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.
Im Hof V, Gehr P, Gerber V, Lee MM, Schürch S.We measured the surface tension in the trachea of the non-anaesthetised horse from the spreading behaviour of fluid drops, using videotracheoscopy. To do this, we placed small oil drops onto the tracheal wall with a thin Teflon tubing inserted into a videocolonoscope used in humans. Either 5 ml of saline (control) or 5 ml of bovine lipid extract surfactant (BLES) at 4 mg/ml were administered. Tracheal surface tension was 31.9 +/- 0.54 mN/m (Mean +/- SEM, n = 30) in the control experiments and 24.5 +/- 0.51 mN/m (Mean +/- SEM, n = 21) in the entire trachea after the administration of BLES. Thes...
Anzai T, Wada R, Nakanishi A, Kamada M, Takai S, Shindo Y, Tsubaki S.The diagnostic value of tracheal aspiration was evaluated through comparison with other diagnostic methods using an experimental model of Rhodococcus equi (R. equi) pneumonia in foals. Pneumonia was induced by spraying of the virulent R. equi strain ATCC 33701 into the trachea of foals. All foals developed fever from 11 to 16 days after bacterial inoculation. One foal was euthanized on day 26 due to its poor prognosis, and other foals euthanized on day 43. During the experiment, some tests for diagnosis of Rhodococcus equi pneumonia such as tracheal aspiration, radiography, serodiagnosis and f...
Wada R, Kamada M, Anzai T, Nakanishi A, Kanemaru T, Takai S, Tsubaki S.Twelve foals, between 27 and 83 days old, were infected with 2 strains of Rhodococcus equi by intratracheal administration. Ten of the 12 foals were inoculated with 10(4)-10(10) colony forming units (cfu) of ATCC 33701 strain. The other 2 foals were inoculated with 10(9) cfu of a plasmid-cured derivative of the ATCC 33701 strain (ATCC 33701P-). All of the 10 foals challenged with the ATCC 33701 strain showed clinical signs of pulmonary disease within 5-13 days, such as gross lesions associated with acute bronchopneumonia and microscopic lesions associated with granulomatous pneumonia. The two ...
Törneke K, Larsson CI, Appelgren LE.Strips of tracheal smooth muscle from 12 horses were contracted by carbachol in tissue baths under isometric conditions. This contraction (approximately 50% of maximum: EC50) was relaxed completely with adrenoceptor drugs. The only exception was clenbuterol, where the degree of relaxation was approximately 90%. In all horses the EC50-value for isoprenaline (mean 1.6 x 10(-8) M) was less than that for adrenaline (mean 9.6 x 10(-8) M) and noradrenaline (mean 1.8 x 10(-6) M). The potency ratio was 1 < 6 < 110 which indicates that the beta 2-subtype dominates among the beta-adrenoceptors of ...
Tomasic M, Mann LS, Soma LR.To determine the effects of endotracheal intubation on respiratory mechanics during xylazine sedation and xylazine-diazepam-ketamine anesthesia in adult horses. Methods: 5 healthy adult horses. Methods: Measurements were derived from recordings of respiratory gas flow, and transpulmonary and transtracheal pressures. Total pulmonary resistance (RT) was partitioned into upper airway resistance (extrathoracic portion of trachea, larynx, pharynx, nasal cavity, nares; RUA) and lower airway resistance (intrathoracic portion of trachea, bronchi, bronchioles). Baseline measurements were obtained in un...
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...
Bayly WM, Slocombe RF.Effects of respiratory tract obstructions on ventilatory mechanics in horses exercising at high speeds were tested with a fibreglass replica of the airways (nares to mainstem bronchi) of an adult horse. Segmental pressures were recorded at six sites along the model at four different unidirectional flows (1300-4100 litre min-1), and the respective resistances (R) to airflow were calculated. The external nares and the larynx made the greatest contributions to the total resistance (RTOT) when no obstruction was present. Modifying the model to simulate severe pharyngeal lymphoid hyperplasia (PLH) ...
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...
Sime A, McKellar Q, Nolan A.A serum-free cell culture method was developed for equine tracheal epithelial cells which allowed the growth and characterisation of the phenotypical properties of this cell type. Several variables influenced the efficacy of the attachment and growth of the isolated cells. Serum and a collagen matrix were essential components for efficient cell attachment. Once attachment had occurred, cell growth was enhanced by a serum-free medium containing bovine pituitary extract, retinoic acid, insulin, hydrocortisone, transferrin, epidermal growth factor, adrenaline and triiodothyronine. The mean time t...
Koivunen AL, Maisi P, Konttinen YT, Sandholm M.The gelatinolytic activity in tracheal aspirates (TA) of horses with chronic obstructive pulmonary disease (COPD) was analyzed using SDS-PAGE-gelatin-gel electrophoresis (zymography) and compared to TAs from healthy controls. The 110-90 kD MMP-9 type gelatinase was high in symptomatic disease phases (permanent disease 0.46 +/- 0.15, p < 0.001; or intermittent disease 0.47 +/- 0.12, p < 0.001) compared to healthy controls (0.10 +/- 0.07). Similarly, the overall gelatinolytic activity, the activity in high-mw gelatinolytic bands (210-190 and 150 kD) and in proteolytically processed fragments in ...
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...
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...
Zhang XY, Zhu FX, Robinson NE.We examined the effect of activation of beta 2-adrenoceptor (AR) by isoproterenol (ISO) on acetylcholine (ACh) release evoked by electrical field stimulation (EFS: 20 V, 0.5 Hz, 0.5 msec) from cholinergic nerves in five regions of equine airways. We also tested if the effect of ISO was dependent on epithelium or prostanoids by examining the effect of ISO on ACh release in the presence and absence of epithelium or cyclooxygenase inhibition. Trachealis strips or bronchial rings were preincubated for 60 min with 10(-7) M atropine, 10(-6) M neostigmine, and 10(-5) M guanethidine. The ACh amount wa...
Holcombe SJ, Derksen FJ, Stick JA, Robinson NE, Boehler DA.To compare tracheal and pharyngeal inspiratory and expiratory pressures achieved during 60 seconds of nasal occlusion in standing horses with pressures achieved in horses during intense exercise. Methods: 5 Standardbreds. Methods: Tracheal and pharyngeal inspiratory and expiratory pressures were obtained from 5 horses during 60 seconds of nasal occlusion and compared with tracheal and pharyngeal pressures achieved during incremental treadmill exercise tests in which horses ran at 50, 75, and 100% of the speed that resulted in maximal heart rate (HRmax). Results: Significant difference was not ...
Yu MF, Ewaskiewicz JI, Adda S, Bailey K, Harris V, Sosnoski D, Tomasic M, Wilson J, Kotlikoff MI.We report adenovirus-mediated gene transfer into airway smooth muscle cells in cultured cells and organ-cultured tracheal segments. Incubation of cultured rat tracheal myocytes with virus (5 x 10(8) pfu/ml) for 6 h resulted in beta-galactosidase expression in 94.8 +/- 2.5% of cells (n = 4). Following incubation of thin (less than 200 microns diameter) equine trachealis muscle segments with virus in organ culture (5 x 10(8)-5 x 10(10) pfu/ml) the average expression of the Lac Z gene was approximately 19 +/- 10% (n = 9). Expression was markedly improved, however, in segments from neonatal rats (...
The Journal of physiologyApril 15, 1996
Volume 492 ( Pt 2), Issue Pt 2 347-358 doi: 10.1113/jphysiol.1996.sp021313
Fleischmann BK, Wang YX, Pring M, Kotlikoff MI.1. The relationship between voltage-dependent calcium channel current (I(Ca)) and cytosolic free calcium concentration ([Ca2+]i) was studied in fura-2 AM-loaded equine tracheal myocytes at 35 degrees C and 1.8 mM Ca2+ using the nystatin patch clamp method. The average cytosolic calcium buffering constant was 77 +/- 3 (n = 14), and the endogenous calcium buffering constant component is likely to be between 15 and 50. 2. I(Ca) did not evoke significant calcium-induced calcium release (CICR) since (i)[Ca2+]i scaled with the integrated I(Ca) over the full voltage range of evoked calcium currents, ...
Zhang XY, Robinson NE, Zhu FX.We tested the hypothesis that increasing intracellular levels of adenosine 3', 5'-cyclic monophosphate (cAMP) increases acetylcholine (ACh) release from airway parasympathetic nerves. Muscle strips from equine trachea were preincubated for 60 min with 10(-7)M atropine, 10(-6)M neostigmine, and 10(-5) M guanethidine. The ACh release was evoked by electrical field stimulation (EFS, 20 V, 0.5 ms, 0.5 Hz) and measured by high-performance liquid chromatography with electrochemical detection. Agents known to increase cAMP, i.e., forskolin (10(-6) - 10(-4) M), 8-bromoadenosine 3', 5'-cyclic monophosp...
Holcombe SJ, Beard WL, Hinchcliff KW.To investigate the effect of a mask and pneumotachograph on ventilation, respiratory frequency, and tracheal and nasopharyngeal pressures in horses running on a treadmill. Methods: Six horses ran at 50, 75, and 100% of the speed that resulted in maximum oxygen consumption, with and without a mask and pneumotachograph. Tracheal and pharyngeal inspiratory and expiratory pressures, respiratory frequency, and arterial blood gases were measured. Methods: Six Standardbred horses. Methods: Oxygen consumption was measured during an incremental exercise test to determine the speed that resulted in maxi...
Raidal SL, Love DN, Bailey GD.Tracheal mucociliary clearance was determined in horses by measuring the rostrad transport of the radiopharmaceutical 99mtechnetium-sulphur colloid following deposition on the tracheal epithelium by intratracheal injection. The effects of head position (head elevated to normal standing position vs head lowered) and of accumulated purulent secretions on tracheal mucociliary clearance were evaluated for the first time in the horse. In normal horses tracheal mucociliary clearance was greatly accelerated by lowering the head so that the cranial trachea was lower than the caudal trachea. Horses con...
Marble SL, Edens LM, Shiroma JT, Savage CJ.A 16-hour-old foal was examined because of subcutaneous emphysema, which began developing 3 hours after a routine delivery. Physical examination did not reveal soft-tissue or musculoskeletal trauma, and there were no skin injuries to explain the subcutaneous accumulation of air. Results of CBC and serum biochemical analysis were within reference limits, and findings on endoscopy of the pharyngeal area, trachea, and esophagus were within normal limits other than observation of dorsal pharyngeal compression. A pulmonary bulla, pneumomediastinum, and pneumothorax were detected on thoracic radiogr...
Olszewski MA, Robinson NE, Yu MF, Derksen FJ.During acute bouts of recurrent airway obstruction (heaves) in horses, neutrophils that are capable of increased production of reactive oxygen species accumulate in the airways. In the study reported here, the effect of hydrogen peroxide (H2O2; 1 microM to 0.1M), one of these reactive oxygen species products, on the responses of isolated trachealis muscle of horses was determined. Before and after incubation with H2O2, contractile responses to acetylcholine, electrical field stimulation (EFS), 127 mM KCl, and relaxation responses to isoproterenol and activation of the nonadrenergic noncholiner...
Dixon PM, Railton DI, McGorum BC.The majority of 270 adult horses with chronic pulmonary diseases had excessive volumes of respiratory secretions (RS) present in their trachea, elevated tracheal RS neutrophil ratios and lowered arterial oxygen partial pressures. Some control horses, had inexplicably elevated trachael RS neutrophil ratios. Only the chronic obstructive pulmonary disease (COPD) affected group had significantly elevated bronchoalveolar lavage fluid (BALF) neutrophil ratios. Maximal intrapleural pressure changes (max dPpl) were raised in 48% of COPD cases and rarely with other pulmonary disorders. Arterial pH or c...
Maxson AD, Soma LR, May LL, Martini JA.Effects of furosemide, exercise, and atropine on tracheal mucus transport rate (TMTR) in horses were investigated. Atropine (0.02 mg/kg of body weight) administered IV or by aerosolization significantly (P < 0.05) decreased TMTR at 60, but not at 30 minutes after its administration in standing horses. Furosemide (1.10 mg/kg, IV) did not have any significant effect on TMTR when measured at 2 or 4 hours after its administration in standing horses. Exercise alone or furosemide (1.10 mg/kg, IV) administration followed 4 hours later by exercise did not alter TMTR, compared with values for standi...
Maisi P, Paananen M, Koivunen AL.Seventeen trotters, eight healthy and nine with a mild respiratory disease, underwent a submaximal treadmill exercise. Heart rate, breathing frequency, intrapleural pressure difference (IP difference) as well as haematocrit and concentration of lactic acid in blood were monitored before exercise, during exercise and during recovery. The activities of beta-glucuronidase and plasmin, total proteolytic activity and trypsin inhibitory capacity were measured from the tracheal fluid before and after exercise. IP difference significantly increased during exercise and returned to normal values within ...
Golland LC, Hodgson DR, Davis RE, Rawlinson RJ, Collins MB, McClintock SA, Hutchins DR.A retrospective study of 46 horses with retropharyngeal lymph node (RPLN) infection presented to the Rural Veterinary Centre between 1977 and 1992 was undertaken. Horses aged less than one year were most commonly represented (46%). Thirty-nine percent of cases had been exposed to horses with confirmed or suspected strangles (Streptococcus equi subsp equi infection) within the previous 8 weeks. Most frequent signs were unilateral or bilateral swelling of the throat region (65%), respiratory stertor/dyspnoea (35%), purulent nasal discharge (20%), inappetence and signs of depression (15%), and dy...
McClure SR, Taylor TS, Honnas CM, Schumacher J, Chaffin MK, Hoffman AG.Permanent tracheal stomas were created in seven sedated, standing horses with severe upper airway obstruction. After local anesthesia, a 3-cm by 6-cm rectangle of skin was removed from the ventral surface of the neck, 3 cm distal to the cricoid cartilage. The sternothyrohyoideus muscles were clamped proximally and distally, then transected to expose the tracheal rings. The ventral third of four tracheal rings was dissected from the tracheal mucosa that was then incised in a double "Y." Two layers of suture were used to achieve mucocutaneous closure. Stomas healed without serious complications;...
Rehder RS, Ducharme NG, Hackett RP, Nielan GJ.To determine whether abnormal airway pressures have a role in development of dorsal displacement of the soft palate (DDSP), measurements of tracheal and pharyngeal pressures were correlated with nasopharyngeal morphology in exercising horses. Exercising videoendoscopy and measurement of tracheal and pharyngeal pressures were used in 14 clinically normal horses and 19 horses with intermittent DDSP. The pressure signals were superimposed on the videoendoscope image, and both images were saved simultaneously on a videocassette for slow motion analysis to determine the instant displacement occurre...
Zhang XY, Robinson NE, Wang ZW, Lu MC.We investigated the effects of catecholamines on acetylcholine (ACh) release from equine airway parasympathetic nerves. Trachealis strips were suspended in 2-ml tissue baths with Krebs-Henseleit solution containing atropine (10(-7) M), neostigmine (10(-6) M), and guanethidine (10(-5) M). Electrical field stimulation (20 V, 0.5 ms, 0.5 Hz, for 15 min) was applied, and ACh was measured by high-performance liquid chromatography with electrochemical detection. Epinephrine (Epi) and norepinephrine (NE) inhibited ACh release in a concentration-dependent manner. Inhibition was attenuated by the alpha...
Wang ZW, Yu MF, Robinson NE, Derksen FJ.The present study was conducted to determine if acetylcholine (ACh) release from airway cholinergic nerves is increased and if modulation of ACh release by prejunctional receptors is altered in horses with heaves, an obstructive airway disease characterized by airway inflammation and bronchospasm. Trachealis strips and bronchial segments of normal horses and horses affected with heaves were suspended in 2-ml tissue baths. ACh release was induced by electrical field stimulation and the bath ACh content was measured by high performance liquid chromatography (HPLC) with electrochemical detection....
Mair TS, Stokes CR, Bourne FJ.Mast cells in the equine respiratory mucosa were studied at both light--and transmission electron--microscope levels. Mast cells were identified at all levels of the tract, with the greatest cell density in the nasopharynx. The majority (57 to 94 per cent) of this cell population were located within the connective tissue of the lamina propria. Up to 20 per cent of these cells were associated with the mucosal glandular tissue, whilst small numbers were present within the surface epithelium and in association with nodular lymphoid tissue. In the peripheral lung tissue 20 per cent of the mast cel...
Traub-Dargatz JL, Ingram JT, Stashak TS, Kiper ML, Tarr S, Child G, MacAllister CG.Four Quarter Horse foals ranging in age from 6 days to 2 months were determined to have upper airway stridor secondary to polymyopathy suspected to be hyperkalemic periodic paralysis. Electromyography revealed spontaneous muscle activity in all muscles examined. Electromyographic findings were similar in the dams of 3 foals (No. 1, 3 and 4). Hyperkalemia was found in foals 1 and 4. Endoscopically, the upper airway stridor in foals 1 and 3 was confirmed to be attributable to laryngeal and pharyngeal collapse or spasm. Foals 1, 2, and 3 were treated with acetazolamide. Foal 4 was not treated, at...
Galati P, Roperto F, De Vico G, Restucci B, D'Andrea F.Specimens of the tracheal epithelium were obtained from two sites in nine healthy horses by a fibre optic endoscope. Electron microscopic examination of 53,550 cilia revealed that 5.2 per cent of cilia were atypical. Nine hundred and seventeen (1.7 per cent) were compound, 78 (0.15 per cent) were swollen, 27 (0.05 per cent) were intracytoplasmic and 171 (3.35 per cent) had microtubular defects. These microtubular defects (159 peripheral and 12 central) were found in 5103 cross-sectioned cilia.
Barber SM.A three year old Thoroughbred filly was examined because of bilateral nasal discharge and external swelling of the left laryngeal area. Endoscopy revealed an enlarged left arytenoid cartilage, left laryngeal hemiplegia and drainage of purulent material into the lumen of the larynx. Radiographs showed a large fluid and gas filled cavity overlying the caudal larynx and cranial trachea. Surgical drainage and debridement of the abscess led to complete healing by secondary intention. Laryngeal ventriculectomy was performed as a treatment for left laryngeal hemiplegia, but a grave prognosis for resp...
Golland LC, Hodgson DR, Davis RE, Rawlinson RJ, Collins MB, McClintock SA, Hutchins DR.A retrospective study of 46 horses with retropharyngeal lymph node (RPLN) infection presented to the Rural Veterinary Centre between 1977 and 1992 was undertaken. Horses aged less than one year were most commonly represented (46%). Thirty-nine percent of cases had been exposed to horses with confirmed or suspected strangles (Streptococcus equi subsp equi infection) within the previous 8 weeks. Most frequent signs were unilateral or bilateral swelling of the throat region (65%), respiratory stertor/dyspnoea (35%), purulent nasal discharge (20%), inappetence and signs of depression (15%), and dy...
Sweeney CR.Tracheal mucus transport rates were measured over a 10-minute period in 20 healthy horses twice in 24 hours. The mean rate was 1.93 +/- 0.55 cm/min on day 1 and 1.99 +/- 0.49 cm/min 24 hours later. The mean difference between day 1 and day 2 (0.06 +/- 0.42 cm/min) was not significant (P = 0.55). The range on day 1 was 1.12 to 2.9 cm/min and 1.11 to 2.89 cm/min on day 2.
Davis DM, Honnas CM, Hedlund CS, Schneiter HL.A 3-day-old Thoroughbred foal developed a large, air-distended, midcervical swelling that was diagnosed as a congenital tracheal bronchus with associated ectopic lung tissue. Clinical signs consisted of a compressible air-filled sac that enveloped the trachea. The nature and extent of the defect were evaluated endoscopically and radiographically. Surgical resection of the bronchus and associated air-filled sac resulted in a functionally and cosmetically acceptable outcome.
Yu MF, Ewaskiewicz JI, Adda S, Bailey K, Harris V, Sosnoski D, Tomasic M, Wilson J, Kotlikoff MI.We report adenovirus-mediated gene transfer into airway smooth muscle cells in cultured cells and organ-cultured tracheal segments. Incubation of cultured rat tracheal myocytes with virus (5 x 10(8) pfu/ml) for 6 h resulted in beta-galactosidase expression in 94.8 +/- 2.5% of cells (n = 4). Following incubation of thin (less than 200 microns diameter) equine trachealis muscle segments with virus in organ culture (5 x 10(8)-5 x 10(10) pfu/ml) the average expression of the Lac Z gene was approximately 19 +/- 10% (n = 9). Expression was markedly improved, however, in segments from neonatal rats (...
Nelson R, Hampe DW.Tracheal mucous transport rates were measured in 12 nonanesthetized horses after an intratracheal injection of 99mtechnetium-sulfur colloid. The transport rate of the subsequent bolus of radioactivity was determined, using a portable scaler rate meter fitted with a high-energy gamma-scintillation probe. A gamma-scintillation camera was used to verify bolus form and movement in 1 horse. The mean tracheal mucous transport rate was 1.66 +/- 0.24 cm/min.
Holcombe SJ, Beard WL, Hinchcliff KW, Robertson JT.The effect of transection of the sternothyroideus and sternohyoideus muscles on upper airway mechanics was investigated in exercising horses. Upper airway mechanics of six Standardbred horses were measured at rest and during exercise before and 24 h and 2 wk after sternothyrohyoid myectomy. Transnasal tracheal and pharyngeal catheters connected to differential pressure transducers were used to measure tracheal and pharyngeal pressures. A pneumotachograph mounted on the rostral end of an airtight face mask was used to measure airflow. Horses ran at 50, 75, and 100% of maximal O2 consumption on ...
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.
Maxson AD, Soma LR, May LL, Martini JA.Effects of furosemide, exercise, and atropine on tracheal mucus transport rate (TMTR) in horses were investigated. Atropine (0.02 mg/kg of body weight) administered IV or by aerosolization significantly (P < 0.05) decreased TMTR at 60, but not at 30 minutes after its administration in standing horses. Furosemide (1.10 mg/kg, IV) did not have any significant effect on TMTR when measured at 2 or 4 hours after its administration in standing horses. Exercise alone or furosemide (1.10 mg/kg, IV) administration followed 4 hours later by exercise did not alter TMTR, compared with values for standi...
Abraham G, Kottke C, Ungemach FR.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...
Scott EA.A weanling Quarter Horse filly developed ventral swelling of the lower cervical area after difficult passage of a stomach tube for deworming. Intermittent bilateral nasal discharge developed. Radiography revealed fluid and gas density dorsal to the trachea and esophagus. Surgical incision with drainage and debridement of the abscess and fistulous tract, facilitated by use of drains, led to complete recovery. Contrast medium injected after surgery demonstrated a communication between the abscess and the pharyngeal region.
Trim CM.Complications following the use of the cuffless large animal endotracheal tube during general anesthesia in 2 horses are reported. One horse developed laryngeal edema during recovery. The edema was treated successfully with dexamethasone, but severe laryngeal trauma was confirmed 24 hours later at necropsy. The second horse had a swollen tongue and had difficulty eating for 3 days after anesthesia. The condition resolved without treatment. this report is a reminder of the potential damage which can occur from endotracheal intubation.
Dougherty SS, Palmer JL.A 4-year-old horse was evaluated for chronic coughing, mucopurulent nasal discharge, and failure to thrive. Results: Endoscopy was performed on the larynx, pharynx, and trachea and revealed an approximately 2-cm fluctuant subepiglottic cyst. Results: The subepiglottic cyst was treated with intralesional formalin administration. Following 2 injections, 2 weeks apart, the cyst was completely resolved with no evidence of scarring or epiglottic deformity. Conclusions: Findings suggest that intralesional formalin administration for treatment of subepiglottic cysts may be a minimally invasive, econo...
Dixon PM.The structure and possible functions of respiratory secretions are reviewed. In the equine, goblet (mucus producing) cells are the main source but little information is available on the volume or composition of equine respiratory secretions. Airway mucus has complex and incompletely understood physical characteristics which can be partially assessed by a wide range of in vitro and biological techniques. The complex relationship between mucus structure and its propulsion by the airway cilia are discussed, both in health and with pulmonary disease. Mucokinesis in the horse has been assessed visu...
Barnett TP, Hawkes CS, Dixon PM.To report a resection and anastomosis technique to treat trauma-induced tracheal stenosis. Methods: Case report. Methods: A 9-year-old Warmblood gelding. Methods: Endoscopy, radiography, and ultrasonography were used to diagnose a single ring tracheal stenosis; the stenotic region was resected and adjacent tracheal rings anastomosed with an end-to-end technique. Results: The anastomosis healed completely despite formation of a unilateral partial mucosal stenosis "web," which was subsequently removed by transendoscopic laser surgery. During tracheal anastomosis, the left recurrent laryngeal ner...
Eyre P, Gaviller P, Thorsen J.Groups of guinea-pigs were vaccinated with equine influenza A-1 virus and helically-cut tracheal strips were subsequently contracted to carbachol (EC50) and relaxed to isoprenaline at 3, 5 and 10 days post-vaccination. Tracheas from another group were contracted to phenylephrine in the presence of propranolol. Compared to controls, responses to isoprenaline in virus-infected tracheas were significantly potentiated at days 3 and 10. Virus infection significantly inhibited tracheal responsiveness to phenylephrine. It appears that enhancement of isoprenaline may be caused by diminished reactivity...
Roethlisberger-Holm K.Recording of intratracheal pressure during exercise as a method for evaluating upper airway obstruction in the horse has previously been carried out on the treadmill. In the present study the method was applied to normal horses, outdoors under field conditions, to assess its usefulness for analysis of respiratory problems mainly occurring under racing conditions. The horses examined performed a standardized exercise test during which the intratracheal pressure was recorded with a tape recorder receiving amplified signals from a transducer connected to a percutaneously inserted intratracheal ca...
Brock KA.A pharyngeal performation, probably associated with endotracheal intubation, occurred in a healthy 4 1/2-month-old colt. Inhalation anesthesia was carried out for elective surgery, but acute cervical cellulitis, pleuritis, and pneumonia developed after the surgery. Antibacterial and supportive therapy was ineffective.
Kilgué A, Teudt IU, Grundmann T, Püschel K.Every blunt laryngeal trauma requires examination by an ENT physician and may necessitate observation for a number of hours. The literature shows a heterogeneous picture regarding airway management (tracheotomy vs. intubation). Extremely violence forces such as horse kicks require a tracheotomy, as demonstrated by case studies. In such cases, a high level of responsibility lies with the emergency physician providing the initial treatment. We present the case of a 37-year-old horse trainer, who suffered a horse kick to the larynx with a complex laryngeal fracture. Intubation of the patient by t...
Tulamo RM, Maisi P.To establish concentration of hyaluronate (HA) in tracheal lavage fluid from healthy horses and horses with chronic obstructive pulmonary disease (COPD). ANIMALS AND SAMPLES: Tracheal lavage fluid samples (n = 42) from 18 horses, 11 with COPD, and 7 control horses. Methods: Clinical examination of the respiratory tract, tracheal lavage, and blood sample collection were performed on horses without clinical signs of respiratory tract disease and horses with clinical signs of COPD. In some horses, 1 to 5 repeated examinations were performed at 1-week intervals. Tracheal lavage fluid samples were ...
Traub-Dargatz JL, McKinnon AO, Thrall MA, Jones RL, Bruyninckx W, Blancquaert AM, Dargatz DA.We evaluated the efficacy of 3 treatments for chronic obstructive pulmonary disease in horses: prednisone (400 mg/horse, PO, daily; n = 7), methyl sulfonmethane (10 g/horse, PO, q 12 h; n = 6), and clenbuterol hydrochloride (0.4 mg/horse, PO, q 12 h; n = 7). A fourth group acted as controls (n = 6) and was not treated. The treatment period lasted 10 days. Each horse was a member of 2 different groups for 10 days, separated by an 18-day interval of no treatment. All horses were housed together in an outdoor pen without bedding. Horses were fed alfalfa/grass hay mix ad libitum from a large feede...
Holcombe SJ, Derksen FJ, Stick JA, Robinson NE, Boehler DA.To compare tracheal and pharyngeal inspiratory and expiratory pressures achieved during 60 seconds of nasal occlusion in standing horses with pressures achieved in horses during intense exercise. Methods: 5 Standardbreds. Methods: Tracheal and pharyngeal inspiratory and expiratory pressures were obtained from 5 horses during 60 seconds of nasal occlusion and compared with tracheal and pharyngeal pressures achieved during incremental treadmill exercise tests in which horses ran at 50, 75, and 100% of the speed that resulted in maximal heart rate (HRmax). Results: Significant difference was not ...
Thorsen J, Willoughby RA, McDonell W, Valli VE, Viel L, Bignell W.Samples of mucus from the lower trachea were collected from 53 horses with chronic obstructive pulmonary disease and from 24 clinically normal horses. Serum samples were collected from 35 of the horses with chronic obstructive pulmonary disease and from the 24 normal horses. Samples were tested for inhibition of hemagglutination by influenza A equine 1 and 2 viruses. There were high levels of hemagglutination inhibiting activity against influenza A equine 1 in mucus samples from horses with chronic obstructive pulmonary disease.
Tessier GJ, Traynor TR, Kannan MS, O'Grady SM.When the equine tracheal epithelium is mounted in Ussing chambers and bathed in plasma-like Ringer solution, the tissue generates a lumen-negative transepithelial potential (PD) of 22 mV and a short-circuit current (Isc) of 70-200 microA/cm2. Mucosal addition of 10 microM histamine produces a transient increase in the Isc followed by a return to baseline or below. Mucosal addition of 2 microM diphenhydramine inhibits the Isc response to mucosal histamine, whereas 100 microM mucosal cimetidine produces no effect. The average initial increases in Isc over time for mucosal vs. serosal histamine a...
Tate LP, Koch DB, Sembrat RF, Boles CL.A surgical technique for resection of a portion of the trachea followed by end-to-end anastomosis was developed on 4 clinically normal horses. The trachea healed without complications in 3 of the horses in which 3 tracheal cartilages were removed. Five tracheal cartilages were removed from the 4th horse. It had to be euthanatized because of excessive suture line tension and wound disruption, which occurred during recovery from anesthesia. Suture line tension was measured on 3 other clinically normal horses positioned in dorsal recumbency immediately after euthanasia after 3 and 5 tracheal cart...
Every LJ, Hostnik ET, Hostnik LD, Yardley J, Shore-Khirallah AT, Thompson A, Linn SC.Tracheal collapse in horses is reportedly uncommon; however, American Miniature Horses are more commonly affected. There is no description of the tracheal luminal diameter of American Miniature Horses, making early detection of tracheal luminal narrowing difficult. Objective: To 1) describe radiographic tracheal luminal diameter in clinically normal American Miniature Horses, 2) report the prevalence of subclinical tracheal collapse in a population of American Miniature Horses, and 3) use tracheal videofluoroscopy to quantify variation in tracheal luminal diameter throughout the respiratory c...
Lehner AF, Harkins JD, Karpiesiuk W, Woods WE, Robinson NE, Dirikolu L, Fisher M, Tobin T.Clenbuterol is a beta2 agonist/antagonist bronchodilator, and its identification in post-race samples may lead to sanctions. The objective of this study was to develop a specific and highly sensitive serum quantitation method for clenbuterol that would allow effective regulatory control of this agent in horses. Therefore, clenbuterol-d9 was synthesized for use as an internal standard, an automated solid-phase extraction method was developed, and both were used in conjunction with a multiple reaction monitoring liquid chromatography-tandem mass spectrometry (LC-MS-MS) method to allow unequivoca...
