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.
Williams KJ, Derksen FJ, de Feijter-Rupp H, Pannirselvam RR, Steel CM, Robinson NE.Exercise-induced pulmonary hemorrhage (EIPH) is common in horses following intense exertion, occurring in up to 75% of racing Thoroughbreds and Standardbreds. In spite of this, the pathogenesis of EIPH is poorly understood. In 7 racing Thoroughbred horses with EIPH, 6 sections were collected from the left and right lung, representing the cranial, middle, and caudal region of the dorsal and ventral lung (84 sites total). Grossly, both right and left lungs had numerous dark brown to blue-black foci along the caudodorsal visceral pleura. Tissue sections were stained with hematoxylin-eosin, Masson...
Norman TE, Chaffin MK, Perris EE, Edwards JF, David JB, Cohen ND, Reuss S.This report involves 6 cases in which medical records and post mortem findings were reviewed leading to the diagnosis of massive pulmonary thromboembolism (MPTE). All horses were mature and MPTE has not been recognised previously as a sequel to generalised systemic illness in mature horses. The clinical data and pathological findings of the cases are reported and the authors conclude that MPTE is an uncommon but important complication of medical and surgical disorders in mature horses. In 3 of the cases, the condition was nonfatal suggesting that some horses having developed PTE survive and th...
Bell SA, Drew CP, Wilson WD, Pusterla N.Idiopathic chronic eosinophilic pneumonia of horses is incompletely described. Objective: To describe the physical examination, clinicopathologic, histopathologic, and radiographic features and response to corticosteroid treatment of idiopathic chronic eosinophilic pneumonia of horses. Methods: Seven horses with eosinophilic pneumonia. Methods: Retrospective, descriptive study. Results: Anamnesis, clinical signs, and clinicopathologic and radiologic findings in 7 adult horses with histologically confirmed eosinophilic pneumonia were reviewed. The horses were examined for signs of chronic respi...
Gehlen H, Haubold A, Rohn K, Stadler P.In the present study we examined, if in Icelandic horses an increase in heart and/ or breathing rate is physiological and breed dependend or a sign of a pulmonary or cardiac disease. Therefore we examined 37 Icelandic horses with the prereport of being healthy. During clinical lung examination four horses showed symptoms of a pulmonary disease like increased breathing rate and enforced breathing at rest. These horses were excluded from the study. The other 33 horses were clinically normal. 17 of these horses were unridden (untrained) and 16 horses were regularly worked (trained). After clinica...
Kawata H, Kishimoto H, Iwai S, Ishimaru K, Saito T, Kayatani F, Inamura N, Hamamichi Y, Kawada Y, Nasuno S, Maekawa S.We assessed the effect of reconstructing the pulmonary artery during arterial switch surgery for transposition of the great arteries on late pulmonary stenosis. Sixty-five patients who underwent Lecompte procedure between September 1991 and December 2006 were divided, by the procedure used chronologically to reconstruct the pulmonary artery, into group XP (single pantaloon patch with equine pericardium, n = 11), group P (direct reconstruction, n = 47), and group AP (single pantaloon patch with fresh autopericardium, n = 7). Outcome and pulmonary stenosis on the most recent ultrasound cardiogra...
DeLuca L, Erb HN, Young JC, Perkins GA, Ainsworth DM.Chemokine expression in airway epithelium and bronchoalveolar lavage fluid (BALF) cells of horses with recurrent airway obstruction (RAO) is increased. Objective: For RAO-affected horses that are stabled and fed a pelleted ration, the addition of oral dexamethasone further improves pulmonary function and reduces inflammatory gene expression in pulmonary cells. Methods: Twelve RAO-affected horses. Methods: In a randomized cross-over experiment, the effect of feeding pellets in lieu of hay to stabled, RAO-affected horses was compared with the effect of feeding pellets and administering a 21-day ...
Grubb TL, Högman M, Edner A, Frendin JH, Heinonen E, Malavasi LM, Frostell CG, Ryden A, Alving K, Nyman GC.To assess physiologic responses and plasma endothelin (ET)-1 concentrations associated with abrupt cessation of nitric oxide (NO) inhalation in isoflurane-anesthetized horses. Methods: 6 healthy adult Standardbreds. Methods: Horses were anesthetized with isoflurane in oxygen and placed in dorsal recumbency. Nitric oxide was pulsed into the respiratory tract for 2.5 hours, and then administration was abruptly discontinued. Just prior to commencement and at cessation of NO administration, and at intervals during a 30-minute period following cessation of NO inhalation, several variables including...
Pusterla N, Jones ME, Mohr FC, Higgins JK, Mapes S, Jang SS, Samitz EM, Byrne BA.A case of fatal pulmonary hemorrhage in a 6-year-old American Paint mare with a 2-week history of intermittent coughing, fever, and epistaxis is described. Significant macroscopic abnormalities at postmortem examination were restricted to the respiratory system, and microscopically, severe pulmonary hemorrhage with suppurative bronchopneumonia was found. Actinobacillus equuli subsp. haemolyticus was cultured from a transtracheal wash performed antemortem as well as from the lungs at necropsy. The presence of airway-associated hemorrhage in conjunction with bacterial bronchopneumonia suggested ...
Riihimäki M, Raine A, Art T, Lekeux P, Couëtil L, Pringle J.The aim of this study was to investigate mRNA levels of cytokines in bronchial epithelium in horses with recurrent airway obstruction (RAO) during acute crisis and remission. Additionally, cytokine mRNA levels in endobronchial biopsies and bronchoalveolar lavage (BAL) cells were compared. Seven RAO horses were examined while in respiratory crisis following provocation and again while in remission after 2 months on pasture, during which time six healthy horses on pasture were also examined. Quantitative real-time PCR (RT-PCR) was used to assess mRNA expression for cytokines IL-5, IL-6, IL-8, IL...
Dunkel B, Rickards KJ, Page CP, Cunningham FM.Platelet activation occurs in human obstructive airway diseases and in laboratory animal models. However, there is limited evidence that platelets may be involved in equine recurrent airway obstruction (RAO) and other inflammatory diseases. This study investigated whether platelet activation also occurred in RAO. Objective: Platelet function is altered in ponies with active RAO. This alteration can be detected ex vivo by measuring platelet adhesion. Methods: An in vitro platelet adhesion assay measuring acid phosphatase (AcP) activity colorimetrically was adapted for use with equine platelets ...
Ainsworth DM, Wagner B, Erb HN, Young JC, Retallick DE.To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on cytokine expression in pulmonary mononuclear cells isolated from healthy horses and horses with recurrent airway obstruction (RAO). Methods: 8 RAO-affected and 7 control horses (experiment 1) and 6 of the RAO-affected and 5 of the control horses (experiment 2). Methods: Bronchoalveolar lavage cells were isolated from horses that had been stabled and fed dusty hay for 14 days. Pulmonary mononuclear cells were incubated for 24 (experiment 1) or 6 (experiment 2) hours with PBS solution or...
Williams KJ, Maes R, Del Piero F, Lim A, Wise A, Bolin DC, Caswell J, Jackson C, Robinson NE, Derksen F, Scott MA, Uhal BD, Li X, Youssef SA, Bolin SR.Pulmonary fibrosis and interstitial lung disease are poorly understood in horses; the causes of such conditions are rarely identified. Equine herpesvirus 5 (EHV-5) is a gamma-herpesvirus of horses that has not been associated with disease in horses. Pathologic and virologic findings from 24 horses with progressive nodular fibrotic lung disease associated with EHV-5 infection are described and compared with 23 age-matched control animals. Gross lesions consisted of multiple nodules of fibrosis throughout the lungs. Histologically, there was marked interstitial fibrosis, often with preservation ...
Venner M, Reinhold B, Beyerbach M, Feige K.The prophylactic application of azithromycin to prevent pulmonary abscesses in foals was evaluated on a stud with endemic Rhodococcus equi pneumonia. Forty-five foals served as untreated controls in two groups. Twenty-five foals were given azithromycin (10mg/kg) orally once daily for 4 weeks. The foals were examined once a week from birth to the age of 5 months. If clinical signs or leucocytosis were noted and pulmonary sonographic findings (diameter >10 mm) were observed, the diagnosis of abscessing pneumonia was made. The prevalence of pulmonary abscesses was similar in the control groups (3...
Cunningham FM, Dunkel B.Recurrent airway obstruction (RAO) and insect bite hypersensitivity (IBH) are allergic conditions that are commonly encountered in the horse. Whilst complete allergen avoidance is an effective management strategy for both diseases, this may not be achievable in all cases and treatment options are therefore required. The inflammatory response is the main therapeutic target for glucocorticoids given to horses with RAO and severe cases of IBH, whilst the bronchodilators used in RAO primarily target airway smooth muscle. Such drugs are effective in most but not all individuals and there may be unw...
Riihimäki M, Lilliehöök I, Raine A, Berg M, Pringle J.The aim of this study was to assess clinical signs and altered pulmonary cell expression of cytokines related to eosinophil kinetics in horses with pulmonary eosinophilia. Pulmonary eosinophilia was detected by bronchoalveolar lavage (BAL) in a group of standardbreds in training. Horses had detailed clinical examination, bronchoscopy, endobronchial biopsy and BAL on three occasions at approximately 6 month intervals. During the second sampling period BAL eosinophils were significantly elevated (p>0.010), with five horses having from 5% to 37% eosinophils in BAL. Neither detailed clinical ex...
Miskovic M, Couëtil LL, Thompson CA.The effects of long-term environmental management on airway obstruction and inflammation in horses with recurrent airway obstruction (RAO) are unknown. Objective: Horses with RAO maintained in low-dust environments have persistent airway obstruction and neutrophilic inflammation. Methods: Study horses were treated for RAO and then maintained in low-dust environments with no medical management. Horses were classified into 3 groups by years after diagnosis: 1 year (time 1, n = 9), 2-3 years (time 2, n = 7), and 5-6 years (time 3, n = 8). The comparison groups were age-matched healthy horses. Met...
Muscatello G, Leadon DP, Klayt M, Ocampo-Sosa A, Lewis DA, Fogarty U, Buckley T, Gilkerson JR, Meijer WG, Vazquez-Boland JA.Infection with Rhodococcus (Corynebacterium) equi is a well-recognised condition in foals that represents a consistent and serious risk worldwide. The condition manifests itself primarily as one of pulmonary abscessation and bronchitis, hence the terminology of 'rattles' derived from its most obvious clinical sign, frequently terminal when first identified. This review addresses the clinical manifestation, bacteriology and pathogenesis of the condition together with recent developments providing knowledge of the organism in terms of virulence, epidemiology, transmission and immune responses. E...
Joubert P, Cordeau ME, Boyer A, Silversides DW, Lavoie JP.Heaves, also known as recurrent airway obstruction, is a common condition of horses characterised by pulmonary neutrophilia and reversible airway obstruction. This study evaluated the role of neutrophils in producing cytokines and chemokines that might be involved in the recruitment and activation of inflammatory cells in horses with heaves. Peripheral neutrophils were isolated from heaves-affected (n = 9) and control (n = 4) horses before and after 5 h of natural inhalation challenge. Expression of mRNA of two pro-inflammatory cytokines, tumour necrosis factor (TNF)-alpha and interleukin (IL)...
Derksen FJ, Williams KJ, Uhal BD, Slocombe RF, de Feijter-Rupp H, Eberhart S, Berney C, Robinson NE.Exercise-induced pulmonary haemorrhage (EIPH) occurs in the majority of horses performing strenuous exercise. Associated pulmonary lesions include alveolar and airway wall fibrosis, which may enhance the severity of EIPH. Further work is required to understand the pulmonary response to blood in the equine airways. Objective: To confirm that a single instillation of autologous blood into horse airways is associated with alveolar wall fibrosis, and to determine if blood in the airways is also associated with peribronchiolar fibrosis. Methods: Paired regions of each lung were inoculated with bloo...
Evans DL.This review addresses the physiology of performance horses in the context of functional tests aimed at assisting clinicians in the search for explanations of the individual's limitations, actual or perceived as below expectation. The intention is to assist clinicians who are faced frequently by owners or trainers seeking explanations for poor performance; and for research workers as a basis on which to proceed in their search for new methodologies, particularly those that can be applied in the field as for treadmill exercise. The review sets out fundamental physiological pathways, the entailme...
Huang H, Lavoie-Lamoureux A, Moran K, Lavoie JP.Little is known concerning the possible contribution of T helper 2 (Th2)-type cytokines to the recruitment of neutrophils into the lung tissue. In the present study, endothelial cells from equine pulmonary arteries were cultured in the presence of recombinant equine (re) IL-4 and reIL-5, and the cytokine mRNA expression of molecules implicated in the chemotaxis and migration of neutrophils was studied using real-time RT-PCR. The functional response of reIL-4-induced endothelial cell stimulation on neutrophil migration was also studied using a chemotaxis chamber. ReIL-4 either increased the exp...
Womble A, Giguère S, Lee EA.The objective of this study was to determine the disposition of orally administered doxycycline in foals. Six healthy 4- to 8-week-old foals were used. Doxycycline was administered to each foal via the intragastric (IG) route at dosages of 10 and 20 mg/kg, in a cross-over design. After the first 10 mg/kg dose, five additional doses were administered at 12-h intervals. A microbiological assay was used to measure doxycycline activity in serum, urine, peritoneal fluid, synovial fluid, cerebrospinal (CSF), pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. Following adminis...
Holbrook TC, Dechant JE, Crowson CL.A 523 kg Quarter Horse was anesthetized for unilateral eye enucleation. The anesthetic period was unremarkable. During anesthetic recovery the cap on the jugular venous catheter became dislodged. Clinical signs of pulmonary edema associated with moderate arterial hypoxemia subsequently developed. Although pulmonary edema resolved with medical therapy, the day following anesthetic recovery, clinical signs of vestibular disease and blindness developed. Treatment included nasal oxygen insufflation, flunixin meglumine, furosemide, dexamethasone, thiamine, dimethylsulfoxide, antimicrobials, and phe...
Johansson AM, Gardner SY, Atkins CE, LaFevers DH, Breuhaus BA.Recurrent airway obstruction (RAO) is common in horses. Although pulmonary artery (PA) pressure increases during RAO, cardiac function in horses with RAO has received limited attention. Objective: The purpose of this study was to noninvasively determine the cardiovascular effects of acute pulmonary obstruction (APO) in horses with RAO and their reversibility. Methods: Five geldings with RAO, inducible by exposure to moldy hay, were studied. Methods: Pulmonary mechanics, echocardiography, serum troponin I concentrations, arterial blood gases, and hematocrit were obtained before and after 7 days...
Padilla DJ, Epp TS, McDonough P, Marlin DJ, Erickson HH, Poole DC.During high intensity exercise, the very high pulmonary artery pressure (Ppa) experienced by Thoroughbred horses is considered a major factor in the aetiology of exercise-induced pulmonary haemorrhage (EIPH). Recently, endothelin-1 (ET-1), a potent vasoconstrictive hormone, has been found to increase Ppa in horses at rest via binding to its ET-1A receptor subtype. In addition, plasma concentrations of ET-1 are increased in horses during and after high intensity exercise. Objective: If ET-1 increases Ppa during exercise in the horse, administration of a specific ET-1A antagonist would decrease ...
Vengust M, Staempfli H, Viel L, Heigenhauser G.Horses develop high pulmonary pressures during exercise, which force fluid out of pulmonary capillaries. Specific airway diseases in horses, especially those associated with hypoxaemia, hypercapnoea and acidosis may influence pulmonary haemodynamics and pulmonary interstitial fluid equilibrium. Objective: This study was designed to determine fluid flux (J(V-A) l/min) across the lung in exercising horses treated chronically with acetazolamide. Methods: Six horses were exercised on a treadmill until fatigue without (Con) and with chronic carbonic anhydrase (CA) inhibition (AczTr) and associated ...
Khol-Parisini A, van den Hoven R, Leinker S, Hulan HW, Zentek J.A crossover feeding trial was performed with 9 horses suffering from recurrent airway obstruction (RAO). The study aimed to determine whether ingestion of sunflower oil (SFO), rich in linoleic acid, or seal blubber oil (SBO), a source of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs), changes the fatty acid (FA) ratios in plasma and leukocyte membrane phospholipids (PLs) or the leukocyte numbers or proportions of cell types in the airways. We also investigated diet-related changes in respiratory rate, maximum change in pleural pressure (deltaPpl(max)), dynamic compliance (C(dyn)...
McLennan MW, Kelly WR.A case of hypertrophic osteopathy is described in a mare with a vague history of abdominal discomfort over the preceding 12 months. Bony swellings were obvious in the pastern area of both forelegs. There was a dysgerminoma of the left ovary that had metastasised to several abdominal lymph nodes and had infiltrated the posterior vena cava. There was no gross thoracic involvement although there was histologic evidence of tumour metastasis in pulmonary arterioles.
Weixler VHM, Kuschnerus K, Romanchenko O, Ovroutski S, Cho MY, Berger F, Sigler M, Sinzobahamvya N, Photiadis J, Murin P.The aim was to report mid-term performance of decellularized equine pericardium used for repair of various congenital heart defects in the pediatric population. Methods: A retrospective review of all patients undergoing patch implantation between 2016 - 2020 was performed. Patch quality, surgical handling, hemostasis and early patch-related complications were studied on all patients. Mid-term performance was observed in patients with ≥12 months follow-up and intact patch at discharge (without reoperation/stent implantation). Results: A total of 201 patients with median age of 2.5 years [inte...
Lavoie JP, Pascoe JR, Kurpershoek CJ.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) ...
Venugopal C, Mariappan N, Holmes E, Kearney M, Beadle R.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...
Gerger H.Several forms of chronic pulmonary disease in the horse can be differentiated, to some extent, by simple means within the scope of every clinician. The proposed diagnostic system permits more precise diagnoses, which are supported by histopathological evidence. Such diagnoses justify a reasonably accurate prognosis of a horse's chance of recovery. They also have been used as a basis for constructing a pathogenetic model.
Among the factors involved in the pathogenesis of chronic pulmonary disease, ageing has probably been overrated.
Climatic changes influence the symptomatology and the co...
Ainsworth DM, Appleton JA, Eicker SW, Luce R, Julia Flaminio M, Antczak DF.The effect of strenuous exercise on the mRNA concentrations of interleukin-12p35 subunit (IL-12p35), interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in equine pulmonary and peripheral blood mononuclear cells (PBMCs) was investigated. We hypothesized that strenuous exercise would suppress the expression of IL-12p35, IFN-gamma and augment the expression of IL-4. Eleven horses were randomly divided into two groups, a stall-confined control group (n=5) and an exercise-conditioned treatment group (n=6). Bronchoalveolar and PBMCs were obtained from horses in the treatment group prior to the co...
Bedenice D, Heuwieser W, Brawer R, Solano M, Rand W, Paradis MR.A total of 207 thoracic radiographs obtained from 128 foals were evaluated to assess the impact of pulmonary radiographic pattern, distribution, and severity of pulmonary changes on short-term survival of neonatal foals. The association between selected clinical variables and the radiographic manifestation of neonatal respiratory disease was also investigated. The evaluation of interstitial and alveolar-interstitial radiographic patterns within the caudodorsal, caudoventral, and cranioventral lung regions proved to be highly reliable between viewers in the study. A diagnosis of systemic inflam...
Mignot CC, Pirottin D, Farnir F, de Moffarts B, Molitor C, Lekeux P, Art T.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...
Scheuch E, Spieker J, Venner M, Siegmund W.The long-acting antibiotic tulathromycin is on the marked for treatment of pulmonary infection of cattle, swine and horses. To measure disposition and distribution of tulathromycin in foals, a high throughput method was developed for horse plasma (calibration range: 0.006-0.8 microg/mL) and broncho-alveolar cells (calibration range: 0.1-4.0 microg/10(9)cells) using tandem mass spectrometry. Tulathromycin was extracted from plasma and broncho-alveolar fluid using cation exchange cartridges with acetonitrile/ammonia (95:5, v/v). The chromatography was performed isocratically with a mobile phase ...
MacEachern KE, Smith GL, Nolan AM.Equine endothelial cells were isolated from the pulmonary artery by enzymatic digestion and grown to confluency. The cells were characterised by positive immunofluorescent staining for von Willebrand factor and NADPH-diaphorase staining for nitric oxide synthase. Measurements of endothelins indicated that there were significant release rates from the cells for up to six hours. Measurements of intracellular calcium concentration showed that the application of bradykinin caused a transient increase in calcium concentration with similar characteristics to those observed in other endothelial cell ...
Lavoie JP, Phan ST, Blais D.To evaluate the effects of detomidine and butorphanol in combination on respiratory function in horses and to determine whether these effects are more severe in horses with pre-existing respiratory dysfunction, Methods: Pulmonary function testing and arterial blood gas analyses were performed before and after administration of a combination of detomidine (10 micrograms/kg of body weight, i.v.) and butorphanol (20 micrograms/kg, i.v.). Methods: 5 horses with chronic obstructive pulmonary disease and 5 horses free of respiratory disease (controls). Methods: Flow rates were obtained from a pneumo...
Khanna AK, McDonell WN, Dyson DH, Taylor PM.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 ...
Manohar M, Goetz TE.The present study examined whether Thoroughbred horses performing strenuous exercise exhibit intrapulmonary arteriovenous shunting that may contribute to the observed arterial hypoxemia. Experiments were carried out on seven healthy, exercise-trained Thoroughbreds at rest, maximal exercise (galloping at 14 m/s on a 3.5% uphill grade for 120 s), and submaximal exertion (8 m/s on a 3.5% uphill grade for 150 s). Along with blood gas/hemodynamic parameters, intrapulmonary arteriovenous shunting was studied by injecting 15-microm-diameter microspheres, labeled with different stable isotopes, into t...
Erickson BK, Seaman J, Kubo K, Hiraga A, Kai M, Yamaya Y, Wagner PD.Previous work has shown that replacing N2 in air with He at the same inspired O2 fraction reduces the exercise-induced alveolar-arterial PO2 difference (AaPO2) in horses but has provided no mechanism explaining this effect. We sought to distinguish among possible causes by using the multiple inert gas elimination technique. Six horses were studied on a high-speed treadmill while they breathed either ambient air or normoxic He-O2. O2 uptake reached 138.0 ml.min-1.kg-1 and was not affected by He-O2. Temperature-corrected arterial PO2 was 76.7 Torr (air) and 86.9 Torr (He-O2) (P < 0.01). Corre...
Erickson BK, Seaman J, Kubo K, Hiraga A, Kai M, Yamaya Y, Wagner PD.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 ...
Jacobson GA, Raidal S, Robson K, Narkowicz CK, Nichols DS, Haydn Walters E.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...
Brown DR, Forster HV, Greene AS, Lowry TF.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...
Jean D, Vrins A, Lavoie JP.To determine temporal variations of pulmonary function in horses without respiratory tract disease (controls) and horses with chronic obstructive pulmonary disease (COPD) and determine whether reversibility of airway obstruction after environmental control can be predicted by response to atropine administration. Methods: 7 COPD-affected and 5 control horses. Methods: Pulmonary function testing was performed monthly during 3 consecutive months, daily for 5 consecutive days, and at 6-hour intervals for 24 hours before and after administration of atropine (0.02 mg/kg of body weight, i.v.) and aft...
Pantaleon LG, Furr MO, McKenzie HC, Donaldson L.Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. Objective: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid ...
Manohar M, Goetz TE.Exercise-induced pulmonary hemorrhage (EIPH) is a common occurrence in racehorses. The objective of this study was to compare pulmonary vascular pressures of healthy Thoroughbred horses with and without postexertion endoscopically detectable fresh blood in the trachea. The nasopharynx, larynx, and trachea (down to the carina) of horses were examined weekly with an endoscope 55-60 min postexertion, and the diagnosis of EIPH was confirmed by the presence of fresh blood in the trachea. Measurements of heart rate and right atrial, pulmonary arterial, and pulmonary arterial wedge pressures were mad...
Raidal SL, Love DN, Bailey GD, Rose RJ.The effect of strenuous exercise on the functional capacity of pulmonary alveolar macrophages (PAM) and bronchoalveolar lavage-derived lymphocytes was determined in eight horses prior to and after 7 weeks of training. Strenuous exercise had no effect on the total cell count or the percentage of live cells in bronchoalveolar lavage (BAL) samples prior to or following training. However, training was associated with a significant increase in the total cell count of pre-exercise BAL samples and a significant reduction in the percentage of live cells in post-exercise samples. Strenuous exercise was...
Issouf M, Vargas A, Boivin R, Lavoie JP.Airway wall remodeling, including hyperplasia and hypertrophy of smooth muscle (ASM) cells leading to an increased smooth muscle mass, is considered central to asthma. However, molecular pathways responsible for ASM remodeling remain poorly understood. MicroRNAs (miRNAs) have emerged as key regulators of inflammatory and repair processes affecting the lungs and can downregulate protein expression by inhibiting target mRNA translation. We therefore hypothesized that miRNAs are involved in ASM remodeling in asthma by modulating ASM proliferation. We have analyzed the expression of miRNAs in bron...
Langsetmo I, Meyer MR, Erickson HH.Exercise-induced pulmonary haemorrhage (EIPH) is characterised by blood in the airways after strenuous exercise and results from stress failure of the pulmonary capillaries. The purpose of this experiment was to establish a threshold value of transmural pulmonary arterial pressure at which haemorrhage occurs in the exercising horse. Five geldings, age 4-14 years, were run in random order once every 2 weeks at 1 of 4 speeds (9, 11, 13, 15 m/s); one day with no run was used as a control. Heart rate, pulmonary arterial pressure and oesophageal pressure were recorded for the duration of the run. T...
McKane SA, Slocombe RF.Histological studies of exercise-induced pulmonary haemorrhage (EIPH) reveals inflammatory infiltrates within areas of lung that contain haemorrhage. This has resulted in the hypothesis that pulmonary inflammation could cause EIPH or contribute to an increased risk or severity of EIPH. Objective: To determine whether experimentally-induced pulmonary inflammation predisposes the lung to haemorrhage during exercise, by evaluating the bronchoalveolar lavage (BAL) cytology of normal and inflamed regions of lung following high speed treadmill exercise. Methods: Transendoscopic airway inoculations o...
Waldschmidt I, Pirottin D, Art T, Audigié F, Bureau F, Tosi I, El Abbas S, Farnir F, Richard E, Dupuis MC.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...
da Silva KM, Otaka JNP, Gonçalves CAP, Silva EGA, de Alencar NX, Lessa DAB.The respiratory system is essential for health and high athletic performance in horses. Respiratory diseases have been recognized as having a major impact on training equine animals and are commonly cited as the second most common cause of wasted training time. Inflammatory airway disease (IAD) is an important cause of poor performance in young racehorses. Exercise-induced pulmonary hemorrhage (EIPH) is considered a major issue for the equine industry because of its high prevalence and association with reduced athletic performance. In Brazil, polo is a growing equestrian sport, but studies on ...
Hinchcliff KW, Muir WW.Furosemide, a diuretic, is frequently administered to horses for the prophylaxis of exercise-induced pulmonary hemorrhage and the treatment of a number of clinical conditions, including acute renal failure and congestive heart failure. Furosemide increases the rate of urinary sodium, chloride, and hydrogen ion excretion. Plasma potassium concentration decreases after furosemide administration but urinary potassium excretion in horses is minimally affected. Renal blood flow increases after furosemide administration. Systemically, furosemide increases venous compliance and decreases right atrial...
Carrasco L, Sánchez C, Gómez-Villamandos JC, Laviada MD, Bautista MJ, Martínez-Torrecuadrada J, Sánchez-Vizcaíno JM, Sierra MA.African horse sickness (AHS) is a disease of equids, characterized by severe pulmonary oedema and caused by an orbivirus. To determine the role of pulmonary intravascular macrophages (PIMs) in the development of pulmonary microvascular changes in this disease, five horses were given an intravenous inoculation of 10(6)TCID50of serotype 4 of AHS virus. Viral replication was detected in endothelial cells, PIMs, interstitial macrophages and fibroblasts. Alveolar and interstitial oedema, and changes in pulmonary microvasculature, consisting mainly of the sequestration of neutrophils and the formati...
Longworth KE, Smith BL, Staub NC, Steffey EP, Serikov VB.To determine whether a detergent can prevent most of the early effects of i.v. infusion with Escherichia coli endotoxin (< 100 ng/kg of body weight) in horses: marked pulmonary hypertension, acute leukopenia, and fever. Methods: 8 healthy adult horses (4 male, 4 female), 415 to 615 kg. Methods: Control and detergent experiments were performed in each horse while it was awake but sedated. In control experiments, 10 to 100 ng of E coli endotoxin/kg was given. In detergent experiments, 100 mg of detergent/kg was given 1 hour before injecting endotoxin, similar to the control experiments. Resul...
