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Topic:Respiratory Health
Respiratory health in horses encompasses the study of the equine respiratory system, its function, and the various conditions that can affect it. The respiratory system in horses includes the upper airways, lungs, and associated structures, which facilitate gas exchange and are vital for maintaining physiological homeostasis during rest and exercise. Common respiratory conditions in horses include equine asthma, infectious diseases like strangles, and exercise-induced pulmonary hemorrhage (EIPH). These conditions can impact a horse's performance and overall health. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, pathophysiology, and management of respiratory health in horses.
Endoscope-guided, transoral axial division of an entrapping epiglottic fold in fifteen standing horses. To describe and evaluate the use of a transoral, endoscope-guided technique for transection of an entrapping epiglottic fold in sedated standing horses. Methods: Retrospective study. Methods: Horses (n=16) with epiglottic fold entrapment (EFE). Methods: Medical records (2005-2006) of 16 horses with EFE were reviewed to determine history, physical and endoscopic examination findings, postoperative complications, and outcome after axial division of EFE using a hooked bistoury, under an endoscopic-guided, transoral approach. Results: EFE was confirmed by endoscopy. Axial division was successfully...
Comparison of the effects of caffeine and doxapram on respiratory and cardiovascular function in foals with induced respiratory acidosis. To determine and compare the effects of caffeine and doxapram on cardiorespiratory variables in foals during isoflurane-induced respiratory acidosis. Methods: 6 clinically normal foals (1 to 3 days old). Methods: At intervals of > or = 24 hours, foals received each of 3 IV treatments while in a steady state of hypercapnia induced by isoflurane anesthesia (mean +/- SD, 1.4 +/- 0.3% endtidal isoflurane concentration). After assessment of baseline cardiorespiratory variables, a low dose of the treatment was administered and variables were reassessed; a high dose was then administered, and vari...
Transverse and dorso-ventral changes in thoracic dimension during equine locomotion. Changes in shape of the equine thorax during locomotion are not well defined, although it has been shown recently that the transverse hemi-diameter changes its dimension by up to 80mm on the side of the trailing forelimb during gallop, despite minimal change in thoracic circumference. The aim of this project was to analyse transverse and dorso-ventral changes in shape of the thorax simultaneously, and to determine if leading limb, treadmill slope and speed have an effect on these shape changes. Reflective markers were placed on the horse's hemi-thorax and movement of the markers was recorded u...
Cytochrome P450 3A, NADPH cytochrome P450 reductase and cytochrome b5 in the upper airways in horse. Gene and protein expression as well as catalytic activity of cytochrome P450 (CYP) 3A were studied in the nasal olfactory and respiratory mucosa and the tracheal mucosa of the horse. We also examined the activity of NADPH cytochrome P450 reductase (NADPH P450 reductase), the amount of cytochrome b(5) and the total CYP content in these tissues. Comparative values for the above were obtained using liver as a control. The CYP3A related catalytic activity in the tissues of the upper airways was considerably higher than in the liver. The CYP3A gene and protein expression, on the other hand, was hig...
Performance of the 808-nm diode laser on equine upper airway tissue is enhanced by intravenous administration of indocyanine green. The objective was to develop a protocol whereby 808-nm diode laser irradiation combined with intravenous (IV) indocyanine green (ICG) could be used in non-contact mode with equal surgical efficacy to the Nd:YAG on equine tissues. Background: The 808-nm diode laser, delivering 20-40 W of power, has been produced for veterinary medical applications. This laser's power output is less than that of most neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers. ICG is absorbed at a wavelength of 810 nm, which when concentrated in tissue should be an excellent absorber for the energy produced by the 808-nm ...
Endoscopic removal of a molariform supernumerary intranasal tooth (heterotopic polyodontia) in a horse. A 3-year-old Thoroughbred mare was evaluated because of abnormal upper respiratory tract sounds (that had become apparent during race training) of 3 to 4 months' duration. Results: On initial physical evaluation, there were no abnormal findings. During trotting, an abnormal upper airway expiratory sound was audible. Endoscopic examination revealed a small mass protruding into the right ventral nasal meatus. Radiographic images of the skull revealed no abnormal findings. Computed tomography of the head revealed an abnormal structure in the same location as the mass that was observed during endo...
Calcified tumours of the paranasal sinuses in three horses. Three horses, a 10-year-old Thoroughbred mare, a 9-year-old Thoroughbred gelding and a 6-year-old Arab gelding, with calcified tumours of the paranasal sinuses, are described. All horses presented with purulent nasal discharges and facial distortion. Exophthalmos, blepharospasm and ocular discharge were also a feature in individual horses. A presumptive diagnosis of a calcified tumour was made on the basis of clinical signs and radiographic and endoscopic findings. The tumours ranged from 15 to 25 cm in diameter. A large frontonasal bone flap was used to expose the tumours, which were cleaved ...
Antimicrobial susceptibility of streptococci from various indications of swine, horses, dogs and cats as determined in the BfT-GermVet monitoring program 2004-2006. A total of 500 streptococci from two indications of swine (beta-haemolytic streptococci from infections of the urinary/genital tract including strains from the mastitis metritis agalactia syndrome as well as S. suis from infections of the central nervous system and the musculoskeletal system), two indications of horses (S. equi from respiratory tract infections and beta-haemolytic streptococci from infections of the genital tract), as well as three indications of dogs and cats (beta-haemolytic streptococci from infections of the respiratory tract, the urinary/genital tract, and skin/ear/mouth)...
Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horses. Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. Objective: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. Methods: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. Results...
Comparison of tracheal aspirates before and after high-speed treadmill exercise in racehorses. To determine whether percentages of neutrophils in tracheal aspirate (TA) samples collected from racehorses are increased after exercise and whether interpretation of results from TA samples taken before and after exercise agree. Methods: Case series of 40 young Thoroughbred and Standardbred racehorses in race training presented for evaluation of poor performance. Methods: TA samples were collected endoscopically from racehorses presented for poor performance 24 h before and 1 to 2 h after high speed treadmill exercise testing. Aliquots of the retrieved fluid were cytocentrifuged and smears we...
Adenosine receptor modulation: potential implications in veterinary medicine. Adenosine is a purine nucleoside whose concentration increases during inflammation and hypoxia and the many roles of this molecule are becoming better understood. Increased reactivity to adenosine of the airways of asthmatic but not of normal subjects underlines the role of adenosine in airway inflammation. The identification and pharmacological characterisation of different adenosine receptors have stimulated the search for subtype-specific ligands able to modulate the effects of this molecule in a directed way. Several compounds of different chemical classes have been identified as having po...
Meperidine prolongs lidocaine caudal epidural anaesthesia in the horse. The aim of the study was to evaluate and compare the effects of caudal epidural administration of meperidine (MP), lidocaine (LD), and a combination of the two (MPLD) in six mature saddle horses. Horses were randomly assigned to receive three treatments (MP 0.3 mg/kg; LD 0.2 mg/kg; and MPLD: MP 0.3 mg/kg and LD 0.2 mg/kg), with at least 1 week between treatments. Drugs were injected into the epidural space between the first and second coccygeal areas in conscious standing horses. Analgesia, ataxia, sedation, cardiovascular and respiratory effects, and rectal temperature were recorded at differ...
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...
Persistent dorsal displacement of the soft palate attributable to a frenulum of the epiglottis in a racing Thoroughbred. A 7-year-old sexually intact male Thoroughbred racehorse was evaluated because of exercise intolerance, respiratory tract noise, and coughing when eating. Results: A persistent dorsal displacement of the soft palate was identified during endoscopic examination of the upper portions of the respiratory tract. Radiography of the pharyngeal and laryngeal regions revealed a hypoplastic epiglottis that was ventral to, and not in contact with, the soft palate. The horse was anesthetized, and an oral endoscopic examination revealed a subepiglottic frenulum that had resulted in the dorsal displacement ...
A survey of horse owners in Great Britain regarding horses in their care. Part 2: Risk factors for recurrent airway obstruction. Recurrent airway obstruction (RAO) is a commonly encountered respiratory condition of horses. Despite this, the epidemiology of this predominately manageable and reversible disease in Great Britain has been largely ignored. Objective: To estimate the prevalence of RAO in the general horse population of Great Britain and to investigate possible risk factors for RAO associated with management or early life. Methods: Horse owners were surveyed using a self-administered postal questionnaire that contained a risk-screening questionnaire (RSQ) designed to identify horses with RAO. These owners were ...
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...
A survey of horse owners in Great Britain regarding horses in their care. Part 1: Horse demographic characteristics and management. Information is scarce as to how horses are kept and managed in the general horse population of Great Britain. Objective: To characterise the demographics of horses in Great Britain and assess their care (with particular reference to the respiratory system). Methods: Horse owners were surveyed using a self-administered postal questionnaire. These owners were selected randomly, following geographical stratification, using 2-stage cluster sampling of veterinary practices and their clients. Results: The overall response proportion to the survey was 68.2%. An investigation of nonresponse bias detec...
Physiology of equine performance and associated tests of function. 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...
The cardiopulmonary effects of dobutamine and norepinephrine in isoflurane-anesthetized foals. To evaluate the cardiovascular effects of norepinephrine (NE) and dobutamine (DB) in isoflurane-anesthetized foals. Methods: Prospective laboratory study. Methods: Norepinephrine (0.05, 0.10, 0.20, and 0.40 microg kg(-1) minute(-1)) and dobutamine (2.5, 5.0, and 10 microg kg(-1) minute(-1)) were alternately administered to seven healthy, 1- to 2-week-old isoflurane-anesthetized foals. Arterial and pulmonary arterial blood pressure, right atrial pressure, pulmonary artery occlusion pressure, heart rate, body temperature, cardiac output, arterial and mixed venous blood pH, partial pressure of ca...
Evidence-based equine upper respiratory surgery. The purpose of this article is to review the veterinary literature for various surgical procedures of the equine upper respiratory tract in an effort to evaluate the evidence supporting various therapies. This article focuses on the therapeutic benefit from more widely occurring conditions, such as laryngeal hemiplegia, dorsal displacement of the soft palate, arytenoid chondritis, and epiglottic entrapment.
Evidence-based respiratory medicine in horses. It is clear from a review of the current scientific literature that an evidence-based approach to medical treatment of equine respiratory disease can be applied, at least in the instance of common lower respiratory diseases. In particular, there is clear evidence for efficacious treatments for recurrent airway obstruction and exercise-induced pulmonary hemorrhage, and with the recognition of this evidence, these treatments should be the first to be considered by a practitioner when treating these conditions. The purpose of this article is not only to identify the existence of relevant high-qua...
Relevance of using a human microarray to study gene expression in heaves-affected horses. Environmental causes of heaves are well described, but the molecular mechanisms of the disease remain unclear. Previous studies have highlighted the implications of variations in gene expression, most using reverse transcription polymerase chain reaction (RT-PCR). This well-known technique limits the number of genes that can be studied in a single assay. Microarray appears to be a valuable tool to by-pass this limitation, but so far there has been no equine-specific microarray available on the market. The present study was performed to determine whether a human microarray could be used to stud...
Comparison of ketamine and S(+)-ketamine, with romifidine and diazepam, for total intravenous anesthesia in horses. To compare the quality of induction and recovery, degree of muscle relaxation, clinically apparent potency and cardiopulmonary effects of racemic ketamine or S(+)-ketamine when used for total intravenous anesthesia in horses. Methods: Prospective randomized clinical trial Methods: Sixteen healthy stallions (323 +/- 99 kg), with a mean age of 6.2 years, undergoing castration. Methods: Horses were pre-medicated with romifidine IV, 15 minutes before induction of anesthesia. Each animal was then randomly allocated to receive either diazepam and ketamine (DK) or diazepam and S(+)-ketamine (DKS) at ...
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...
Trimetoquinol: bronchodilator effects in horses with heaves following aerosolised and oral administration. The bronchodilator effects of trimetoquinol (TMQ) have been studied when administered i.v. or intratracheally, but not in an aerosolised form. Objective: To define the relationship between the therapeutic and adverse responses (therapeutic index) of TMQ when administered as an aerosol or by the oral route. Methods: Increasing doses of TMQ were administered to horses with heaves as an aerosol and by the oral route. Dose ranged 100-1000 microg/horse for aerosolised TMQ and from 6-60 microg/kg bwt for the oral route. Airway and cardiac effects were assessed by measurement of maximal change in ple...
A region on equine chromosome 13 is linked to recurrent airway obstruction in horses. REASONS FOR STUDY: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor a chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. Methods: The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood ...
Portable mass spectrometry for measurement of anaesthetic agents and methane in respiratory gases. Monitoring the composition of gases breathed by anaesthetised patients requires measurement methods with fast responses, high accuracy and good reliability. There is also an increasing demand for systems to be able to monitor more than one target analyte simultaneously, but some gas analysers can be sensitive to the presence of methane gas in exhaled breath, consequently leading to inaccurate measurements of the anaesthetic agent. This study investigated the feasibility of employing portable quadrupole mass spectrometry to monitor volatile anaesthetic agents (halothane, isoflurane and sevoflur...
