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.
Steffey EP, Mama KR, Brosnan RJ, Imai A, Maxwell LK, Cole CA, Stanley SD.To compare characteristics of horses recovering from 4 hours of desflurane anesthesia with and without immediate postanesthetic IV administration of propofol and xylazine. Animals-8 healthy horses (mean +/- SEM age, 6.6 +/- 1.0 years; mean body weight, 551 +/- 50 kg). Methods: Horses were anesthetized twice. Both times, anesthesia was induced with a combination of xylazine hydrochloride, diazepam, and ketamine hydrochloride and then maintained for 4 hours with desflurane in oxygen. Choice of postanesthetic treatment was randomly assigned via a crossover design such that each horse received an ...
Gerber V, Baleri D, Klukowska-Rötzler J, Swinburne JE, Dolf G.Mode of inheritance of equine recurrent airway obstruction (RAO) is unknown. Objective: Major genes are responsible for RAO. Methods: Direct offspring of 2 RAO-affected Warmblood stallions (n = 197; n = 163) and a representative sample of Swiss Warmbloods (n = 401). Methods: One environmental and 4 genetic models (general, mixed inheritance, major gene, and polygene) were tested for Horse Owner Assessed Respiratory Signs Index (1-4, unaffected to severely affected) by segregation analyses of the 2 half-sib sire families, both combined and separately, using prevalences estimated in a representa...
Christmann U, Hite RD, Witonsky SG, Elvinger F, Werre SR, Thatcher CD, Tan RH, Buechner-Maxwell VA.Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown. Objective: To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant. Methods: Seventeen healthy horses 6-25 years of age maintained on pasture year-round. Methods: BALF was collected by standard procedures and w...
Leprêtre PM, Metayer N, Giovagnoli G, Pagliei E, Barrey E.Measurements of minute ventilation (VE) and expired oxygen and carbon dioxide fractions (FeO2 and FeCO2) were measured at rest and during exercise in seven warmblood horses performing two consecutive standardised incremental treadmill exercise tests at submaximal speed, using the portable K4b2 telemetric unit and the laboratory Quark metabolic cart in random order. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were estimated using the Haldane equation. There were no significant differences between the measurements made with the two devices. However, VE was overestimated when th...
Castanheira M, Paiva SR, Louvandini H, Landim A, Fiorvanti MC, Paludo GR, Dallago BS, McManus C.The environment in which the horse is reared affects its ability to maintain thermal balance which is in turn related to thermal characteristics and regulatory physiological mechanisms. In this study a multivariate analysis of physiological traits in relation to heat tolerance in horses was carried out in the Federal District, Brazil. The aim was to test the ability of these analyses to separate groups of animals and determine which physiological traits are most important in the adaptation to heat stress. Forty adult horses (4 to 13 years) were used, ten from each of four different genetic gro...
Perkins JD, Windley Z, Dixon PM, Smith M, Barakzai SZ.To evaluate the use of sinoscopy for detection and treatment of ventral conchal sinus (VCS) and/or rostral maxillary sinus (RMS) disease in horses. Methods: Case series Methods: Horses (n=60) with suspected paranasal sinus disease. Methods: Horses were evaluated by sinoscopy through a conchofrontal sinus (CFS) portal with ventral conchal bulla (VCB) fenestration. Other endoscopic sinus approaches and adjunctive diagnostic tests; oral examination, computed tomography, radiography, scintigraphy and endoscopic examination of the upper portion of the respiratory tract were used in some horses. Res...
Hinchcliff KW, Morley PS, Guthrie AJ.To evaluate the efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage (EIPH) in Thoroughbred racehorses under typical racing conditions. Methods: Randomized, placebo-controlled, blinded, crossover field trial. Methods: 167 Thoroughbred racehorses. Methods: Horses were allocated to race fields of 9 to 16 horses each and raced twice, 1 week apart, with each of the 2 races consisting of the same race field and distance. Each horse received furosemide (500 mg, IV) before one race and a placebo (saline solution) before the other, with the order of treatments randomly determ...
Pollock PJ, Reardon RJ, Parkin TD, Johnston MS, Tate J, Love S.There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. Objective: To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. Methods: Horses were selected randomly from ...
Perkins JD, Salz RO, Schumacher J, Livesey L, Piercy RJ, Barakzai SZ.The extent to which variability affects endoscopic grading of arytenoid cartilage movement is uncertain. Objective: To determine the observer and within horse variability of grading arytenoid cartilage movement in horses during resting endoscopic examination, using a 7-grade system. Methods: Endoscopic recordings of the upper respiratory tract made at rest in 270 draught horses were reviewed independently by 2 veterinarians to assess interobserver variability when scoring horses' laryngeal function with a 7-grade system. Grading was repeated by both examiners in 80 randomly selected recordings...
Desmaizieres LM, Serraud N, Plainfosse B, Michel A, Tamzali Y.High speed treadmill endoscopy provides a true assessment and diagnosis of the dynamic obstructions of the upper equine respiratory tract (DO-URT). However, treadmills do not always allow reproduction of the exact conditions of dynamic collapse of the URT. The availability of on-board endoscopes, which could be used without a treadmill, would make exercising endoscopy readily available to more equine practices. Objective: To develop and validate an innovative endoscope which could be used for the examination of the URT at exercise in ridden and harnessed sport horses performing in natural cond...
Enderle AK, Levionnois OL, Kuhn M, Schatzmann U.To compare isoflurane alone or in combination with systemic ketamine and lidocaine for general anaesthesia in horses. Methods: Prospective, randomized, blinded clinical trial. Methods: Forty horses (ASA I-III) undergoing elective surgery. Methods: Horses were assigned to receive isoflurane anaesthesia alone (ISO) or with ketamine and lidocaine (LKI). After receiving romifidine, diazepam, and ketamine, the isoflurane end-tidal concentration was set at 1.3% and subsequently adjusted by the anaesthetist (unaware of treatments) to maintain a light plane of surgical anaesthesia. Animals in the LKI ...
Schauvliege S, Van den Eede A, Duchateau L, Gasthuys F.To evaluate the combined effects of enoximone and dobutamine on the cardiovascular system and respiratory gas exchange in isoflurane-anaesthetized ponies. Methods: Prospective, randomized, experimental study. Methods: Six ponies (286 +/- 52 kg), aged 5.0 +/- 1.6 years. Methods: After sedation (romifidine 80 microg kg(-1)), anaesthesia was induced with midazolam (0.06 mg kg(-1)) and ketamine (2.2 mg kg(-1)) and maintained with isoflurane in oxygen. The ponies were ventilated to maintain eucapnia. After 90 minutes (=T0), enoximone alone (0.5 mg kg(-1)) (E) or enoximone, followed by a constant ra...
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.
Cheetham J, Pigott JH, Hermanson JW, Campoy L, Soderholm LV, Thorson LM, Ducharme NG.The equine upper airway is highly adapted to provide the extremely high oxygen demand associated with strenuous aerobic exercise in this species. The tongue musculature, innervated by the hypoglossal nerve, plays an important role in airway stability in humans who also have a highly adapted upper airway to allow speech. The role of the hypoglossal nerve in stabilizing the equine upper airway has not been established. Isolated tongues from eight mature horses were dissected to determine the distal anatomy and branching of the equine hypoglossal nerve. Using this information, a peripheral nerve ...
Richard EA, Fortier GD, Lekeux PM, Van Erck E.Any disorder impairing a performance horse's ability to ventilate its lungs and exchange oxygen compromises exercise performance in any discipline. Since bronchoalveolar lavage was described in horses in the early 1980s, laboratory evaluation of respiratory fluids, along with clinical and functional assessment of the respiratory system, has become a relevant step in the diagnosis of respiratory disease affecting performance. The aim of this review is to provide objective information to assist clinicians in interpreting laboratory findings by (1) summarising published cytological references val...
Elfman L, Riihimäki M, Pringle J, Wålinder R.Many people spend considerable amount of time each day in equine stable environments either as employees in the care and training of horses or in leisure activity. However, there are few studies available on how the stable environment affects human airways. This study examined in one horse stable qualitative differences in indoor air during winter and late summer conditions and assessed whether air quality was associated with clinically detectable respiratory signs or alterations to selected biomarkers of inflammation and lung function in stable personnel. Methods: The horse stable environment...
Duz M, Whittaker AG, Love S, Parkin TD, Hughes KJ.Measurement of hydrogen peroxide (H(2)O(2)) concentration and pH in exhaled breath condensate (EBC) is useful for detection and monitoring of asthma in humans. In contrast, limited information on the use of these parameters for the investigation of lower airway inflammation (LAI) is available for horses. Aims of the current study were to investigate the intra- and inter-day variations of EBC H(2)O(2) concentration and pH in horses and establish any relationship(s) with LAI. Both intra- and inter-day variability of EBC H(2)O(2) concentration were large, while those of pH were small. No signific...
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 ...
Witte TH, Mohammed HO, Radcliffe CH, Hackett RP, Ducharme NG.The success of combined prosthetic laryngoplasty with ipsilateral ventriculocordectomy (LPVC) has not been compared to that of partial arytenoidectomy (PA) in a clinical population. Objective: In Thoroughbred (TB) racehorses: (1) earnings after LPVC are unaffected by the severity of recurrent laryngeal neuropathy (RLN) (laryngeal grade III vs. grade IV); (2) LPVC and PA yield similar results in the treatment of grade III RLN; (3) performance outcome following PA is independent of diagnosis (RLN vs. unilateral arytenoid chondritis [UAC]); and (4) neither LPVC nor PA returns horses to the level ...
Barakzai SZ, Boden LA, Hillyer MH, Marlin DJ, Dixon PM.Previously, objective comparisons of surgical procedures to relieve dorsal displacement of the soft palate (DDSP) have been limited by the presumptive basis of the diagnostic measures applied. Objective: To assess and compare the efficacy of thermal cautery surgery to conservatively treated controls in racehorses definitively diagnosed with idiopathic intermittent DDSP. Objective: Both conservative and surgical treatments have a beneficial result on racing performance in racehorses affected with DDSP. Methods: Race records were obtained for Thoroughbred racehorses definitively diagnosed with D...
Hajek P, Ungemach FR, Abraham G.Muscarinic acetylcholine receptor (mAChR)-mediated guanine nucleotide-binding regulatory protein (G protein) activation and the functional interaction between receptors and the respective G proteins were investigated using an agonist-induced [(35)S]guanosine-5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS)-binding approach in membranes of 3 native equine airway segments (trachea, bronchus and lung), which differ tremendously in mAChR density and subtype distribution; especially subtypes that couple negatively to adenylyl cyclase through G(i/0) proteins, i.e. M(2) receptors. The assay was initi...
Katavolos P, Ackerley CA, Viel L, Clark ME, Wen X, Bienzle D.Horses are prone to recurrent airway obstruction (RAO), an inflammatory lung disease induced by repeated exposure to environmental mold, dust, and bacterial components. Active disease manifests with mucus hyperproduction, neutrophilic inflammation, bronchoconstriction, and coughing. Chronically affected animals have lung remodeling characterized by smooth muscle hyperplasia, collagen deposition, lymphoid hyperplasia, and impaired aerobic performance. Clara cell secretory protein (CCSP) counters inflammation in the lung, hence we hypothesized that CCSP depletion is a key feature of RAO in horse...
Ainsworth DM, Matychak M, Reyner CL, Erb HN, Young JC.To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on chemokine and cell-surface receptor (CSR) gene expression in primary bronchial epithelial cell cultures (BECCs) established from healthy horses and horses with recurrent airway obstruction (RAO). Methods: BECCs established from bronchial biopsy specimens of 6 RAO-affected horses and 6 healthy horses. Methods: 5-day-old BECCs were treated with PBS solution, hay dust solutions, LPS, or beta-glucan for 6 or 24 hours. Gene expression of interleukin (IL)-8, chemokine (C-X-C motif) ligand 2 ...
Schauvliege S, Van den Eede A, Duchateau L, Pille F, Vlaminck L, Gasthuys F.To investigate the influence of calcium chloride (CaCl(2)) on the cardio-respiratory effects of enoximone in isoflurane anaesthetized ponies. Methods: Prospective consecutive experimental trial. Animals Six healthy ponies, weighing 287 +/- 55 kg were included in this study. Methods: After sedation (romifidine, 80 microg kg(-1)), anaesthesia was induced with midazolam (0.06 mg kg(-1)) and ketamine (2.2 mg kg(-1)) and maintained with isoflurane in oxygen. The ponies' lungs were ventilated to maintain normocapnia. After 90 minutes, a bolus of enoximone (0.5 mg kg(-1)) was administered, followed b...
Elfenbein JR, Sanchez LC, Robertson SA, Cole CA, Sams R.To evaluate the effects of detomidine on visceral and somatic nociception, heart and respiratory rates, sedation, and duodenal motility and to correlate these effects with serum detomidine concentrations. Methods: Nonrandomized, experimental trial. Methods: Five adult horses, each with a permanent gastric cannula weighing 534 +/- 46 kg. Methods: Visceral nociception was evaluated by colorectal (CRD) and duodenal distension (DD). The duodenal balloon was used to assess motility. Somatic nociception was assessed via thermal threshold (TT). Nose-to-ground (NTG) height was used as a measure of sed...
Portier KG, Jaillardon L, Leece EA, Walsh CM.To evaluate the effects of local anaesthesia with lidocaine for castration of horses under intravenous anaesthesia. Methods: Prospective, randomized, blinded clinical trial. Methods: Fifteen equidae, scheduled to undergo castration under total intravenous anaesthesia, were randomly distributed in two groups. One group received lidocaine injections (group L: two ponies, four horses, two donkeys) and the other received saline (group S: two ponies, three horses, two donkeys). Methods: Behaviour, heart rate (HR) and respiratory rate (f(R)) were evaluated prior to anaesthesia. Body mass was measure...
Kollias-Baker C, Cox K, Jones J.Omeprazole is a proton-pump inhibitor recently approved in the United States for the treatment of gastric ulcer disease in horses. A study was designed to determine the effects of omeprazole treatment on the physiological indices of performance of horses during incremental treadmill exercise. In a crossover-design study carried out over 2 weeks, five horses completed standardized incremental exercise tests on a high-speed treadmill either with no treatment or treatment with omeprazole. No statistically significant effects of omeprazole were found on the mean maximum responses for specific oxyg...
Hawkins JF, Tulleners EP, Ross MW, Evans LH, Raker CW.The purpose of this study was to examine the influence of laryngoplasty on racing performance and to determine if any of the following variables had a significant effect on outcome: breed (Thoroughbred v Standardbred), endoscopic grade of laryngeal function, ventriculectomy versus no ventriculectomy, type of prosthetic suture used, and number of prostheses placed. Methods: Retrospective study of laryngoplasty with or without ventriculectomy for treatment of left laryngeal hemiplegia in racehorses between 1986 and 1993. Methods: 230 horses (174 Thoroughbreds, 56 Standardbreds). Methods: The med...
Sellon DC, Papich MG, Palmer L, Remund B.A two-way cross-over study of the pharmacokinetics of butorphanol after intravenous and intramuscular administration at 0.08 mg/kg in six adult horses was performed. Heparinized venous blood samples were obtained prior to drug administration and at 10, 20, 30, 45, 60, 120, 180, 240, and 360 min after IV injection. Samples were obtained at the same time points and at 6 h and 12 h after IM injection. Physical examination parameters were recorded at each time point. Plasma butorphanol concentrations were determined by high performance liquid chromatography. No significant differences in any physi...
Whitehair KJ, Willits NH.To identify factors associated with various arterial partial pressures of oxygen (Pao2) in anesthetized horses. Methods: Retrospective study. Methods: 1,450 horses anesthetized a total of 1,610 times with isoflurane or halothane. Methods: Anesthesia records, particularly results of blood gas analyses, were reviewed, and horses were grouped on the basis of lowest Pao2. Results: For horses with lowest Pao2 < 120 mm Hg, those with low pulse pressure, that underwent anesthesia on an emergency basis, or that were males were more likely to have Pao2 < 80 mm Hg. For horses with lowest Pao2 <...
Pelletier N, Leith DE.Thoroughbred horses (TB) have no ventilatory response to added CO2 during near-maximal exercise. To see whether that reflects mechanical limits to ventilation or the control of breathing, we examined the effects of varying inspired O2 fraction (0.16, 0.21, or 0.30) in five normal TB standing quietly and galloping at 10 and 14 m/s on a level treadmill. We measured gas exchange (O2 consumption and CO2 production) and ventilation with a flow-through mask system. We also measured PO2, PCO2, and O2 contents in arterial and mixed venous blood and calculated cardiac output by using the Fick equation....
Hobo S, Matsuda Y, Yoshida K.A total of 350 thoroughbred racehorses found clinically as having coughs or abnormal breath sounds underwent endoscopic examination of the upper respiratory tract at rest. As a result, abnormal endoscopic findings were obtained in all horses, demonstrating that thoroughbred racehorses with a clinical abnormality in the respiratory system necessarily had disorders in the upper respiratory tract. Whereas 11 types of disorder were observed, a combination of three different types of disorder were found in the highest frequencies in 3-, 4- and 5-year-old horses (27.8%, 29.2% and 29.7%, respectively...
Hovda T, Love L, Chiavaccini L.Hypoxaemia is a common concern during equine general anaesthesia. The prevalence and predictors of hypoxaemia in horses undergoing elective anaesthesia in particular are poorly documented. Objective: To determine and compare the prevalence of hypoxaemia (defined as PaO2 ≤ 80 mm Hg, on the lowest value recorded) in horses undergoing anaesthesia for exploratory laparotomy and elective procedures, and to identify risk factors in both subpopulations. Methods: Retrospective cohort study. Methods: Data were collected from 774 records of 708 horses undergoing general anaesthesia between April 2...
Schöniger S, Roschanski N, Rösler U, Vidovic A, Nowak M, Dietz O, Wittenbrink MM, Schoon HA.Pyogranulomatous rhinitis associated with an algal infection was diagnosed in a 25-year-old gelding and a 23-year-old mare had necrotizing sinusitis with intralesional algae and pigmented fungi. Algae were identified immunohistochemically in both cases as Prototheca spp. In the gelding, further characterization by polymerase chain reaction and sequencing revealed that the organism was Prototheca zopfii genotype 2. Fungi from the mare were identified as Pithomyces chartarum by molecular analysis. Prototheca species are achlorophyllous algae and P. chartarum represents a dematiaceous fungus; the...
Andrade FS, Facó LL, Ida KK, Silva LC, Fantoni DT, Ambrósio AM.To compare static compliance (C) and alveolar-arterial oxygen tension difference [P(a-a)O] between positive end-expiratory pressures (PEEP) of 7, 12 and 17 cmHO applied after an alveolar recruitment maneuver (RM) in isoflurane-anesthetized horses. Methods: Prospective, randomized, clinical study. Methods: A group of 30 healthy adult horses undergoing arthroscopic surgery. Methods: Animals in dorsal recumbency and mechanically ventilated with a tidal volume of 14 mL kg and 7 cmHO PEEP (control; n = 6) were subjected to an RM by increasing PEEP from 7 to 22 cmHO in 5 cmHO increments at 5 minute...
Mama KR, Pascoe PJ, Steffey EP, Kollias-Baker C.To characterize responses associated with two 1-hour total intravenous anesthesia techniques in horses. Methods: 6 mature, healthy mares. Methods: Each horse was anesthetized 3 times. Treatment order was determined by a series of Latin squares. After baseline measurements and instrumentation, horses were given xylazine (XYL) i.v.; anesthesia was induced 5 minutes later with 10% guaifenesin given i.v., then either ketamine (KET) or propofol (PRO) was given i.v. After anesthesia induction, each horse received an infusion of XYL and either KET or a low or high dose of PRO. Cardiopulmonary variabl...
Reardon RJ, Fraser BS, Heller J, Lischer C, Parkin T, Bladon BM.There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). Objective: To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. Objective: Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. Methods: The incl...
Kirschvink N, Di Silvestro F, Sbaï I, Vandenput S, Art T, Roberts C, Lekeux P.This study aimed to test whether shredded cardboard is an appropriate minimum-dust bedding material for heaves-affected horses. Results of standardized in vitro measurement of airborne dust and aeroallergen concentrations of cardboard bedding were significantly lower than those of common bedding materials. Six heaves-affected horses in clinical remission after pasturing were stabled for two months on cardboard bedding and fed grass silage. Pulmonary function tests (PFT: ventilatory mechanics, arterial blood gases, airway inflammation scoring, bronchoalveolar cytology) were performed before, du...
Murphy JR, McPherson EA, Dixon PM.The effects of the bronchodilator drugs, atropine, isoprenaline and terbutaline, on normal horses and on horses affected with chronic obstructive pulmonary disease (COPD), were assessed by pulmonary function tests and clinical examination. Normal horses were not affected but COPD horses responded by a marked decrease in intrathoracic pressure, a decrease in respiratory rate, an initial decrease followed by an increase in arterial oxygen partial pressure and clinical improvement after treatment with all 3 drugs. These changes were temporary.
Carregaro AB, Ueda GI, Censoni JB, Bisetto SP, Alonso BB, Reginato GM.The aim of this study was to compare the effects of methadone combined with detomidine or acepromazine on the quality of sedation and its influence over dissociative anesthesia in healthy horses. In a crossover design, seven horses were administered with 0.1 mg/kg methadone and 0.02 mg/kg detomidine intravenously (group MD) or 0.1 mg/kg methadone and 0.05 mg/kg acepromazine intravenously (group MA). Subsequently, anesthesia was induced with a combination of 2.2 mg/kg ketamine and 0.1 mg/kg midazolam intravenously. Descriptive scales and footages were used to evaluate the quality of sedat...
Costa LR, Eades SC, Venugopal CS, Moore RM.Summer pasture-associated recurrent airway obstruction (SPA-RAO), a seasonal airway obstructive disease of horses, is characterized by clinical exacerbation after exposure to pasture during warm months of the year. Endothelin (ET)-1, potent bronchoconstrictor, mitogen, secretagogue, and proinflammatory mediator, has been implicated in the pathogenesis of asthma and equine heaves. Objective: Immunoreactive ET-1 concentrations increase during clinical exacerbation and return to basal values during periods of disease remission. Methods: Twelve horses, 6 affected with SPA-RAO and 6 nonaffected. Me...
Benmansour P, Husulak ML, Bracamonte JL, Beazley SG, Withnall E, Duke-Novakovski T.To examine the cardiopulmonary effects of infusions of remifentanil or morphine, and their influence on recovery of horses anesthetized with isoflurane and dexmedetomidine. Methods: Randomized crossover study with 7-day rest periods. Methods: Six adult horses (507 ± 61 kg). Methods: After the horses were sedated with xylazine, anaesthesia was induced with ketamine and diazepam, and maintained with isoflurane. After approximately 60 minutes, a dexmedetomidine infusion was started (0.25 μg kg(-1) then 1.0 μg(-1) kg(-1) hour(-1) ) in combination with either saline (group S), morphine (0.15 mg ...
Chand N, Eyre P.Nonsteroidal anti-inflammatory drugs inhibit the biosynthesis of kinins and prostaglandins and stabilize leukocyte lysosomal membranes. Nonsteroidal anti-inflammatory drugs also weakly block the biosynthesis of histamine and serotonin, and pharmacologically antagonize kinins, prostaglandins and slow-reacting substance of anaphylaxis. Nonsteroidal anti-inflammatory drugs effectively control both cardiovascular and respiratory manifestations of hypersensitivity in cattle and horses. This, coupled with the contrasting lack of effectiveness of "antiamine" drugs, suggests that bio-amines such as hi...
Desmaizieres LM, Serraud N, Plainfosse B, Michel A, Tamzali Y.High speed treadmill endoscopy provides a true assessment and diagnosis of the dynamic obstructions of the upper equine respiratory tract (DO-URT). However, treadmills do not always allow reproduction of the exact conditions of dynamic collapse of the URT. The availability of on-board endoscopes, which could be used without a treadmill, would make exercising endoscopy readily available to more equine practices. Objective: To develop and validate an innovative endoscope which could be used for the examination of the URT at exercise in ridden and harnessed sport horses performing in natural cond...
Abdel Ghafar MA, Abdelraouf OR, Abdel-Aziem AA, Elnegamy TE, Mohamed ME, Yehia AM, Mousa GS.Idiopathic scoliosis is a common spinal malalignment that negatively impacts the respiratory system and physical conditioning in adolescents. Equine-assisted therapy comprises therapeutic horseback riding that optimizes physical performance and mobility in a range of contexts. However, the influence of equine-assisted therapy on pulmonary function remains unclear. Objective: To examine the impact of 10 weeks of hippotherapy combined with Schroth exercises on pulmonary function and aerobic capacity in adolescents with idiopathic scoliosis. Methods: A randomized controlled trial including 45 pat...
Derksen FJ, Williams KJ, Uhal BD, Slocombe RF, de Feijter-Rupp H, Eberhart S, Berney C, Robinson NE.Exercise-induced pulmonary haemorrhage (EIPH) occurs in the majority of horses performing strenuous exercise. Associated pulmonary lesions include alveolar and airway wall fibrosis, which may enhance the severity of EIPH. Further work is required to understand the pulmonary response to blood in the equine airways. Objective: To confirm that a single instillation of autologous blood into horse airways is associated with alveolar wall fibrosis, and to determine if blood in the airways is also associated with peribronchiolar fibrosis. Methods: Paired regions of each lung were inoculated with bloo...
Barakzai SZ, Boden LA, Dixon PM.To evaluate the effect of laryngoplasty (LP) on race performance in longer distance (National Hunt) Thoroughbred racehorses. Methods: Case-control study. Methods: National Hunt Thoroughbred racehorses (n=71) and race-matched controls (n=126). Methods: Race records for National Hunt racehorses that had LP and ventriculocordectomy were analyzed and racing performance was compared with race-matched controls. Results: Sixty-three of 71 cases were matched with controls. Postoperatively, 78% of cases raced, 47% improved their individual performance and cases were as likely to start in 1 or 3 races a...
Stopyra A, Sobiech P, Waclawska-Matyjasik A.The acid-base equilibrium is closely linked to gas exchange in the lungs, and respiratory exchange ratios are used to evaluate respiratory effectiveness and tissue oxygen levels. Acid-base indicators are determined in both arterial and venous blood samples. This study compares the usefulness of acid-base indicators of venous and arterial blood in monitoring the condition of horses with recurrent airway obstruction. Prior to treatment involving bronchodilating glucocorticoids, expectorant and mucolytic drugs, more pronounced changes were observed in venous blood (pH 7.283, pCO2 61.92 mmHg, pO2 ...
Perez-Ecija A, Mendoza FJ, Estepa JC, Bautista MJ, Pérez J.A 2-month-old foal with septic shock and severe respiratory distress was referred to the Veterinary Teaching Hospital. Due to poor prognosis, the foal was euthanized. Histopathology showed lesions suggestive of Rhodococcus equi infection associated with a diffuse interstitial infiltrate of foamy macrophages and syncytial cells presenting large acidophilic intranuclear inclusion bodies, fibrin exudates and hyaline membranes. Bacteriological examination from lung and respiratory exudates confirmed R. equi infection, whilst immunohistochemistry and PCR yielded a positive result for Equid herpesvi...
Orsini JA, Baird DK, Ruggles AJ.A 7-year-old female Thoroughbred was admitted with a history of labored breathing, stridor, and exercise intolerance. Examination revealed a mass in the left paranasal sinuses that was determined to be an ossifying fibroma. Initial treatment consisted of surgical removal of the mass alone; however, the mass recurred 9 months after surgery. The mass was again removed, and adjunctive radiotherapy consisting of 3,000 cGy of cobalt radiation was administered. This time, the tumor did not recur for > 6 years. A third surgery was performed to remove the mass, and adjunctive radiotherapy consisting o...
Lane JG, Longstaffe JA, Gibbs C.The clinical and radiographic features of 15 cases of paranasal sinus cysts are described. Breed, sex and side frequency were unremarkable but two distinct categories of age incidence emerged. Onset of signs had occurred before one year of age in three cases, while all but two of the remaining 12 animals were older than nine years. The most common clinical signs were nasal airway obstruction, facial swelling and nasal discharge, often occurring in combination. Radiographic changes were recorded in all horses. Sinus opacification was a consistent finding and in several cases the bone surroundin...
Cuvelliez SG, Eicker SW, McLauchlan C, Brunson DB.Anesthesia of equids is associated with pulmonary dysfunction. Cardiovascular and respiratory effects of inhalation anesthetic agents and duration of anesthesia have been studied, using oxygen as the carrier gas. To our knowledge, the effects of inspired oxygen have not been determined. We studied the cardiovascular and respiratory effects of 2 inspired oxygen fractions (0.30 and greater than 0.85) in 5 laterally recumbent, halothane-anesthetized horses. Mean systemic arterial blood pressure, cardiac output, central venous pressure, pulmonary arterial pressure, arterial pH, and arterial base e...
Busija DW, Orr JA, Rankin JH, Liang HK, Wagerle LC.The effect of hyperoxia on cerebral blood flow (CBF) was examined in 12 unanesthetized ponies. CBF was determined using radioactive microspheres, 15 micrometer in diam, durijng inspriation of the following gases: 1) room air (control); 2) 40% I2 in N2; and 3) approximately 100% O2 with 2.2-4.5% CO2 added to maintain isocapnia. CBF did not change from control values during either level of hyperoxia. However, cerebrospinal fluid (CSF) carbon dioxide tension (PCO2) increased during 40% O2 (delta 1.0 Torr) and approximately 100% O2 (delta 2.9 Torr). This rise in CSF PCO2, not due to a change in CB...
McGilvray TA, Cardwell JM.Exercise induced pulmonary haemorrhage (EIPH) is an important condition of horses performing high intensity exercise, with reported prevalence among racehorses of up to 95%, based on the detection of blood on tracheobronchoscopy. Previously identified risk factors include age, sex, season, race type, years spent in racing and lower airway inflammation. Objective: To estimate the prevalence of EIPH in British National Hunt racehorses as indicated by two outcome measures: presence of tracheal blood on tracheobronchoscopy, and presence of moderate-large (significant) proportions of haemosideropha...
Zarski LM, Vaala WE, Barnett DC, Bain FT, Soboll Hussey G.Equine herpesvirus 1 (EHV-1) ubiquitously infects horses worldwide and causes respiratory disease, abortion, and equine herpesvirus myeloencephalopathy. Protection against EHV-1 disease is elusive due to establishment of latency and immune-modulatory features of the virus. These include the modulation of interferons, cytokines, chemokines, antigen presentation, and cellular immunity. Because the modulation of immunity likely occurs at the site of first infection-the respiratory epithelium, we hypothesized that the mucosal influenza vaccine Flu Avert I.N. (Flu Avert), which is known to stimulat...
Muir WW, Skarda RT, Sheehan WC.The cardiopulmonary effects of two xylazine-morphine sulfate drug combinations (mixtures) given IV were evaluated in horses. In horses given xylazine (0.66 mg/kg of body weight) and morphine sulfate (0.12 mg/kv) IV (experiment 1), there were significant (P less than 0.05) decreases in heart rate, cardiac output, and respiratory rate. Central venous pressure was significantly (P less than 0.05) increased. Arterial and pulmonary arterial blood pressures increased significantly (P less than 0.05) but transiently. Arterial blood gas tensions (PaCO2 and PaO2) and pH remained unchanged. In the horse...
