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Topic:Lung Health
Lung health in horses encompasses the study of respiratory system function, disease, and maintenance in equine species. The equine respiratory system is vital for oxygen exchange and plays a significant role in overall health and athletic performance. Conditions affecting lung health include inflammatory airway disease (IAD), recurrent airway obstruction (RAO), and exercise-induced pulmonary hemorrhage (EIPH). These conditions can impact a horse's respiratory efficiency and performance capabilities. Research in this area often focuses on understanding the pathophysiology, diagnosis, and management of respiratory diseases, as well as the impact of environmental factors on lung function. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, diagnostic approaches, and therapeutic strategies related to lung health in horses.
Organic dust exposure increases mast cell tryptase in bronchoalveolar lavage fluid and airway epithelium of heaves horses. Mast cell degranulation is believed to act as a key event in initiating and maintaining airway response to allergen challenge in human asthma. It is hypothesized that the mast cell may play a similar role in equine heaves, which shares many similarities with occupational dust-induced asthma. Objective: The aim of this study was to quantify the mast cell proteinase tryptase in bronchoalveolar lavage fluid (BALF) from control and heaves-susceptible horses and to investigate tryptase mRNA and protein expression in pulmonary mast cells. Methods: Equine BALF tryptase concentrations were determined ...
Lung function and airway cytologic profiles in horses with recurrent airway obstruction maintained in low-dust environments. 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...
Equine recurrent airway obstruction does not alter airway muscarinic acetylcholine receptor expression and subtype distribution. In recurrent airway obstruction (RAO) or heaves, bronchospasm has been attributed to enhanced cholinergic activity. However, the expression and function of muscarinic acetylcholine receptors (mAChR) and their signaling components are not yet known. Thus, we examined the expression, subtype distribution and postreceptor signaling pathways of mAChR in the peripheral lung, bronchial and tracheal epithelia with the underlying smooth muscle from nine horses with RAO and 11 healthy control horses. In RAO horses, no significant segment-dependent alteration in mAChR density and subtype distribution (a...
Pulmonary response to airway instillation of autologous blood in horses. 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...
Thoracic percussion to determine the caudal lung border in healthy horses. The application of equine thoracic percussion has been ignored because of the availability of modern imaging techniques. Ultrasonography is a reliable tool in determining the caudal lung border of horses. The aim of the study was to compare percussion with ultrasonography to determine lung borders in horses. Objective: That thoracic percussion can detect the caudal lung border and that its accuracy is comparable with thoracic ultrasonography. Methods: Fifteen randomly chosen, healthy, Warmblood horses. Methods: The caudal lung border was detected by percussion and ultrasonography at the end of...
Evaluation of lung maturity by amniotic fluid analysis in equine neonate. The aim of this study was to gather useful new data for evaluation of lung maturity in the neonatal foal. Because equine neonatal intensive therapy is very expensive, a precocious diagnosis could help to express a prognosis and to offer a respiratory support early after birth, increasing the survival rate and reducing complications. Amniotic fluid was collected at parturition on n=18 mares. Lamellar bodies were isolated in the amniotic fluid and measured with transmission electron microscopy (TEM). Furthermore two tests on amniotic fluid that are commonly used in humane medicine were utilized:...
Effects of chronic acetazolamide administration on fluid flux from the pulmonary vasculature at rest and during exercise in horses. 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 ...
Cold air-induced late-phase bronchoconstriction in horses. Inspired air is warmed to body temperature and fully humidified by the upper airway mucosa under normal resting conditions. This conditioning process may not be completed by the upper airways during conditions of increased minute ventilation or when the inspired air is unusually cold, resulting in cooling and desiccation of lower respiratory surfaces. Excess heat and water loss from intrapulmonary airways is believed to be the provocative stimulus for exercise-induced bronchoconstriction (occurring immediately after exercise) and associated late phase airway obstruction (occurring a few hours ...
Effect of corticosteroid and bronchodilator therapy on bronchoalveolar lavage cytology following intrapulmonary blood inoculation. Intrapulmonary blood causes an inflammatory response. Modifying this inflammatory response may be useful in the treatment of exercise induced pulmonary haemorrhage (EIPH). Objective: To evaluate the efficacy of 3 treatments, an oral bronchodilator, inhaled steroid and oral steroid in modifying the cellular response to intrapulmonary blood inoculation. Methods: Experimental design was a randomised block divided into 4 experimental segments of 2 weeks. Eight normal horses were randomly assigned to pairs and treatments. Autologous blood was inoculated into the lungs on 4 occasions over an 8 week ...
Plethysmographic comparison of breathing pattern in heaves (recurrent airway obstruction) versus experimental bronchoconstriction or hyperpnea in horses. Horses with recurrent airway obstruction (heaves) are described as exhibiting "increased abdominal effort," but it is unknown whether this translates to an effective contribution to ventilation. Objective: We hypothesized that heaves is characterized by asynchrony between rib cage and abdominal motions, and that the abdominal component is the major contributor to ventilation. Methods: The rib cage versus abdominal motion in naturally occurring heaves (n = 15) was compared to controls at rest (n = 7) and during hyperpnea because of lobeline treatment, and the effects of histamine-induced bronch...
Reactivity of equine airways–a study on precision-cut lung slices. A study was performed to evaluate the use of precision-cut lung slices (PCLS) for studies on the contraction of equine airways. Lungs of 10 horses were taken to prepare PCLS of approximately 250 microm from equine lung tissue using a special microtome. The lung slices were cultured and the enclosed small airways were monitored using a microscope with coupled digital camera, which was used to determine the airway luminal area and diameter from digital images. As indicated by the beating of the ciliated epithelium and reactivity of airways on methacholine challenge, the tissue slices were found ...
Lung surfactant function and composition in neonatal foals and adult horses. Lung surfactant function and composition are varied and adapted to the specific respiratory physiology of all mammalian species. Objective: Lung surfactant function and composition are different in neonatal foals as compared to adult horses. Methods: Six adult horses, 7 term foals (<24 hours old), and 4 premature foals were used. Animals were part of the Auburn University teaching herd except for 3 client-owned premature foals. Methods: Bronchoalveolar lavage fluid (BALF) was obtained from all animals. Ultracentrifugation of cell-free BALF separated surfactant into crude surfactant pellets ...
Segment-dependent expression of muscarinic acetylcholine receptors and G-protein coupling in the equine respiratory tract. Muscarinic receptors are considered to be of comparable clinical importance in chronic obstructive pulmonary disease (COPD) in equines and in humans. At present, data are scarce on the expression and distribution of probable subtypes of these receptors and their signalling pathways in airway segments, including lung parenchyma and bronchial and tracheal epithelium with the underlying smooth muscle in horses. Specific [N-methyl-3H]scopolamine chloride ([3H]NMS) binding to all three tissues was saturable and of high affinity, with KD values ranging between 1.6+/-0.7 and 1.9+/-0.3 nmol/L. [3H]NMS...
Early onset airway obstruction in response to organic dust in the horse. Equine recurrent airway obstruction (RAO) has been used as a naturally occurring model of human asthma. However, it is unknown whether there is an early-phase response in RAO. The aim of this study was to determine whether exposure to organic dust induces immediate changes in lung function in RAO-affected horses, which could be mediated by airway mast cells. Six RAO-affected horses in remission and six control horses were challenged with hay-straw dust suspension by nebulization. Total respiratory resistance at 1 Hz, measured by forced oscillation, was increased from 0.62 +/- 0.09 cmH(2)O.l(-1...
Theophylline does not potentiate the effects of a low dose of dexamethasone in horses with recurrent airway obstruction. Theophylline has been shown to have corticosteroid-sparing effects for the treatment of human asthma. A similar effect, if present in horses, would allow diminishing the dose of corticosteroids administered to equine patients with inflammatory airway diseases. Objective: To evaluate whether theophylline potentiates the effects of a low dose of dexamethasone when treating horses with recurrent airway obstruction (RAO). Objective: Theophylline has steroid-sparing effects in horses with RAO. Methods: Ten mature mixed breed horses in clinical exacerbation of RAO were studied. Using an incomplete c...
Effects of the bronchoalveolar lavage procedure on lung function in horses with clinical exacerbation of recurrent airway obstruction. To evaluate whether bronchoalveolar lavage (BAL) alters respiratory mechanics of horses with recurrent airway obstruction (ie, heaves) over a 48-hour period. Methods: 6 horses affected with heaves. Methods: Horses were subjected to a complete BAL procedure, which included sedation with xylazine and butorphanol, intratracheal administration of lidocaine, and instillation and aspiration of two 250-mL boluses of saline (0.9% NaCl) solution through an endoscope (study 1). To evaluate the effects of saline solution, horses were subjected to the same procedure without saline solution instillation an...
Distribution of CCR3 mRNA expression in horse tissues. CCL11 (also known as eotaxin) is a very potent and selective mediator of eosinophil migration which exerts its effects through its receptor, CCR3. In this study we report the cloning of an equine CCR3 cDNA sequence and investigation of the localization of CCR3 mRNA expression in horse tissues. Equine CCR3 displayed high levels of sequence identity with CCR3 sequences in other species. RT-PCR analysis revealed the expression of CCR3 in colon, lung and spleen of normal horses. In situ hybridisation experiments indicated that expression of CCR3 mRNA in colon was predominantly in eosinophils and t...
Percutaneous lung biopsy in the horse: comparison of two instruments and repeated biopsy in horses with induced acute interstitial pneumopathy. The aim of the study reported here was to compare complications of lung biopsy in horses and the quality of the lung specimens after biopsy using the manual Tru-Cut biopsy needle (TC) and an automated biopsy needle (ABN). For experiment 1, lung biopsy was performed in 50 horses with one instrument on one side of the thorax, and then with the other instrument on the other side. Postmortem examination was performed in 20 of the 50 horses. Coughing was detected in 10 of 50 horses and epistaxis was observed in 6 of the 50 horses. Endoscopy revealed bleeding into the airways in 16 of 49 horses and ...
Cholesterol oxidase (ChoE) is not important in the virulence of Rhodococcus equi. To analyze further the role in virulence of the prominent cholesterol oxidase (ChoE) of Rhodococcus equi, an allelic exchange choE mutant from strain 103+ was constructed and assessed for virulence in macrophages, in mice, and in foals. There was no difference between the mutant and parent strain in cytotoxic activity for macrophages or in intra-macrophage multiplication. No evidence of attenuation was obtained in macrophages and in mice, but there was slight attenuation apparent in four intra-bronchially infected foals compared to infection of four foals with the virulent parent strain, based...
In vitro inhibition of matrix metalloproteinase activity in tracheal epithelial lining fluid from horses with recurrent airway obstruction. To evaluate inhibitory effects of synthetic matrix metalloproteinase (MMP) inhibitors in vitro on gelatinolytic and collagenolytic activities in tracheal epithelial lining fluid (TELF) of horses with recurrent airway obstruction (RAO). Methods: 10 horses with RAO and 5 healthy control horses. Methods: Substrate-based functional assays, collagen I and gelatin degradation, were used to measure endogenous collagenolytic and gelatinolytic activities in TELF. In vitro inhibition of MMP activity in TELF with 2 chemically modified tetracyclines (CMTs; CMT-3 and CMT-8) and 2 bisphosphonates (BPs; zole...
Antinociceptive effects, metabolism and disposition of ketamine in ponies under target-controlled drug infusion. Ketamine is widely used as an anesthetic in a variety of drug combinations in human and veterinary medicine. Recently, it gained new interest for use in long-term pain therapy administered in sub-anesthetic doses in humans and animals. The purpose of this study was to develop a physiologically based pharmacokinetic (PBPk) model for ketamine in ponies and to investigate the effect of low-dose ketamine infusion on the amplitude and the duration of the nociceptive withdrawal reflex (NWR). A target-controlled infusion (TCI) of ketamine with a target plasma level of 1 microg/ml S-ketamine over 120 ...
Evidence for the expression and enzymatic activity of haem oxygenase-1 in the lungs of horses. The aim of this study was to characterise the expression of haem oxygenase-1 (HO-1) in healthy lung tissue from horses and to measure its activity. Samples of lung tissue were collected from six horses euthanased for reasons other than respiratory disease. HO-1 expression and activity were detected in type II alveolar epithelial cells, macrophages and neutrophils in all the samples examined. The activity was dependent on the presence of NADPH and inhibited quantitatively by the addition of increasing concentrations of a competitive inhibitor of HO-1, tin mesoporphyrin IX.
Effectiveness of acupuncture in veterinary medicine: systematic review. Acupuncture is a popular complementary treatment option in human medicine. Increasingly, owners also seek acupuncture for their animals. The aim of the systematic review reported here was to summarize and assess the clinical evidence for or against the effectiveness of acupuncture in veterinary medicine. Systematic searches were conducted on Medline, Embase, Amed, Cinahl, Japana Centra Revuo Medicina and Chikusan Bunken Kensaku. Hand-searches included conference proceedings, bibliographies, and contact with experts and veterinary acupuncture associations. There were no restrictions regarding t...
Heaves, an asthma-like equine disease, involves airway smooth muscle remodeling. Increased airway smooth muscle mass is a prominent feature of asthmatic airway remodeling. Airway smooth muscle hyperplasia occurs in rodent models of experimental asthma, but the relevance of such finding to spontaneously occurring disease in large mammals is unknown. Objective: We examined horses with heaves, a naturally occurring equine asthma related to sensitization and exposure to moldy hay. We hypothesized that airway remodeling occurs in heaves and shares disease mechanisms with asthma. Methods: We quantified the airway smooth muscle mass and the numbers of proliferating and apoptotic ...
Response to nasopharyngeal oxygen administration in horses with lung disease. Guidelines for administration of oxygen to standing horses are unavailable because previous investigations of the efficacy of oxygen administration to increase arterial oxygenation in standing horses have produced equivocal results. Objective: To determine the effect of nasal oxygen supplementation on inspired and arterial blood gas tensions in control horses and those with moderate to severe recurrent airway obstruction (RAO). Methods: Normal horses (n = 6) and horses during an attack of RAO induced by stabling (n = 6) were studied. Oxygen was administered through either one or 2 cannulae, pa...
Expression of toll-like receptor 4 and 2 in horse lungs. Toll-like receptor (TLR) is a key component in launching innate immune response to microbial challenge. TLR4 and TLR2 are recognized as specific receptors for components of Gram-negative and Gram-positive bacteria, respectively. Horses are extremely sensitive to endotoxin-induced cardiopulmonary distress and mortality which causes significant economic losses. To date, there are no data on the expression of TLR4 and TLR2 in horse lungs. Therefore, we examined the expression of TLR4 and TLR2 in lungs from normal or Escherichia coli lipopolysaccharide (E. coli LPS; 50 ng/kg; iv) treated horses. W...
The anti-inflammatory effects of IV administered clenbuterol in horses with recurrent airway obstruction. Cyclic AMP elevating agents have been shown to exhibit anti-inflammatory properties in addition to functions such as bronchodilation. The aim of this study was to investigate this dual action of clenbuterol (CB; Ventipulmin) on horses affected with recurrent airway obstruction (RAO). Seven RAO susceptible horses received inhalation challenges with aerosolised lipopolysaccharide (LPS), hay dust suspension (HDS) and Aspergillus fumigatus antigen (AF) with and without prior treatment with intravenous CB. Data showed that CB exerted significant beneficial effects on lung function, total cell count...
Surfactant proteins A and D in the genital tract of mares. The presence of surface-active material in the lung alveolus has been known for several decades as being essential for normal lung function. Surfactant is essential for reducing the surface tension at the alveolar air-liquid interface. Pulmonary surfactant is composed of 90% lipids and 10% proteins. There are four non-serum proteins surfactant protein-A (SP-A), surfactant protein-B (SP-B), surfactant protein-C (SP-C) and surfactant protein-D (SP-D) named in chronologic order of discovery. Lung SP-A and SP-D belong to a family of collagen-containing C-type lectin family called collectins. The h...
