 14 m/sec on a level treadmill. We calculated O2 consumption (VO2) from measurements of respired gas composition and flow, and calculated Q from VO2 and measurements of ...
Pulmonary artery wedge pressure increases with high-intensity exercise in horses. Using catheter mounted microtip manometers, right atrial, pulmonary artery, and pulmonary artery wedge pressures were studied in 8 horses while they were standing quietly (rest), and during galloping at treadmill speeds of 8, 10, and 13 m/s. At rest, mean (+/- SEM) heart rate, mean right atrial pressure, mean pulmonary artery pressure, and mean pulmonary artery wedge pressure were 37 (+/- 2) beats/min, 8 (+/- 2) mm of Hg, 31 (+/- 2) mm of Hg, and 18 (+/- 2) mm of Hg, respectively. Exercise at treadmill belt speed of 8 m/s resulted in significant (P < 0.05) increments in heart rate, right at...
Hypertrophic osteopathy in three horses and a pony. Hypertrophic osteopathy was diagnosed in 3 horses and in a pony, ranging in age from 8 to 21 years. There were 2 females, 1 sexually intact male, and 1 gelding. In 3 animals, hypertrophic osteopathy was associated with pulmonary abscesses, bronchogenic squamous cell carcinoma, and ovarian granulosa-cell tumor, respectively, and resulted in death or euthanasia. Duration of the condition ranged from 1 to 4 months. In 1 horse, hypertrophic osteopathy was believed to be secondary to pregnancy, and resolved following uncomplicated delivery of a live foal.
Presence of pulmonary intravascular macrophages in the equine lung: some structuro-functional properties. The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monast...
Temporal effects of inhaled histamine and methacholine aerosols on the pulmonary mechanics of thoroughbred horses. This paper presents a method for on-line determination of pulmonary mechanics in standing, non-sedated horses during and following inhalation of aerosolized drug solutions. This method was used to evaluate the temporal effects of inhaled histamine and methacholine aerosols on pulmonary mechanics in 18 Thoroughbred horses. The following were concluded from this study. The extremely large between-breath variation, for all variables used to evaluate pulmonary mechanics in the horse, limits the usefulness of these variables for modeling the non-specific pulmonary responses to inhaled stimulants on...
Arterial-venous difference in atrial natriuretic peptide concentration during exercise in horses. Six nontrained mares were subjected to steady-state, submaximal treadmill exercise to examine the effect of exercise on the plasma concentration of atrial natriuretic peptide (ANP) in arterial, compared with mixed venous, blood. Horses ran on a treadmill up a 6 degree grade for 20 minutes at a speed calculated to require a power equivalent to 80% of maximal oxygen uptake (VO2MAX). Arterial and mixed venous blood samples were collected simultaneously from the carotid and pulmonary arteries of horses at rest and at 10 and 20 minutes of exercise. Plasma was stored at -80 C and was later thawed; A...
Effects of xylazine on airway function in ponies with recurrent airway obstruction. The effect of IV administration of the alpha 2-adrenoceptor agonist xylazine hydrochloride (0.5 mg/kg of body weight) was examined in ponies with recurrent obstructive pulmonary disease, commonly called heaves. Six ponies with the disease (principals) were studied during clinical remission and during an acute attack of airway obstruction precipitated by stabling and feeding of dusty hay. Six control ponies were also studied. In principal ponies with airway obstruction, xylazine administration significantly (P < 0.05) decreased pulmonary resistance and increased dynamic compliance, but did n...
Evaluation of clinical signs of disease, bronchoalveolar and tracheal wash analysis, and arterial blood gas tensions in 13 horses with chronic obstructive pulmonary disease treated with prednisone, methyl sulfonmethane, and clenbuterol hydrochloride. We evaluated the efficacy of 3 treatments for chronic obstructive pulmonary disease in horses: prednisone (400 mg/horse, PO, daily; n = 7), methyl sulfonmethane (10 g/horse, PO, q 12 h; n = 6), and clenbuterol hydrochloride (0.4 mg/horse, PO, q 12 h; n = 7). A fourth group acted as controls (n = 6) and was not treated. The treatment period lasted 10 days. Each horse was a member of 2 different groups for 10 days, separated by an 18-day interval of no treatment. All horses were housed together in an outdoor pen without bedding. Horses were fed alfalfa/grass hay mix ad libitum from a large feede...
Respiratory mucociliary clearance in the horse in health and disease, and its pharmaceutical modification. The structure and possible functions of respiratory secretions are reviewed. In the equine, goblet (mucus producing) cells are the main source but little information is available on the volume or composition of equine respiratory secretions. Airway mucus has complex and incompletely understood physical characteristics which can be partially assessed by a wide range of in vitro and biological techniques. The complex relationship between mucus structure and its propulsion by the airway cilia are discussed, both in health and with pulmonary disease. Mucokinesis in the horse has been assessed visu...
Effect of head and neck position on respiratory mechanics in horses sedated with xylazine. We studied the temporal changes in respiratory mechanics associated with xylazine administration (1.1 mg/kg of body weight, IV) in standing horses (experiment 1), and determined the effects of head and neck position (experiment 2) and atropine administration (experiment 3) on the observed changes. Thoroughbred geldings, 3 to 5 years old (5 in experiment 1, 4 in experiments 2 and 3) were used. Flow rates were obtained from a pneumotachograph and a differential transducer attached to a tight-fitting mask. Electronic integration of the flow signal gave tidal volume. Total pulmonary pressure (PL) ...
Influence of cyclooxygenase inhibitors on furosemide-induced hemodynamic effects during exercise in horses. Furosemide, which commonly is used as a prophylactic treatment for exercise-induced pulmonary hemorrhage in horses, may mediate hemodynamic changes during exercise by altering prostaglandin metabolism. To determine if furosemide's hemodynamic effects during exercise in horses could be reversed, cyclooxygenase inhibitors were administered with furosemide. Four treatments were administered 4 hours prior to treadmill exercise at 9 and 13 m/s. They included a control treatment (10 ml of 0.9% NaCl solution, IV), furosemide (1 mg/kg of body weight, IV) administered alone, and furosemide in combinati...
Respiratory mechanics of horses during stepwise treadmill exercise tests, and the effect of clenbuterol pretreatment on them. Normal Standardbred horses were given an incremental exercise test on a horizontal treadmill to evaluate the influence of exercise on gas exchange, resistance, dynamic compliance and inertance of the respiratory system. The exercise test consisted of 2 min exercise steps at each of the following speeds: 2.4 m/sec (walk), 4.5 m/sec (slow trot), 7.0 m/sec (fast trot) and 10 m/sec (gallop). At rest and after 1 min of exercise at each step, airflow, tidal volume, respiratory frequency, pharyngeal, mid-oesophageal and transdiaphragmatic pressures and arterial blood gas tensions were measured. The s...
Preliminary observations on inhalation and intradermal challenges of horses with oil seed rape. Horses with asymptomatic or symptomatic chronic obstructive pulmonary disease (COPD) and control horses were challenged with oil seed rape either by exposure to a field of flowering Brassica campestris for six days, or by an inhalation challenge with freshly collected pollen from Brassica napus, or by inhalation challenge with a commercial extract of B napus pollen. Clinical and bronchoscopic examinations showed that the challenges did not induce detectable pulmonary disease in the control or asymptomatic COPD affected horses and did not significantly affect their pulmonary mechanics, arterial...
Effects of transport on constituents of bronchoalveolar lavage fluid from horses. To determine whether road transport affected pulmonary phagocyte activity, 7 healthy Thoroughbred horses were shipped 1,160 kilometers over 36 hours. Fluid collected by bronchoalveolar lavage (BAL) 12 hours, and 7 and 14 days after transport was analyzed. Results were compared to those from the same horses pre-transport, and 7 non-transported control horses that had BAL performed at the same times as the transported horses. Of cells recovered with BAL the percentage of viable pulmonary alveolar macrophages (PAMs) declined from 90.0 +/- 0.9% pre-transport to 80.0 +/- 3.7% by 2 weeks post transp...