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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.
Gammaherpesviruses and pulmonary fibrosis: evidence from humans, horses, and rodents. Progressive lung fibrosis in humans, typified by idiopathic pulmonary fibrosis (IPF), is a serious cause of morbidity and mortality in people. Similar diseases have been described in dogs, cats, and horses. The cause and pathogenesis of such diseases in all species is poorly understood. There is growing evidence in human medicine that IPF is a manifestation of abnormal wound repair in response to epithelial injury. Because viruses can contribute to epithelial injury, there is increasing interest in a possible role of viruses, particularly gammaherpesviruses, in the pathogenesis of pulmonary fi...
Arterial oxygen tension and pulmonary ventilation in horses placed in the Anderson Sling suspension system after a period of lateral recumbency and anaesthetised with constant rate infusions of romifidine and ketamine. Some controversy exists over whether or not horses' recovery and cardiopulmonary function are affected by suspension in slings. Objective: To measure arterial oxygen tension and pulmonary ventilation in anaesthetised horses placed in a standing position in an Anderson Sling (AS) after a period of right lateral recumbency (RLR). Methods: Randomised crossover experimental study. Methods: Six Standardbred horses were anaesthetised twice. Catheters were inserted into the right jugular vein and the left carotid artery. After premedication with romifidine, anaesthesia was induced with diazepam and k...
Interstitial lung disease associated with Equine Infectious Anemia Virus infection in horses. EIA (Equine Infectious Anemia) is a blood-borne disease primarily transmitted by haematophagous insects or needle punctures. Other routes of transmission have been poorly explored. We evaluated the potential of EIAV (Equine Infectious Anemia Virus) to induce pulmonary lesions in naturally infected equids. Lungs from 77 EIAV seropositive horses have been collected in Romania and France. Three types of lesions have been scored on paraffin-embedded lungs: lymphocyte infiltration, bronchiolar inflammation, and thickness of the alveolar septa. Expression of the p26 EIAV capsid (CA) protein has been...
Study of lysozyme resistance in Rhodococcus equi. Lysozyme is an important and widespread component of the innate immune response that constitutes the first line of defense against bacterial pathogens. The bactericidal effect of this enzyme relies on its capacity to hydrolyze the bacterial cell wall and also on a nonenzymatic mechanism involving its cationic antimicrobial peptide (CAMP) properties, which leads to membrane permeabilization. In this paper, we report our findings on the lysozyme resistance ability of Rhodococcus equi, a pulmonary pathogen of young foals and, more recently, of immunocompromised patients, whose pathogenic capacity...
Experimental induction of pulmonary fibrosis in horses with the gammaherpesvirus equine herpesvirus 5. Gammaherpesviruses (γHV) are implicated in the pathogenesis of pulmonary fibrosis in humans and murine models of lung fibrosis, however there is little direct experimental evidence that such viruses induce lung fibrosis in the natural host. The equine γHV EHV 5 is associated with equine multinodular pulmonary fibrosis (EMPF), a progressive fibrosing lung disease in its natural host, the horse. Experimental reproduction of EMPF has not been attempted to date. We hypothesized that inoculation of EHV 5 isolated from cases of EMPF into the lungs of clinically normal horses would induce lung fibr...
Comparison of tulathromycin, azithromycin and azithromycin-rifampin for the treatment of mild pneumonia associated with Rhodococcus equi. The objectives of the present study were to determine the relative efficacy of tulathromycin, azithromycin, or azithromycin with rifampin for the treatment of pulmonary abscesses on a farm with endemic infections caused by Rhodococcus equi. Foals with ultrasonographic evidence of pulmonary abscesses (abscess score 8.0-15 cm; n=120) were randomly allocated in four equal treatment groups: (1) tulathromycin intramuscularly; (2) azithromycin monotherapy, orally; (3) azithromycin with rifampin, orally; (4) saline intramuscularly as a placebo. Physical examination and thoracic ultrasonography were p...
Plasma and pulmonary pharmacokinetics of desfuroylceftiofur acetamide after weekly administration of ceftiofur crystalline free acid to adult horses. Current labelling for the use of ceftiofur crystalline free acid (CCFA) in horses states that 2 i.m. doses must be administered 4 days apart to provide 10 days of therapeutic coverage. A 10 day treatment regimen is not sufficient for the long-term treatment of horses with severe lung consolidation or pleuropneumonia. There are currently no data to guide an appropriate dosing interval when a longer treatment regimen is warranted. Objective: To determine steady-state plasma and pulmonary epithelial lining fluid (PELF) concentrations of desfuroylceftiofur acetamide (DCA) after weekly i.m. adminis...
Qualitative and quantitative interpretation of computed tomography of the lungs in healthy neonatal foals. To qualitatively describe lung CT images obtained from sedated healthy equine neonates (≤ 14 days of age), use quantitative analysis of CT images to characterize attenuation and distribution of gas and tissue volumes within the lungs, and identify differences between lung characteristics of foals ≤ 7 days of age and foals > 7 days of age. Methods: 10 Standardbred foals between 2.5 and 13 days of age. Methods: Foals were sedated with butorphanol, midazolam, and propofol and positioned in sternal recumbency for thoracic CT. Image analysis software was used to exclude lung from nonlung str...
Effects of exercise on markers of venous remodeling in lungs of horses. To determine the effects of 2 weeks of intense exercise on expression of markers of pulmonary venous remodeling in the caudodorsal and cranioventral regions of the lungs of horses. Methods: 6 horses. Methods: Tissue samples of the caudodorsal and cranioventral regions of lungs were obtained before and after conditioning and 2 weeks of intense exercise. Pulmonary veins were isolated, and a quantitative real-time PCR assay was used to determine mRNA expression of matrix metalloproteinase-2 and -9, tissue inhibitor of metalloproteinase-1 and -2, collagen type I, tenascin-C, endothelin-1, platelet...
Breathing pattern and thoracoabdominal asynchrony in horses with chronic obstructive and inflammatory lung disease. The aim of the study was to show that changes in thoracoabdominal asynchrony (TAA) between quiet breathing and CO2-induced hyperpnoea can be used to differentiate between horses with healthy airways and those suffering from inflammatory airway disease (IAD) or recurrent airway obstruction (RAO). The level of TAA was displayed by the Pearson's correlation coefficient (PCC) of thoracic and abdominal signals, generated by respiratory ultrasonic plethysmography (RUP) during quiet breathing and hyperpnoea. Changes in TAA were expressed as the quotient of the PCCs (PCCQ) during normal breathing and ...
Experimental model of equine alveolar macrophage stimulation with TLR ligands. Pulmonary diseases are common in horses and have a major economic impact on the equine industry. Some of them could be associated with an inadequate immune response in the lung, but methods to evaluate this response in horses are lacking. The aim of this study was to develop and validate an experimental model that could be applied in several physiological and pathological conditions to assess the innate immune response of equine pulmonary cells. Equine alveolar macrophages (AMs) obtained from bronchoalveolar lavages were isolated from other cells by adhesion. TLR2, 3, and 4 expression in AMs w...
Telemetric analysis of breathing pattern variability in recurrent airway obstruction (heaves)-affected horses. To use noninvasive respiratory inductance plethysmography (RIP) to investigate differences in breathing patterns between horses with and without recurrent airway obstruction (RAO) during the onset of airway obstruction induced through confinement to stables. Methods: 12 horses with no history or clinical signs of respiratory disease (control horses) and 7 RAO-affected horses. Methods: The study involved 2 phases. In phase 1, the optimal position of RIP bands for recording pulmonary function was investigated in 12 control horses. In phase 2, 7 RAO-affected and 7 control horses were confined to ...
Pulmonary and hepatic lesions caused by the dehydropyrrolizidine alkaloid-producing plants Crotalaria juncea and Crotalaria retusa in donkeys. The effects and susceptibility of donkeys to Crotalaria juncea and Crotalaria retusa poisoning were determined at high and low doses. Seeds of C. juncea containing 0.074% of dehydropyrrolizidine alkaloids (DHPAs) (isohemijunceines 0.05%, trichodesmine 0.016%, and junceine 0.008%) were administered to three donkeys at 0.3, 0.6 and 1 g/kg body weight (g/kg) daily for 365 days. No clinical signs were observed and, on liver and lung biopsies, the only lesion was a mild liver megalocytosis in the donkeys ingesting 0.6 and 1 g/kg/day. Two other donkeys that received daily doses of 3 and 5 g seed/...
Transit of micro-bubbles through the pulmonary circulation of Thoroughbred horses during exercise. It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with lower pulmonary artery pressures, enhanced right ventricular function and greater exercise capacity. In the exercising Thoroughbred horse, extraordinarily high cardiac outputs exert significant pulmonary vascular stresses. The aim of this study was to determine, using contrast echocardiography, whether Thoroughbred horses performing strenuous exercise developed pulmonary transit of agitated contrast microbubbles (PTAC). At res...
The effects of pulse-delivered inhaled nitric oxide on arterial oxygenation, ventilation-perfusion distribution and plasma endothelin-1 concentration in laterally recumbent isoflurane-anaesthetized horses. Anaesthetized horses commonly become hypoxaemic due to ventilation/perfusion (V·A/Q·) mismatch and increased pulmonary shunt fraction (Qs·/Qt·). Pulse-delivered inhaled nitric oxide may improve oxygenation but may increase plasma concentration of the potent vasoconstrictor, endothelin-1 (ET-1). Objectives: Study 1) compare arterial oxygen concentration (PaO2) and saturation (SaO2), calculated Qs·/Qt· and ET-1 concentration; and Study 2) assess V·A/Q· matching and measured Qs·/Qt· in isoflurane-anaesthetized horses in left lateral recumbency receiving pulse-delivered inhaled nitric ox...
Distribution of venous remodeling in exercise-induced pulmonary hemorrhage of horses follows reported blood flow distribution in the equine lung. Exercise-induced pulmonary hemorrhage (EIPH), which has been reported in humans and a variety of domestic animals following strenuous exercise, is most often documented in racehorses. Remodeling of pulmonary veins (VR) in equine EIPH was recently described, suggesting that it contributes to the pathogenesis of the disease. The cause of VR is unknown. We tested the hypothesis that the development of VR follows pulmonary blood flow distribution, preferentially occurring in the caudodorsal lung region. Furthermore, we hypothesized that VR underpins development of the other lesions of EIPH patholo...
Efficacy of mass antimicrobial treatment of foals with subclinical pulmonary abscesses associated with Rhodococcus equi. Mass antimicrobial treatment of foals with small subclinical ultrasonographic pulmonary lesions is empirical practice on many farms with endemic disease caused by Rhodococcus equi. Objective: Mass antimicrobial treatment of foals with subclinical ultrasonographic pulmonary lesions is unnecessary. Methods: One hundred and eight foals on a farm endemic for infections caused by R. equi. Methods: Controlled, randomized, and double-blinded prospective study. Foals with ultrasonographic evidence of pulmonary abscesses 5.0-10 cm in diameter (n = 108) were randomly allocated in 5 treatment groups: (1)...
Respiratory responses to exercise in the horse. Horses are elite athletes when compared with other mammalian species. In the latter, performance is limited by cardiovascular or musculoskeletal performance whereas in athletic horses it is the respiratory system that appears to be rate limiting and virtually all horses exercising at high intensities become hypoxaemic and hypercapnoeic. This is due to both diffusion limitation and a level of ventilation inadequate for the metabolic level that enables horses to exercise at these intensities. In conjunction with these blood gas changes, total pulmonary resistance increases and the work of breath...
Pharmacokinetics of macrolides in foals. Macrolides are used for treatment of pneumonia and extrapulmonary conditions caused by Rhodococcus equi. In foals, macrolides have an extraordinary capacity to accumulate in different lung tissue compartments. These drugs show unique pharmacokinetic features such as rapid and extensive distribution and long persistence in pulmonary epithelial lining fluid (PELF) and bronchoalveolar lavage (BAL) cells from foals. This article reviews the pharmacokinetic characteristics of erythromycin, azithromycin, clarithromycin, tulathromycin, telithromycin, gamithromycin, and tilmicosin in foals, with empha...
Pulmonary intravascular macrophages as proinflammatory cells in heaves, an asthma-like equine disease. Heaves, an obstructive neutrophilic airway inflammation of horses, is triggered by dust components such as endotoxin and has similarities to human asthma. Pulmonary intravascular macrophages (PIMs) increase horses' sensitivity to endotoxin-induced lung inflammation; however, their role in an airborne pathology remains unknown. Therefore, we investigated the role of PIMs in the development of heaves in horses. Clinical and inflammatory responses were evaluated following induction of heaves by moldy hay exposure and PIM depletion with gadolinium chloride (GC). Mares (N = 9) were exposed to four ...
Pulsed delivery of inhaled nitric oxide counteracts hypoxaemia during 2.5 hours of inhalation anaesthesia in dorsally recumbent horses. The study aimed to investigate the effect of varying pulse lengths of inhaled nitric oxide (iNO), and 2.5 hours of continuous pulse-delivered iNO on pulmonary gas exchange in anaesthetized horses. Methods: Experimental study. Methods: Six Standardbred horses. Methods: Horses received acepromazine, detomidine, guaifenesin, thiopentone and isoflurane in oxygen, were positioned in dorsal recumbency and were breathing spontaneously. iNO was on average pulsed during the first 20, 30, 43 or 73% of the inspiration in 15 minute steps. The pulse length that corresponded to the highest (peak) partial pr...
Clinicopathologic observations on laryngoplasty failure in a horse. To report morphologic findings associated with laryngoplasty failure in a horse. Methods: Clinical report. Methods: A 9-year-old Thoroughbred cross gelding. Methods: Necropsy and histopathology were performed on a horse that died peracutely during anesthetic recovery after correction of a right dorsal displacement of the ascending colon. Three weeks earlier the horse had left laryngoplasty and ventriculocordectomy. Results: Dissection of the larynx revealed that the laryngoplasty suture had pulled through the muscular process of the left arytenoid cartilage, which appeared grossly normal. Hist...
Effect of potential therapeutic agents in reducing oxidative stress in pulmonary tissues of recurrent airway obstruction-affected and clinically healthy horses. To determine and compare the reactive oxygen and nitrogen species (ROS and RNS) in pulmonary tissues of horses affected with recurrent airway obstruction (RAO) and clinically healthy horses, and to evaluate the effectiveness of potential therapeutic agents in reducing ROS and RNS in the tissues of these horses. Objective: We hypothesised that RAO-affected horses would have high levels of reactive species and that the test agents would reduce them. The objectives were as follows: 1) to determine the level of ROS and RNS in pulmonary tissues (bronchial and arterial rings) of RAO-affected and cli...
Pulmonary Disease due to Mycobacterium tuberculosis in a Horse: Zoonotic Concerns and Limitations of Antemortem Testing. A case of pulmonary tuberculosis caused by Mycobacterium tuberculosis was diagnosed in a horse. Clinical evaluation performed prior to euthanasia did not suggest tuberculosis, but postmortem examination provided pathological and bacteriological evidence of mycobacteriosis. In the lungs, multiple tuberculoid granulomas communicating with the bronchiolar lumen, pleural effusion, and a granulomatous lymphadenitis involving mediastinal and tracheobronchial lymph nodes were found. Serologic response to M. tuberculosis antigens was detected in the infected horse, but not in the group of 42 potential...
Effect of strenuous exercise and ex vivo TLR3 and TLR4 stimulation on inflammatory gene expression in equine pulmonary leukocytes. The effects of strenuous exercise and ex vivo stimulation of TLR3 and TLR4 pathways on the expression of six inflammatory genes in equine pulmonary leukocytes were investigated. The genes tested were interferon-beta (IFN-β), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interferon gamma-induced protein 10 (IP-10), chemokine (c-c motif) ligand 5 (RANTES) and tumor necrosis factor-alpha (TNF-α). We hypothesized that strenuous exercise would modulate basal gene expression on one hand and modulate the response to bacterial lipopolysaccharide (LPS) and to polyinosinic:polycytidylic acid (Pol...
Effects of in vitro exposure to autologous blood and serum on expression of interleukin-8, interleukin-1β, and chemokine (C-X-C motif) ligand 2 in equine primary bronchial epithelial cell cultures. To examine the effects of in vitro exposure to solutions of autologous horse blood (AHB) and autologous horse serum (AHS) on expressions of selected cytokine genes in equine primary bronchial epithelial cell (BEC) cultures and to contrast these responses to those induced in BEC cultures by endotoxin and hay dust. Methods: BEC cultures established from bronchi of 6 healthy horses. Methods: 5-day-old BEC cultures were treated with PBS solution, AHB (2 concentrations), AHS, hay dust solution, and lipopolysaccharide solution for 24 hours. Gene expressions of interleukin (IL)-8, IL-1β, chemokine (...
Profiling of differentially expressed genes using suppression subtractive hybridization in an equine model of chronic asthma. Gene expression analyses are used to investigate signaling pathways involved in diseases. In asthma, they have been primarily derived from the analysis of bronchial biopsies harvested from mild to moderate asthmatic subjects and controls. Due to ethical considerations, there is currently limited information on the transcriptome profile of the peripheral lung tissues in asthma. Objective: To identify genes contributing to chronic inflammation and remodeling in the peripheral lung tissue of horses with heaves, a naturally occurring asthma-like condition. Methods: Eleven adult horses (6 heaves-af...
