The trachea, commonly referred to as the windpipe, is a vital component of the equine respiratory system. It functions as a conduit for air passage between the larynx and the bronchi, facilitating respiration in horses. Structurally, the equine trachea is composed of a series of cartilaginous rings that maintain its shape and provide necessary support, preventing collapse during inhalation and exhalation. The inner lining of the trachea is lined with ciliated epithelium and mucus-producing cells, which help trap and expel particulates and pathogens, contributing to respiratory health. This page gathers peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and clinical implications of tracheal health and diseases in horses.
Gregson R, Clutton RE.A 7-year-old gelded Irish sports horse weighing 650 kg was anesthetized on 2 consecutive days for lavage of a septic right radio-carpal joint. On both occasions the endotracheal tube connector, which had been bound in medical tape to produce an airtight seal, functioned as a unidirectional valve during mechanical ventilation, retarding expiration, imposing positive end expiratory pressure (PEEP), and probably continuous positive airway pressure (CPAP). The equipment dysfunction was not identified on either occasion despite close inspection prompted by progressive increases in airway pressure a...
Lester GD, Rice BL.To determine effects of leukotriene (LT) C(4) on ion transport across equine tracheal epithelium. Sample-Tracheal epithelium from cadavers of 24 horses considered free of respiratory tract disease. Methods: Mucosae were mounted into Ussing chambers, and short-circuit current (I(sc)) was monitored over time. Effects of LTC(4) were examined for various conditions, including addition of amiloride (10μM) to the mucosal bath solution, addition of bumetanide (10μM) to the serosal bath solution, addition of barium (1mM) to the serosal bath solution, and substitution of gluconate for chloride and HE...
Tsuchiya T, Hobo S, Endo Y, Narita S, Sakamoto K.To evaluate effects of a single dose of enrofloxacin (5 mg/kg, IV) on body temperature and tracheobronchial neutrophil count in healthy Thoroughbreds premedicated with interferon-α and undergoing long-distance transportation. Methods: 32 healthy Thoroughbreds. Methods: All horses received interferon-α (0.5 U/kg, sublingually, q 24 h) as an immunologic stimulant for 2 days before transportation and on the day of transportation. Horses were randomly assigned to receive enrofloxacin (5 mg/kg, IV, once; enrofloxacin group) or saline (0.9% NaCl) solution (50 mL, IV, once; control group) ≤ 1 hou...
Tee SY, Dart AJ, MacDonald MH, Perkins NR, Horadagoda N, Jeffcott LB.To evaluate the effect of collecting serial tracheal aspirate (TA) and bronchoalveolar lavage (BAL) samples on the cytological findings of subsequent fluid samples obtained from horses without clinical signs of respiratory disease. Methods: Experimental. Methods: Six healthy Standardbred horses. Methods: Endoscopically-guided TA samples, and BAL samples collected using the blind field technique were obtained from the six horses on days 1, 2, 3, 4, 5, 12, and 17. On day 17, horses were sampled three times: at baseline and at 2.5 h and 4 h apart. The differential cytology of the fluid samples co...
Brosnan RJ, Steffey EP, Escobar A.To test the hypothesis that hypercapnic hyperpnea produced using endotracheal insufflation with 5-10% CO(2) in oxygen could be used to shorten anesthetic recovery time in horses, and that recovery from sevoflurane would be faster than from isoflurane. Methods: Randomized crossover study design. Methods: Eight healthy adult horses. Methods: After 2 hours' administration of constant 1.2 times MAC isoflurane or sevoflurane, horses were disconnected from the anesthetic circuit and administered 0, 5, or 10% CO(2) in balance O(2) via endotracheal tube insufflation. End-tidal gas samples were collect...
Millerick-May ML, Karmaus W, Derksen FJ, Berthold B, Holcombe SJ, Robinson NE.Accumulations of tracheal mucus assessed by endoscopic examination are associated with poor performance in racehorses. The air quality in horses' stalls may contribute to this visible tracheal mucus. Objective: To determine whether the concentration and number of airborne particulates in stalls are associated with visible accumulations of tracheal mucus and with the number of inflammatory cells in tracheal aspirates. Methods: We studied 107 racehorses from 3 stables, in 3 different months, and measured airborne particulate matter 3 times daily in each of the stalls. On each monthly visit, hors...
Crumley MN, Hodgson DS, Kreider SE.To measure the effects of tidal volume, ventilatory frequency, and oxygen insufflation flow on the fraction of inspired oxygen in cadaveric horse heads attached to a lung model. Methods: 8 heads of equine cadavers. Methods: Each cadaveric horse head was intubated with a nasotracheal tube that extended into the proximal portion of the trachea. Oxygen was delivered through an oxygen catheter contained within and extending to the tip of the nasotracheal tube. The trachea was connected to the lung model by use of a spiral-wound hose with a sampling adaptor. Eight treatment combinations involving 2...
Koblinger K, Nicol J, McDonald K, Wasko A, Logie N, Weiss M, Léguillette R.Comprehensive endoscopic scoring of the upper and lower airways for inflammation has not been critically assessed among a large population of horses. The relationship between upper and lower airways described in humans by the "one airway, one disease" concept might also apply to horses. Objective: To evaluate if an association exists between endoscopic inflammatory scores and mucus scores of upper and lower airways and to investigate if endoscopic findings correlate with the lower airway inflammation measured by bronchoalveolar lavage (BAL) cytology. Methods: Prospective field study. Pharyngit...
Alworth LC, Hart KA, Kelly LM, Harvey SB.Transtracheal access enables researchers to obtain diagnostic samples from or infuse materials into the lower respiratory tract. This column describes transtracheal aspiration and infusion of horses.
Fjordbakk CT, Holcombe S, Fintl C, Chalmers H, Strand E.Dynamic laryngeal collapse (DLC) associated with poll flexion is a performance limiting dynamic upper airway disorder commonly diagnosed in Coldblooded trotters. An inspiratory obstruction occurs when affected horses are driven with tension on the reins, inducing poll flexion. To date, surgical treatment and conservative management have failed to improve racing performance in affected horses. Objective: To test the efficacy of an external device, the modified checkrein, in limiting poll flexion, diminishing laryngeal collapse and improving airway mechanics when horses are driven on a treadmill...
Cardwell JM, Christley RM, Gerber V, Malikides N, Wood JL, Newton JR, Hodgson JL.The term 'inflammatory airway disease' (IAD) is often used to describe the syndrome of lower airway inflammation that frequently affects young racehorses in training around the world. In practice, this inflammation is generally diagnosed using a combination of endoscopic tracheal examination, including grading of amounts of mucus present and tracheal wash sampling. However, a recent consensus statement from the American College of Veterinary Internal Medicine concluded that bronchoalveolar lavage (BAL) sampling, rather than tracheal wash (TW) sampling, is required for cytological diagnosis of ...
Cardwell JM, Wood JL, Smith KC, Newton JR.Rates of airway inflammation in young racehorses decrease with time but it is not clear whether this is associated with increasing age or time exposed to the training environment. The structure of the British National Hunt (NH) population allowed closer examination of this relationship. Objective: To compare rates of inflammatory airway disease diagnosed by tracheal sampling (trIAD), and its components, in NH racehorses by age and training history and with published rates in young racehorses. Methods: A prospective, longitudinal study was conducted on 5 NH yards over 2 years. Period sample pre...
Millerick-May ML, Karmaus W, Derksen FJ, Berthold B, Holcombe SJ, Robinson NE.Airway inflammation and mucus in the trachea are common in racehorses. Fine airborne particles can initiate and coarse particles can worsen airway inflammation in man and in animal models of airway disease. The regional and seasonal distribution of particles of different sizes has never been investigated in American racing stables. Objective: To determine the regional and seasonal concentration and number of airborne particles of different sizes in racing stables. Methods: Direct reading instruments were used to determine the mass concentration and numbers of particles 3 times daily (early mor...
Goncarovs KO, Miskovic Feutz M, Perez-Moreno C, Couetil LL.One proposed nonmedical therapy for recurrent airway obstruction (RAO) in horses is a handheld acoustic device that propels sound waves from the nose down the tracheobronchial tree where it is intended to dislodge mucous and relax bronchospasm, permitting clearance of mucoid secretions. Objective: To evaluate the effectiveness and safety of this device when used as per the manufacturer's recommendations as a treatment for RAO. Methods: Nine adult horses previously diagnosed with RAO. Methods: Prospective, cross-over clinical trial. Horses were exposed to a dusty environment until airway obstru...
Pigott JH, Ducharme NG, Mitchell LM, Soderholm LV, Cheetham J.The relationship between dorsal displacement of the soft palate (DDSP) and swallowing is unclear. Objective: To quantify the relationship between DDSP and swallowing in horses at exercise. Objective: The frequency of swallowing increases immediately prior to DDSP in horses at exercise. Methods: Videoendoscopic and upper airway pressure data were collated from horses with a definitive diagnosis of DDSP at exercise. Horses with no upper airway abnormalities were matched by age, breed and sex and used as controls. Sixty-nine horses were identified with a definitive diagnosis of DDSP during the st...
Garrett KS, Woodie JB, Cook JL, Williams NM.A foal was examined for abnormal upper airway noise. Endoscopically, there were narrowed nasal passages and an extralumenal mass of the cranial trachea. Using ultrasonography and magnetic resonance (MR) imaging of the larynx and cranial cervical trachea, irregular margins of the laryngeal cartilages and first tracheal ring containing areas consistent with fluid were identified. In MR images, a widened nasal septum was seen that contained material consistent with fluid. Postmortem examination confirmed the diagnosis of nasal septal, laryngeal, and cranial cervical tracheal cyst-like lesions. Th...
Muranaka M, Yamanaka T, Katayama Y, Hidari K, Kanazawa H, Suzuki T, Oku K, Oyamada T.It is strongly suspected that equine influenza virus (EIV) is the origin of canine influenza virus (CIV, H3N8), which was first isolated in U.S.A. in 2004, on the basis of phylogenetic analyses. Although the distribution of influenza virus sialoreceptors seems to be associated with this interspecies transmission, there have been scant data of comparison about distributions of sialoreceptors on the whole respiratory tract between horses and dogs. We examined the histological distribution of influenza virus sialoreceptors on the upper and lower respiratory tract in detail in both animals using d...
Busschers E, Epstein KL, Holt DE, Parente EJ.To describe the surgical technique, complications, and outcome after use of extraluminal prostheses in 2 ponies with severe tracheal collapse. Methods: Clinical report. Methods: Ponies (n=2) with severe tracheal collapse. Methods: A ventral median approach was used to expose the trachea from the larynx to the manubrium. Extraluminal, high-density polyethylene, C-shaped prostheses were sutured to the dorsal tracheal membrane and tracheal rings to provide external tracheal support. Results: The surgical approach provided good tracheal access and placement of the rings was uncomplicated. Initial ...
Evans DL, Kiddell L, Smith CL.Inflammatory airway disease (IAD) is common in racehorses, and is a cause of wastage in the industry. IAD has been diagnosed by measurement of percent neutrophils (N%) in tracheal aspirates (TA). The aim of this study was to investigate whether spirometric indices of pulmonary function were correlated with N% in TAs. Limits to breathing were measured by analyses of relationships between relative times and relative respiratory gas flows during inspiration and expiration in individual breaths recorded after exercise. Horses with higher N% had significantly lower relative gas flows at the same re...
Oslund KL, Adamson G, Wu R.To isolate and culture primary equine airway epithelial cells in vitro and elucidate the major cytokines involved in expression of the gel-forming mucin gene MUC5AC in horses. Methods: 12 tracheas obtained within 5 hours after euthanasia from horses free from respiratory tract disease. Methods: Tracheal rings were digested overnight in 0.2% protease, and dissociated airway epithelial cells were grown in a serum-free defined medium at an air-liquid interface until confluence was achieved. Differentiated airway epithelial cells were treated with a panel of recombinant equine cytokines followed b...
Kaartinen MJ, Pang DS, Cuvelliez SG.CASE 1: A two-year old, 462 kg Standard bred horse was anesthetized for arthroscopy and castration. During anesthesia, hyperemia of the mucosal membranes and urticaria were noticed. During 5 hours of anesthesia subcutaneous edema of the eyelids and neck region developed. In the recovery box, the orotracheal (OT) tube was left in situ and secured in place with tape. Following initial attempts to stand, the horse became highly agitated and signs consistent with pulmonary edema developed subsequently. Arterial hypoxemia (PaO(2): 3.7 kPa [28 mmHg]) and hypocapnia (PaCO(2): 3.1 kPa [23 mmHg]) were ...
Powell RJ, du Toit N, Burden FA, Dixon PM.There is limited information on the gross tracheal morphology of donkeys with or without tracheal abnormalities. Objective: To: 1) examine the morphology of tracheas of donkeys with and without clinical and/or post mortem evidence of tracheal obstruction; 2) record the cross-sectional dimensions and shapes of tracheal rings at fixed sites; and 3) document prevalence, sites and characteristics of detected tracheal abnormalities. Methods: The tracheas of 75, predominantly aged (median age 30 years, range 7-48 years) donkeys that died or were subjected to euthanasia on humane grounds were examine...
Matsuda K, Qiu Y, Furuse T, Kawamura Y, Yokoyama D, Kato A, Taniyama H.This report documents an unusual case of congenital foregut cyst with dysphagia and stridor in a Thoroughbred foal. Histologically, the bilocular cyst, near the junction of larynx and trachea, had an epithelial lining of bronchogenic and esophageal origin. Concomitant malformation of the laryngeal muscles and cartilage resulted in a combination of anomalies that have not been reported in the human or veterinary literature.
Leclere M, Magdesian KG, Kass PH, Pusterla N, Rhodes DM.The purpose of this study was to compare the clinical, microbiological, radiological, haematological and cytological features of foals with pneumonia caused by Rhodococcus equi infection and with other bacteria, in order to provide markers for early diagnosis and treatment. A retrospective study of 113 cases of bacterial pneumonia was undertaken. Although there was considerable overlap in the affected populations, foals with R. equi pneumonia were significantly younger and had higher respiratory rates. Radiological evidence of thoracic abscessation had a sensitivity of 71% and a specificity of...
Saulez MN, Gummow B.Endoscopic examinations were performed on 1005 thoroughbred racehorses in South Africa a mean (sd) 24 (12.3) minutes after racing, to determine the prevalence of pharyngeal, laryngeal and tracheal disorders, and to determine the relationship of these disorders with performance (number of wins and placed finishes). Overall, there was a low prevalence of grade 2 and 3 laryngeal function (LF) (2.2 per cent), grade 4 LF (0.6 per cent), epiglottic entrapment (1.3 per cent), subepiglottic cyst (0.2 per cent) and epiglottic deformity (0.6 per cent), while a higher prevalence of grade 2 to 4 pharyngea...
Carstens A, Kirberger RM, Grimbeek RJ, Donnellan CM, Saulez MN.Radiographic measurement of tracheal dimensions in the horse may be useful in evaluating upper and lower respiratory tract conditions due to the gradient of pressure changes between these areas. Lateral radiographs of the trachea of 15 normal sedated Thoroughbred horses were made at inspiration and expiration and magnification-corrected mean airway heights measured were, respectively: larynx: 5.89 and 5.86 cm; trachea at the third cervical vertebra (C3): 4.17 and 4.04cm; at the fifth cervical vertebra (C5): 3.62 and 3.59 cm; at the first thoracic vertebra (T1): 3.4 and 3.23cm; and carina: 3.85...
Winther L, Andersen RM, Baptiste KE, Aalbæk B, Guardabassi L.Stenotrophomonas maltophilia is being reported with increasing frequency as a human nosocomial pathogen, especially among immuno-compromised patients. To the authors' knowledge, this pathogen has not previously been associated with lower airway disease in the horse. In this paper the clinical findings, laboratory diagnosis and response to treatment of seven cases of respiratory infection with S. maltophilia in horses, presented at three equine referral hospitals in Denmark in 2007, are described. In all cases there was a clinical history of chronic coughing and abundant mucopurulent exudate wa...
Saulez MN, Dzikiti B, Voigt A.Two of 348 horses that underwent gastrointestinal surgery under general anaesthesia developed perforations in their tracheas caused by the endotracheal tube. In one case the damage was probably caused when the horse was being moved from the induction room for surgery and excessive traction was exerted on the tube when the anaesthetic machine was moved too far ahead of the horse. The trachea of the other horse may have been damaged when it was intubated.
Fortier G, van Erck E, Fortier C, Richard E, Pottier D, Pronost S, Miszczak F, Thiry E, Lekeux P.The objectives of this study were to estimate the prevalence and the potential role of equine herpesviruses (EHVs) detection in both bronchoalveolar lavage (BAL) and tracheal wash (TW). The population included a control group (CTL; 37 TW and 25 BAL) and a pathological group (PAT; 259 TW and 387 BAL), including horses either suffering from respiratory diseases including syndrome of tracheal inflammation, inflammatory airway disease, recurrent airway obstruction, or submitted to respiratory investigation because of exercise intolerance or poor performance. Each respiratory liquid was submitted t...
Strand E, Fjordbakk CT, Holcombe SJ, Risberg A, Chalmers HJ.Dynamic laryngeal collapse (DLC) associated with poll flexion is a newly diagnosed upper respiratory tract obstructive disorder that causes poor racing performance. Objective: To determine if Norwegian Coldblooded Trotters (NCTs) affected with DLC associated with poll flexion differ from normal, elite NCTs based on simple airway mechanics measurements. Methods: Five normal elite NCTs and 6 NCTs diagnosed previously with DLC underwent treadmill videoendoscopy while tracheal pressures were measured continuously. Alternating head positions were used such that horses were exercised with free head ...
Sullivan SL, Whittem T, Morley PS, Hinchcliff KW.Furosemide is the most commonly used medication for exercise-induced pulmonary haemorrhage (EIPH); however, critical evaluation of the strength of evidence for efficacy of furosemide is lacking and is warranted so that evidence-based treatment decisions can be made. Objective: To evaluate the efficacy of furosemide to reduce the severity or frequency of detection of EIPH in Thoroughbred and Standardbred racehorses. Methods: Systematic review with meta-analyses. Methods: Primary studies were identified via searches of electronic databases, relevant texts and reference lists of published article...
Harrington JR, Golding MC, Martens RJ, Halbert ND, Cohen ND.To evaluate a real-time quantitative polymerase chain reaction (QPCR) assay in the detection and quantitation of virulent Rhodococcus equi. Methods: 1 virulent, 2 intermediately virulent, and 2 avirulent strains of R. equi and 16 isolates of bacteria genetically related to R. equi. Methods: The QPCR assay was evaluated for detection and quantitation of the virulence-associated gene (vapA) of R. equi in pure culture and in samples of tracheobronchial fluid, which were inoculated with known numbers of virulent R. equi. Results were compared with those derived via quantitative microbial culture a...
Heath RB, Steffey EP, Thurmon JC, Wertz EM, Meagher DM, Hyyppa T, Van Slyke GL.Sequelae of routine orotracheal intubation under clinical conditions were characterised in 38 healthy horses presented at three veterinary medical teaching hospitals. Four of these were necropsied and their tissues studied histologically. To minimise variation, 30 mm id cuffed silicone endotracheal tubes or Cole cuffless tubes were used in all patients. Fibreoptic endoscopic examination of upper respiratory and tracheal areas was accomplished pre-intubation, immediately post extubation and after 24 h. Endoscopy revealed that intubation was associated with laryngeal and/or tracheal lesions in a...
Robinson NE, Sorenson PR.Obstruction of the upper and lower airways is common in horses. In the upper airway, paresis of abductor muscles of the nares and larynx allows inspiratory collapse of soft tissues, which is accentuated by factors increasing upper airway resistance and by high inspiratory flow rates. Intrapulmonary airway obstruction occurs due to accumulation of secretions, release of chemical mediators in response to a variety of stimuli, and parasympathetic stimulation of airways. Obstruction of large airways increases the work of breathing, whereas obstruction of small airways may cause no measurable incre...
Ducharme NG, Hackett RP, Ainsworth DM, Erb HN, Shannon KJ.Repeatability of measurements of peak and mean tracheal and pharyngeal pressures in exercising horses was determined. Five athletically fit horses were subjected to repeated (n = 5) standardized exercise trials. Static pressures in the trachea, nasopharynx, and mask were determined. At least 96% of all mean pressure measurements were within 5 cm of H2O of the mean value for any horse. Peak pressure measurements were less repeatable, but at least 96% of all measurements were within 10 cm of H2O of the mean peak measurements for any horse. In 10 horses galloping at 14 m/s, the 95% confidence int...
Allano M, Labrecque O, Rodriguez Batista E, Beauchamp G, Bédard C, Lavoie JP, Leclere M.The aim of this study was to determine the effects of short distance transportation on airway mucus, cytology and bacterial culture to identify potential biases in the diagnosis of airway diseases in referral centres. Eight healthy adult horses were studied using a prospective cross-over design. Mucus scores, tracheal wash (cytology, bacterial culture) and bronchoalveolar lavage fluid (BALF; cytology) were obtained while stabled and following 2.5 h transportation (with and without hay). Neutrophil counts, percentages and BALF neutrophilia frequency increased following transport without hay (...
van Nieuwstadt RA, Henricks PA, Hajer R, van der Meer van Roomen WA, Breukink HJ, Nijkamp FP.This study was undertaken to assess the importance of muscarinic receptor subtypes in equine airway disease. Smooth muscle strips from the mid-cervical portion of the trachea of horses were placed in tissue baths and isometric contractile force was measured. Active force was measured in response to metacholine and the selective muscarinic receptor agonists McN-A-343 (M1-selective) and pilocarpine (M2-selective) in cumulative concentrations (10(-9)M through 10(-3)M), with and without preincubation with three or four concentrations of the selective muscarinic receptor antagonists pirenzepine (M1...
Broadstone RV, LeBlanc PH, Derksen FJ, Robinson NE.The in vitro contractile and relaxant responses of tracheal smooth muscle strips (TSM) and third-generation bronchi (3B) of control horses and horses with recurrent obstructive disease (heaves) were compared. Acetylcholine (ACH) sensitivity of the diseased tissues was less than that of tissues from control horses, especially at the level of the third generation (EC50 controls 15 +/- 11 microM vs 81 +/- 17 microM for heaveys). Despite tracheal and bronchial hyporesponsiveness to ACH, these tissues from heavey horses were hyperresponsive to EFS. The inhibitory effect of isoproterenol and electri...
Saulez MN, Gummow B.Endoscopic examinations were performed on 1005 thoroughbred racehorses in South Africa a mean (sd) 24 (12.3) minutes after racing, to determine the prevalence of pharyngeal, laryngeal and tracheal disorders, and to determine the relationship of these disorders with performance (number of wins and placed finishes). Overall, there was a low prevalence of grade 2 and 3 laryngeal function (LF) (2.2 per cent), grade 4 LF (0.6 per cent), epiglottic entrapment (1.3 per cent), subepiglottic cyst (0.2 per cent) and epiglottic deformity (0.6 per cent), while a higher prevalence of grade 2 to 4 pharyngea...
Koivunen AL, Maisi P, Konttinen YT, Prikk K, Sandholm M.The collagenolytic activity and its sensitivity to doxycycline inhibition in tracheal aspirates (TA) of horses with chronic obstructive pulmonary disease (COPD) was analyzed with SDS-PA gel electrophoresis (SDS-PAGE), using Type 1 collagen as the substrate. Both autoactive and total collagenase activities were significantly higher in TAs of horses with symptomatic COPD than in TAs of healthy horses. Doxycycline inhibition studies suggest that most of the TA collagenase is of the neutrophil type (MMP-8), but some is derived from other cells such as fibroblasts and monocyte/macrophages (MMP-1) a...
Hobo S, Yoshida K, Yoshihara T.Equine respiratory patterns during swimming were examined in five normal horses. The experiment included a preliminary warming-up stage and 6 circuits of swimming around an annular pool of a 50-meter-circumference. The horses were examined for respiratory rates, intratracheal pressures, inspiratory time (TI), expiratory time (TE), respiratory cycle (T; TI + TE), heart rates, blood lactate concentrations, hematocrit and blood gases. The respiratory rates were maintained around 25/min. Blood gas values changed significantly during swimming. The intratracheal pressures during expiration and inspi...
Holcombe SJ, Derksen FJ, Stick JA, Robinson NE.Dorsal displacement of the soft palate (DDSP) is an intermittent obstructive upper airway condition that occurs in athletic horses during high-intensity exercise. The pathogenesis of this condition is unknown, but may involve epiglottic hypoplasia, malformation, or neuromuscular dysfunction. In this paper, we report on investigations into the pathophysiology of DDSP. In 3 separate experiments, Standardbred horses were exercised on a high-speed treadmill at speeds corresponding to 50, 75 and 100% of maximum heart rate. The upper airway was evaluated by videoendoscopy and measurement of tracheal...
Gerber V, Gehr P, Straub R, Frenz M, King M, Im Hof V.The aim of this ex-vivo study on excised tracheas of healthy horses was to characterise the microscopic heterogeneity of mucus quality by a visual grading system based on transparency and to determine whether differences in mucus quality, assessed by a visual grading system, influence tracheal mucus velocity (TMV). Small pieces of each trachea were mounted into a humidified chamber under a microscope. Mucus quality was visually subdivided into four grades (MG) and ciliary beat frequency and TMV were determined. Mucus on excised horse tracheal epithelium does not form a homogenous layer. We obs...
Durando MM, Martin BB, Hammer EJ, Langsam SP, Birks EK.The primary goal was to investigate the relationship between dynamic upper airway abnormalities and arterial blood gas tensions during exercise. Horses that completed a high-speed treadmill examination consisting of upper-airway videoendoscopy, blood gas evaluation and electrocardiogams and, postexercise, echocardiograms and tracheal washes, were included. An age-matched group of fit, healthy Thoroughbreds, trained to run on a high-speed treadmill, served as controls for blood gas values at specific exercise speeds. One hundred and nineteen horses completed the treadmill examination. Sixty (50...
Seahorn TL, Beadle RE, McGorum BC, Marley CL.To determine whether horses with summer pasture-associated obstructive pulmonary disease (SPAOPD) have increased concentrations of antigen-specific IgG and IgE in tracheal lavage fluid, compared with values in clinically normal horses. Methods: 8 horses (6 females, 2 geldings; 6 Quarter Horses, 2 Appaloosas), 14 to 23 years old and with previous diagnosis of SPAOPD, served as the principal group; 8 horses (2 females, 6 geldings; 1 Quarter Horse, 7 Thoroughbreds), 6 to 9 years old, with no evidence of respiratory tract disease, served as the control group. Methods: Data were collected twice dur...
Nielan GJ, Rehder RS, Ducharme NG, Hackett RP.A nasotracheal catheter for measuring tracheal static pressure in exercising horses was designed according to aerodynamic engineering principles. Small ports near the end of the catheter transmitted pressure fluctuations to the recording apparatus. Accuracy was determined by the size, number, and location of pressure sensing holes on the catheter, and by the position of the catheter in the trachea. The catheter had adequate frequency response to 33 Hz, was insensitive to movement artifacts, was easily introduced, was tolerated well by horses, and resulted in small ventilatory impairment at max...
Wysocka B, Kluciński W.The aim of the present study was to use endoscopic evaluation to compare the grade of accumulation of discharge in the lower airways of horses with recurrent airway obstruction (RAO) and inflammatory airway disease (IAD), and to estimate the usefulness of endoscopic evaluation in differential diagnosis of these diseases. Endoscopic evaluation consists of: the amount of discharge in the lower part of the trachea and tracheal bifurcation, and the assessment of tracheal septum thickness. This study was performed on 248 horses, 10 were healthy, 97 were diagnosed as RAO, and 141 were diagnosed as I...
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) ...
Racklyeft DJ, Love DN.Twenty four normal, confined mares were unable to lower their heads for 24 or 48 h. In 21 mares this resulted in increases in the proportion of neutrophils and/or numbers of bacteria in transtracheal aspirates. In eight mares the changes in tracheal washes were accompanied by clinical evidence of mild respiratory disease. In three additional cases respiratory signs were accompanied by systemic illness. These changes reversed once the mares were able to lower their heads. Haematological changes (absolute neutrophilia and/or hyperfibrinogenamia) were mild and occurred more commonly in horses res...
Clarke DL.Chondromalacia of the tracheal and bronchial cartilages and redundancy of the dorsal tracheal membrane result in collapse of the large airways, leading to coughing and airway obstruction. It most commonly affects small-breed dogs, although larger-breed dogs, cats, and miniature horses are also sporadically reported. Dynamic airway imaging is used to confirm the diagnosis. The primary goal of medical management is to control clinical signs attributable to coughing and airway inflammation. When this is no longer effective, tracheal stents provide a minimally invasive, rapid way to restore airway...
Widdicombe JH, Pecson IS.Horses commonly suffer from respiratory diseases associated with excess secretions in the airway lumen, some of which are presumably derived from airway mucous glands. However, these structures have been little investigated in the horse. Accordingly, we describe here the number, distribution and size of equine tracheal mucous glands, and compare the data with similar information for other mammalian species. Two types of gland acini were present. In the thick connective tissue, up to 400 microm beneath the epithelium, gland acini were grouped in thin sheets that, in cross-section, averaged 20 m...
Zhang XY, Zhu FX, Olszewski MA, Robinson NE.The beta 2-agonists currently used as bronchodilators are racemic mixtures of R- and S-enantiomers. In the present study, we examined the effects of enantiomers of the beta 2-agonists albuterol and formoterol on acetylcholine (ACh) release from equine trachealis parasympathetic nerves. ACh release was evoked by electrical field stimulation (20 V, 0.5 ms, 0.5 Hz) and measured by high-performance liquid chromatography coupled with electrochemical detection. We also tested the effects of enantiomers of albuterol and formoterol on equine tracheal smooth muscle (TSM) contraction in response to exog...
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...
Tsuchiya T, Hobo S, Endo Y, Narita S, Sakamoto K.To evaluate effects of a single dose of enrofloxacin (5 mg/kg, IV) on body temperature and tracheobronchial neutrophil count in healthy Thoroughbreds premedicated with interferon-α and undergoing long-distance transportation. Methods: 32 healthy Thoroughbreds. Methods: All horses received interferon-α (0.5 U/kg, sublingually, q 24 h) as an immunologic stimulant for 2 days before transportation and on the day of transportation. Horses were randomly assigned to receive enrofloxacin (5 mg/kg, IV, once; enrofloxacin group) or saline (0.9% NaCl) solution (50 mL, IV, once; control group) ≤ 1 hou...
Salz RO, Ahern BJ, Boston R, Begg LM.To determine the variation of tracheal mucus scores, tracheal blood scores and transendoscopic tracheal wash (TW) cytology in a population of Thoroughbred (TB) racehorses and assess their association with racing performance. Methods: A total of 220 endoscopic examinations were performed and TWs obtained from 155 TB racehorses. Samples were collected 60-120 min following gallop work. Tracheal mucus score, tracheal blood score and TW cytology were analysed and their association with racing performance assessed. Results: Of the total examinations and samples, 194 from 135 horses fitted the criter...
Leclere M, Magdesian KG, Kass PH, Pusterla N, Rhodes DM.The purpose of this study was to compare the clinical, microbiological, radiological, haematological and cytological features of foals with pneumonia caused by Rhodococcus equi infection and with other bacteria, in order to provide markers for early diagnosis and treatment. A retrospective study of 113 cases of bacterial pneumonia was undertaken. Although there was considerable overlap in the affected populations, foals with R. equi pneumonia were significantly younger and had higher respiratory rates. Radiological evidence of thoracic abscessation had a sensitivity of 71% and a specificity of...
Mair TS, Batten EH, Stokes CR, Bourne FJ.Mucosal lymphoid nodules were identified within the equine respiratory tract by an acetic acid fixation technique. Nodules were identified in foetuses from nine months gestational age, and estimates of total and regional nodule populations were made in foetal, neonatal and adult horses. Nodules occurred at specific sites within the tract, which probably relate to areas where inhaled antigens accumulate. The largest populations of nodules occurred in the nasopharynx and larynx, with smaller numbers in the nasal cavity, trachea and bronchi. There was an age-related change in the size of these no...
