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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.
Equine pulmonary disease: a case control study of 300 referred cases. Part 3: Ancillary diagnostic findings. The majority of 270 adult horses with chronic pulmonary diseases had excessive volumes of respiratory secretions (RS) present in their trachea, elevated tracheal RS neutrophil ratios and lowered arterial oxygen partial pressures. Some control horses, had inexplicably elevated trachael RS neutrophil ratios. Only the chronic obstructive pulmonary disease (COPD) affected group had significantly elevated bronchoalveolar lavage fluid (BALF) neutrophil ratios. Maximal intrapleural pressure changes (max dPpl) were raised in 48% of COPD cases and rarely with other pulmonary disorders. Arterial pH or c...
An immunohistochemical study of three equine pulmonary granular cell tumors. Granular cell tumor (GCT) is a morphologic designation for tumors of varied histogenesis. Most GCTs in human beings are derived from Schwann cells, and rat meningeal GCTs are believed to originate in the neural crest. Three equine pulmonary GCTs from aged horses were studied immunohistochemically with primary antibodies directed against vimentin, cytokeratins (AE1/AE3), S-100, Leu 7, desmin, and neuron-specific enolase (NSE) using a steptavidin-biotin procedure. All three tumors stained similarly with strong and diffuse staining of neoplastic cells for vimentin and S-100 and negative staining ...
Equine pulmonary disease: a case control study of 300 referred cases. Part 4: Treatments and re-examination findings. One-hundred and forty-seven of 270 (54.4%) horses suffering from pulmonary disorders were given at least one re-examination including, clinical, bronchoscopic, pulmonary function and cytological examinations after treatment and a further 83 of these horses (30.7%) had their clinical progress assessed by verbal or written reports. These examinations and progress reports showed high levels of partial or total recovery for most pulmonary disease categories, including chronic obstructive pulmonary disease, infectious, S. zooepidemicus and undifferentiated pulmonary disease and lungworm infection g...
Equine pulmonary disease: a case control study of 300 referred cases. Part 1: Examination techniques, diagnostic criteria and diagnoses. Three-hundred adult horses, referred from 1990 to 1993 inclusively, for pulmonary examination were assessed using standardised history taking and clinical, intrapleural pressure, arterial blood gases and pH, bronchoscopic and tracheal and broncho-alveolar lavage fluid (BALF) cytological examinations. Two-hundred and thirty-five cases were referred with overt signs of pulmonary disease and the remaining 65 cases were referred for pulmonary examination because of reduced exercise (usually racing) performance or prolonged dyspnoea after racing. No pulmonary disease was detected in 30 cases. The 2...
Pulsed wave Doppler echocardiography in normal horses. Reference values were established for selected Doppler derived variables from a group of 40 normal Thoroughbred and Thoroughbred cross horses. Standard two-dimensional (2-D) images used for guiding the Doppler sampling site allowed accurate alignment with flow. Tricuspid inflow velocities during rapid filling (E) and atrial contraction (A) were significantly higher when recorded from a right parasternal angled view than from a right parasternal long-axis view. In 8 horses the tricuspid inflow peak A velocity was higher than the peak E velocity. The peak acceleration of blood flow was higher (P...
Pharmacologic interaction of furosemide and phenylbutazone in horses. The effect of premedication with phenylbutazone on systemic hemodynamic and diuretic effects of furosemide was examined in 6 healthy, conscious, mares. Mares were instrumented for measurement of systemic hemodynamics, including cardiac output and pulmonary arterial, systemic arterial, and intracardiac pressures, and urine flow. Each of 3 treatments was administered in a randomized, blinded study; furosemide (1 mg/kg of body weight, IV) only, phenylbutazone (8.8 mg/kg, PO, at 24 hours and 4.4 mg/kg, IV, 30 minutes before furosemide) and furosemide, or 0.9% NaCl. Phenylbutazone administration si...
Cytokine modulation alters pulmonary clearance of Rhodococcus equi and development of granulomatous pneumonia. Rhodococcus equi, a facultative intracellular bacterium, causes chronic, often fatal granulomatous pneumonia in young horses and in humans with AIDS. The inability of host alveolar macrophages to kill intracellular R. equi results in the development of granulomas and progressive loss of pulmonary parenchyma. Clearance of the organism from the lung requires functional CD4+ T cells. The purpose of this study was to identify the cytokine effector mechanisms that mediate clearance of R. equi from the lung. Mice were treated with monoclonal antibodies (MAbs) to either gamma interferon (IFN-gamma) o...
Partitioning of total pulmonary resistance in horses. The partitioning of total pulmonary resistance (RL) into upper airway resistance and lower airway resistance (RI) was studied in 8 Thoroughbred geldings. In addition, the phase shift and amplitude distortion of 3 catheters used for pressure measurements in this study were evaluated under static and dynamic conditions. Flow rate was obtained from a heated pneumotachograph attached to a tight-fitting mask placed over the nose. Electronic integration of the flow signal gave tidal volume. Transpulmonary pressure (PL) was obtained from calculation of the difference between the esophageal balloon ca...
Effects of glyceryl trinitrate (nitroglycerin) on pulmonary vascular pressures in standing thoroughbred horses. Strenuously exercising Thoroughbreds exhibit a dramatic increase in pulmonary capillary blood pressure, which contributes to stress failure of pulmonary capillaries resulting in exercise induced pulmonary haemorrhage (EIPH). One strategy to prevent EIPH is, therefore, to lower the pulmonary capillary blood pressure of exercising horses. Recent work in several species suggests that nitric oxide plays a significant role in maintaining low vascular resistance in the pulmonary circulation; however, the effects of nitrovasodilators (which work via the same mechanism as nitric oxide) on equine pulmo...
Cardiopulmonary effects of hypercapnia during controlled intermittent positive pressure ventilation in the horse. The cardiopulmonary effects of eucapnia (arterial CO2 tension [PaCO2] 40.4 +/- 2.9 mm Hg, mean +/- SD), mild hypercapnia (PaCO2, 59.1 +/- 3.5 mm Hg), moderate hypercapnia (PaCO2, 82.6 +/- 4.9 mm Hg), and severe hypercapnia (PaCO2, 110.3 +/- 12.2 mm Hg) were studied in 8 horses during isoflurane anesthesia with volume controlled intermittent positive pressure ventilation (IPPV) and neuromuscular blockade. The sequence of changes in PaCO2 was randomized. Mild hypercapnia produced bradycardia resulting in a significant (P < 0.05) decrease in cardiac index (CI) and oxygen delivery (DO2), while ...
Equine herpesvirus 2 in pulmonary macrophages of horses. In a search of viral agents in pulmonary macrophages of horses with chronic pulmonary disease, equine herpesvirus 2 was found to be unique. In 8 of 9 horses with chronic pulmonary disease, antigens of equine herpesvirus 2 were detected by indirect immunofluorescence staining of scattered foamy macrophages immediately after harvesting by bronchoalveolar lavage and fractionation on metrizamide gradients. In a healthy horse, antigens were not found. After 1 week of cultivation of bronchoalveolar lavage cells from a second group of 9 horses with chronic pulmonary disease, viral antigens were detec...
Hypoxic helium breathing does not reduce alveolar-arterial PO2 difference in the horse. In a previous study we evaluated the mechanism of alveolar-arterial PO2 (AaPO2) reduction when nitrogen is replaced with helium in normoxia (FIO2 = 0.21). The reduction in AaPO2 was not due to changes in VA/Q inequality, pulmonary O2 diffusing capacity, or cardiac output, but to more complete diffusion equilibration as a consequence of the higher ventilation and thus PAO2 (which reduced the average slope of the hemoglobin O2 dissociation curve (ODC), and thus enhanced diffusive equilibration). We hypothesized that hypoxic He/O2 breathing in contrast would not reduce the AaPO2 because PAO2 and ...
Haemodynamic effects of hyoscine-N-butylbromide in ponies. The haemodynamic effects of hyoscine-N-butylbromide (0.30 mg/kg, intravenously) were studied in eight adult ponies in a blinded two-period crossover experiment with repeated measures. Values for heart rate were 63%, 48% and 13% greater than control values at 1, 16 and 46 min, respectively, after administration of hyoscine-N-butylbromide. Cardiac output increased by 16% at 16 min after drug injection. Mean right atrial pressure was decreased by 79%, 63%, 45% and 52% at 1, 16, 46 and 61 min, respectively, after drug administration. Stroke volume was decreased by 32% at 1 min and pulmonary arteri...
A pulmonary granular cell tumour with associated hypertrophic osteopathy in a horse. Abstract Extract A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.
The effects of three models of airway disease on tidal breathing flow-volume loops of thoroughbred horses. The effects of histamine and methacholine aerosols and of a fixed inspiratory resistance on tidal breathing flow-volume loops (TBFVL) were investigated using 18 unsedated, standing, healthy thoroughbred horses. The data were first analysed using traditional flow-volume loop indices and then reduced using standardized factor scoring coefficients obtained in a previous study in this laboratory using similar experimental techniques. On the basis of resting TBFVL analysis, the degree of pulmonary dysfunction caused by inhalation of histamine and methacholine aerosols with concentrations of 10 and ...
Characterization of normal tidal breathing flow-volume loops for thoroughbred horses. The purpose of this study was to characterize the normal equine tidal breathing flow-volume loop (TBFVL). The study was performed using 18 healthy Thoroughbred horses. TBFVLs constructed from data collected from resting horses had a typical biphasic inspiratory and expiratory phase. The interindividual variability of the indices used to describe TBFVLs was in the range 16-32%, which is comparable to the variability of other measures of equine pulmonary mechanics. The large variability of these data probably limits the value of resting TBFVL indices for detecting subclinical respiratory conditi...
Stress failure of pulmonary capillaries as a limiting factor for maximal exercise. The pulmonary blood-gas barrier has a basic physiological dilemma. On the one hand it needs to be extremely thin for efficient gas exchange. On the other hand it also needs to be immensely strong because the stresses on the pulmonary capillary wall become extremely high when the capillary pressure rises on exercise. Maximal hydrostatic pressures in human pulmonary capillaries during exercise are not accurately known but must exceed 30 mmHg. In some animals, for example thoroughbred horses, the capillary pressure rises to about 100 mmHg. These pressures cause stresses in the capillary wall of 5...
Effect of prior lavage on bronchoalveolar lavage fluid cell population of lavaged and unlavaged lung segments in horses. Bronchoalveolar lavage (BAL) was performed on 16 horses to determine whether it caused local or diffuse inflammation in the lungs. In 7 horses, BAL was performed in both lungs twice, 48 hours apart. Although total cell counts of the BAL samples did not change significantly, there were increased numbers and percentage of neutrophils in the second lavage fluid samples. In 5 horses, BAL was performed in 1 lung and repeated 48 hours later in the same lung and in the corresponding airway in the contralateral lung. The absolute cell count and percentage of neutrophils were significantly (P = < 0....
Stress failure of pulmonary capillaries as a mechanism for exercise induced pulmonary haemorrhage in the horse. Exercise induced pulmonary haemorrhage (EIPH) is a serious problem in the Thoroughbred industry. The condition apparently occurs essentially in all Thoroughbreds in training but the mechanism has proved elusive. There is now strong evidence that the condition is caused by mechanical failure of the walls of the pulmonary capillaries when the pressure inside them rises to very high levels. It is well known that pulmonary capillaries have extremely thin walls to allow rapid exchange of respiratory gases across them. Recently we have shown that the wall stresses are very large when the capillary t...
Distribution of SP- and CGRP-like immunoreactive nerve fibers in the lower respiratory tract of neonatal foals: evidence for loss during development. The lungs of neonatal foals contain many nerves immunoreactive for substance P and calcitonin gene-related peptide. These nerves are closely associated with the epithelium, bronchial and pulmonary vessels and the airway smooth muscle of all intrathoracic airways, including non-cartilaginous bronchioles. Activation of sensory nerves in the respiratory epithelium could thus potentially affect, via local axon reflexes, vascular and respiratory smooth muscle in neonatal equine airways. Nerves immunoreactive for these peptides are much more widely distributed within the lung than in adult horses; t...
Pulmonary vascular pressures of thoroughbreds increase rapidly and to a higher level with rapid onset of high-intensity exercise than slow onset. Previous studies of pulmonary vascular pressures have utilised gradual incremental step exercise protocols, but in competitive racing at the track, horses perform rapid acceleration high-intensity exercise. The rate of rise in pulmonary vascular pressures under conditions of quick onset high-intensity exercise is unknown. Catheter mounted manometers, whose in vivo signals were matched with pressure signals obtained via transducers connected to fluid-filled lumens from same cardiovascular sites, were used to compare right heart and pulmonary vascular pressures in 8 healthy Thoroughbreds perform...
A survey of exercise-induced pulmonary haemorrhage in Quebec standardbred racehorses. Sixty Standardbred horses, aged 3 to 10 years, were examined endoscopically for exercise-induced pulmonary haemorrhage (EIPH) 1 h after racing, on at least 3 occasions. Racing time, finishing position and post exercise venous lactate concentrations were also recorded. Horses positive for tracheal blood on endoscopy were classified as having either grade 1 EIPH (one or a few spots of blood in the trachea), or grade 2 (stream of blood). Air temperature, relative humidity and air pollutant levels were recorded on each examination day. Of the 60 horses, 52 (87%) were EIPH-positive on at least one ...
Endocarditis and pulmonary aspergillosis in a horse. No abstract available
Quantitation of alpha-1 proteinase inhibitor in the pulmonary epithelial lining fluid of horses with chronic obstructive pulmonary disease. The concentration of alpha-1 proteinase inhibitor (API) was measured in the pulmonary epithelial lining fluid (PELF) of horses with chronic obstructive pulmonary disease (COPD) while they had clinical signs and while they had none. The concentrations of total protein, albumin and API were significantly higher in the PELF of animals with clinical signs of COPD. The correlation between albumin and API in the PELF suggested that most of the API was derived from the serum.
Phagocytic activity of polymorphonuclear leukocytes lavaged from the lungs of horses with clinically diagnosed chronic pulmonary disease. The aim of this study was to compare phagocytic activity of polymorphonuclear cells (PMNs) from the bronchoalveolar lavage of clinically healthy horses and those with severe chronic bronchiolitis. Research was carried out on 28 horses. Chronic inflammation of the lower airways was diagnosed in nine horses. Cells from the respiratory tract were lavaged according to accepted methods. For comparison, PMNs were isolated from peripheral blood of all investigated horses. The phagocytic activity of PMNs was determined in relation to two standard strains of Staphylococcus aureus, Staph, aureus Smith w...
Pulmonary vascular pressures of strenuously exercising thoroughbreds after administration of flunixin meglumine and furosemide. High-intensity exercise results in a dramatic increase in mean pulmonary capillary blood pressure of horses, and administration of furosemide 4 hours before exertion significantly attenuates this exercise-induced increment. To test whether this effect of furosemide is mediated via release of prostaglandins, right atrial and pulmonary vascular pressures were measured in 8 healthy, sound, exercise-trained Thoroughbreds at rest and during incremental-step exercise on a treadmill. Horses were studied on 3 separate occasions: after i.v. administration of saline (0.9% NaCl) solution, after administr...
Substance P and calcitonin gene-related peptide-like immunoreactive nerve fibers in lungs from adult equids. Distribution of pulmonary nerves immunoreactive for either substance P or calcitonin gene-related peptide was determined, using immunohistochemical methods on healthy lungs from adult equids. The overall patterns of distribution of substance P and calcitonin gene-related peptide-like immunoreactivity were similar. Distribution of immunoreactive nerves was not uniform throughout the lungs; nerve fibers immunoreactive for these peptides were more frequently observed near the hilus of the lung than in the caudal lobes or in the periphery of the lung. Nerve fibers immunoreactive for substance P or...
