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.
Cordeau ME, Joubert P, Dewachi O, Hamid Q, Lavoie JP.Heaves is a common condition of horses of cold climate that is characterized by small airway inflammation and obstruction following exposure of susceptible horses to moldy hay and straw. It has been shown that helper T lymphocytes (Th) orchestrate the inflammatory response in asthma and in various animal models of allergic lung diseases by the release of Th2-type cytokines. Results of previous studies indicate that a predominant expression of Th2-type response by airway cells may also be present in heaves. To evaluate the temporal mRNA expression of Th1 (IFN-gamma) and Th2 (IL-4, IL-5) type cy...
Chaffin MK, Cohen ND, Martens RJ, Edwards RF, Nevill M.To identify foal-related risk factors associated with development of Rhodococcus equi pneumonia among foals on farms with endemic R. equi infection. Methods: Prospective case-control study. Methods: 220 foals at 2 equine breeding farms in Texas during a 2-year period. Methods: Information collected for each dam included age, time housed on the farm prior to parturition, whether there were any peripartum illnesses, parity, and health of previous foals. Information collected for each foal included breed, sex, gestational age, month and year of birth, location of birth, type of flooring and beddi...
Manohar M, Goetz TE, Hassan AS.The objective of the present study was to examine the effects of preexercise NaHCO(3) administration to induce metabolic alkalosis on the arterial oxygenation in racehorses performing maximal exercise. Two sets of experiments, intravenous physiological saline and NaHCO(3) (250 mg/kg i.v.), were carried out on 13 healthy, sound Thoroughbred horses in random order, 7 days apart. Blood-gas variables were examined at rest and during incremental exercise, leading to 120 s of galloping at 14 m/s on a 3.5% uphill grade, which elicited maximal heart rate and induced pulmonary hemorrhage in all horses ...
Couëtil LL, Ward MP.To identify risk factors for recurrent airway obstruction (RAO) among horses examined at veterinary teaching hospitals in North America. Methods: Retrospective case-control study. Methods: 1,444 horses with RAO and 1,444 control horses examined for other reasons. Methods: The Veterinary Medical Database was searched for records of horses in which RAO was diagnosed. A control group was identified by randomly selecting a horse with a diagnosis other than RAO that matched the institution and year of admission for each of the horses with RAO. Information obtained included hospital, admission year ...
McCue ME, Davis EG, Rush BR, Cox JH, Wilkerson MJ.A 4-year-old Paint mare was examined because of respiratory tract infection, dermatitis, and weight loss of 2 months' duration. Initial examination revealed generalized pruritic dermatitis, ocular and nasal discharges, and stranguria. Laboratory abnormalities included leukopenia and hypoalbuminemia. Further examination of the respiratory tract revealed grade III of IV pharyngitis and pyogranulomatous pneumonia. Endoscopic examination of the bladder revealed a prolific mass at the junction of the bladder and urethra. Hypoproteinemia was suspected to be caused by protein-losing enteropathy. On h...
van Erck E, Votion DM, Kirschvink N, Art T, Lekeux P.To compare sensitivity of the impulse oscillometry system (IOS) with that of the conventional reference technique (CRT; ie, esophageal balloon method) for pulmonary function testing in horses. Methods: 10 horses (4 healthy; 6 with recurrent airway obstruction [heaves] in remission). Methods: Healthy horses (group-A horses) and heaves-affected horses (group-B horses) were housed in a controlled environment. At each step of a methacholine bronchoprovocation test, threshold concentration (TC(2SD); results in a 2-fold increase in SD of a value) and sensitivity index (SI) were determined for respir...
Brosnan RJ, Steffey EP, LeCouteur RA, Farver TB, Imai A.To test the hypothesis that isoflurane-anesthetized horses during controlled ventilation and spontaneous ventilation exhibit temporal changes in cerebral hemodynamics, as measured by intracranial pressure and cerebral perfusion pressure, that reflect temporal changes in systemic arterial pressure. Methods: 6 healthy adult horses. Methods: Horses were anesthetized in left lateral recumbency with 1.57% isoflurane in O2 for 5 hours in 2 experiments by use of either controlled ventilation (with normocapnia) or spontaneous ventilation (with hypercapnia) in a randomized crossover design. Intracrania...
Brown JA, Derksen FJ, Stick JA, Hartmann WM, Robinson NE.Show and performance horse with laryngeal hemiplegia (LH) often present for excessive respiratory noise rather than significant exercise intolerance. Therefore, the goal of surgery in these horses is to reduce respiratory noise but there are no quantitative studies evaluating the effect of any upper-airway surgery in LH-affected horses. Objective: To determine whether bilateral ventriculocordectomy (VC) reduces respiratory noise in exercising horses with laryngeal hemiplegia. Methods: Six Standardbred horses with normal upper airways were used in this study. Respiratory sounds and inspiratory ...
Bakos Z, Vörös K, Kellokoski H, Reiczigel J.The aim of the study was to evaluate the diagnostic value of thoracic percussion and ultrasonography with the help of distance measurements and statistical methods in the determination of the caudal lung border in horses with recurrent airway obstruction (RAO). Examinations were performed on 11 healthy, warm-blooded horses of different breeds, age and grade of disease. First, the caudal lung border was determined by the traditional indirect percussion method in the 10th, 12th, 14th and 16th intercostal spaces at the end of inspiration and expiration on both sides of the thorax. To apply standa...
Kindig CA, Ramsel C, McDonough P, Poole DC, Erickson HH.Capillary stress failure-induced (exercise-induced) pulmonary haemorrhage (EIPH) during intense running in horses is thought to involve both intravascular (i.e. mean pulmonary arterial pressure [Ppa] > 100 mmHg) and extravascular (e.g. negative inspiratory pressure swings) mechanisms. Objective: That inclined running would reduce breathing frequency (coupled to stride frequency) and increase tidal volume thus increasing lung volume changes and intrapleural pressure swings resulting in more pronounced EIPH. Methods: Six Thoroughbred horses were run to volitional fatigue (incremental step tes...
Wilson DV, Rondenay Y, Shance PU.To characterize the acute cardiopulmonary effects of severe hemorrhage in anesthetized horses. Methods: Prospective experimental study. Methods: Three geldings and six mares, aged 14.4 +/- 2.7 years, weighing 486 +/- 41 kg (range: 425-550 kg). Methods: Horses were anesthetized using xylazine, guaifenesin, ketamine and halothane or isoflurane. Cardiovascular variables, hematocrit, total solids, capillary refill time (CRT) and color of mucous membranes were measured as blood was collected from the carotid artery into sterile plastic bags. Arterial blood gas analysis was also performed. Results: ...
Skarda RT, Muir WW.To determine the analgesic, behavioral, hemodynamic and respiratory effects of midsacral subarachnoid administration of ropivacaine hydrochloride solution in mares. Methods: Randomized, blinded study. Methods: Ten healthy mares, weighing from 470 to 560 kg. Methods: Intravascular and subarachnoid catheters were placed after infiltration of the skin and subcutaneous tissues with 2% lidocaine. Ropivacaine (0.2%, 5 mL) or 0.9% NaCl was then administered subarachnoidally at the midsacral (S2-S3) vertebrae. Analgesia was determined by lack of sensory perception to electrical stimulation (>40 mA)...
Abraham G, Kottke C, Dhein S, Ungemach FR.Although in the respiratory system there is great therapeutic interest in manipulating and understanding the beta-adrenoceptor-G-protein-adenylate cyclase (AC) signal transduction pathway, little is known on segmental differences among lung, bronchus, and trachea with regard to the receptor concentration and interaction to G-proteins and coupling to AC. In this study, patterns of distribution and absolute quantities of beta-adrenoceptor subtypes beta(1) and beta(2) were determined in membranes of equine lung parenchyma, bronchial and tracheal epithelium with the underlying smooth muscle by sat...
Oku K, Yamanaka T, Ashihara N, Kawasaki K, Mizuno Y, Fujinaga T.To evaluate clinical usefulness of xylazine (1.0 mg/kg)-midazolam (20 microg/kg)-propofol (3.0 mg/kg) anesthesia in horses, 6 adult Thoroughbred horses were examined. The quality of induction varied from poor to excellent and 5 out of 6 horses presented myotonus in the front half of the body. However, paddling immediately after induction observed in other reports of equine propofol anesthesia was not observed. Recovery time was 35.3 +/- 9.3 min and the quality of recovery was calm and smooth in all horses. Respiration rate decreased after induction and hypoxemia was observed during lateral rec...
Frias AF, Mársico F, Gómez de Segura IA, Nascimento PR, Nascimento A, Soares JH, Almosny NR.To characterize responses to different doses of propofol in horses pre-medicated with xylazine. Methods: Six adult horses (five females and one male). Methods: Each horse was anaesthetized four times with either ketamine or propofol in random order at 1-week intervals. Horses were pre-medicated with xylazine (1.1 mg kg-1 IV over a minute), and 5 minutes later anaesthesia was induced with either ketamine (2.2 mg kg-1 IV) or propofol (1, 2 and 4 mg kg-1 IV; low, medium and high doses, respectively). Data were collected continuously (electrocardiogram) or after xylazine administration and at 5, 1...
Lafortuna CL, Saibene F, Albertini M, Clement MG.Horses display remarkable aerobic capabilities, attaining during muscular exercise a maximal rate of oxygen consumption about 30-fold higher than the resting value, and 2.5-fold higher than that of other mammals of similar body mass. Under these circumstances an enormous mechanical burden is expected to impinge on the equine respiratory pump and regulatory mechanisms aiming to minimize this load may play an important role in determining the adequacy of the respiratory system to the metabolic requirements. The behaviour of the respiratory system has been investigated in horses at rest and durin...
Koenig J, McDonell W, Valverde A.The objective of this prospective clinical study was to evaluate the accuracy of pulse oximetry and capnography in healthy and compromised horses during general anesthesia with spontaneous and controlled ventilation. Horses anesthetized in a dorsal recumbency position for arthroscopy (n = 20) or colic surgery (n = 16) were instrumented with an earlobe probe from the pulse oximeter positioned on the tip of the tongue and a sample line inserted at the Y-piece for capnography. The horses were allowed to breathe spontaneously (SV) for the first 20 min after induction, and thereafter ventilation wa...
Dixon RM, McGorum BC, Railton DI, Hawe C, Tremaine WH, Dacre K, McCann J.Laryngoplasty (LP) is currently the most common surgical treatment for equine laryngeal paralysis, however, there have been no reports quantifying the degree of retention of arytenoid abduction following LP. Additionally, the complications of LP have been poorly documented. Objective: To record the degree of arytenoid abduction retention following LP and to accurately document all complications of surgery. Methods: A study (1986-1998) of 200 horses of mixed breed and workload, median age 6 years (prospective 136 cases and retrospective 64 cases) undergoing LP (using 2 stainless steel wires) an...
Picandet V, Léguillette R, Lavoie JP.Corticosteroids are currently the most effective drugs for the control of 'heaves' in horses. However, there is limited information concerning the comparative efficacy and tolerability of the various corticosteroids when used for treatment. Objective: To compare the therapeutic and side effects of isoflupredone acetate to those of dexamethasone. Methods: A parallel design to compare the effects of 2 corticosteroids by evaluating lung function, serum cortisol and electrolyte concentrations, response to ACTH stimulation and haematology sequentially during a 14 day control period (no treatment), ...
MacNeill AL, Alleman AR, Franklin RP, Long M, Giguère S, Uhl E, López-Martinez A, Wilkerson M.A 5-year-old Paso-Fino mare was presented for severe respiratory distress. The mare had foaled 2 months prior to presentation. The horse was in poor body condition with a dull hair coat. A mild fever was noted during physical examination and increased bronchovesicular sounds were auscultated. Thoracic radiographs showed an interstitial pattern and an alveolar infiltrate with distinct air bronchograms. Moderate purulent inflammation with increased mucus was observed in tracheal wash fluid, but no infectious agents were identified. A bronchoalveolar lavage (BAL) contained a large amount of mucus...
Ducharme NG, Hackett RP, Woodie JB, Dykes N, Erb HN, Mitchell LM, Soderholm LV.Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced. Objective: That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise. Methods: Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = ...
Franklin SH, Usmar SG, Lane JG, Shuttleworth J, Burn JF.It has long been recognised that the production of abnormal respiratory sounds by horses during exercise is frequently associated with upper airway obstructions. Respiratory acoustic measurements have shown promise in investigation of upper airway disorders in man and, more recently, in horses with experimentally-induced obstructions. Objective: To evaluate sounds from exercising horses with naturally occurring dynamic obstructions of the upper respiratory tract and to compare these with those from normal horses in order to determine whether different obstructions produce characteristic spectr...
Bettschart-Wolfensberger R, Bowen IM, Freeman SL, Weller R, Clarke KW.To search for long-term total i.v. anaesthesia techniques as a potential alternative to inhalation anaesthesia. Objective: To determine cardiopulmonary effects and anaesthesia quality of medetomidine-ketamine anaesthesia induction followed by 4 h of medetomidine-propofol anaesthesia in 6 ponies. Methods: Sedation consisted of 7 microg/kg bwt medetomidine i.v. followed after 10 min by 2 mg/kg bwt i.v. ketamine. Anaesthesia was maintained for 4 h with 3.5 microg/kg bwt/h medetomidine and propofol at minimum infusion dose rates determined by application of supramaximal electrical pain stimuli. Ve...
Kelly G, Lumsden JM, Dunkerly G, Williams T, Hutchins DR.Mucosal ulcers and, occasionally, small granulomas on the axial surface of one or both arytenoid cartilages have been found in TB yearlings presented for post sale endoscopic examination. Objective: To determine the incidence, endoscopic characteristics and outcome of a group of Thoroughbred yearlings affected with mucosal ulcers and granulomas of the arytenoid cartilage. Objective: The incidence of mucosal ulceration of the arytenoid cartilages of yearling Thoroughbreds is relatively high compared to other upper airway abnormalities; and that the majority of mucosal ulcers heal uneventfully, ...
van den Hoven R, Zappe H, Zitterl-Eglseer K, Jugl M, Franz C.The effects of an oral preparation containing an extract of thyme and primula (Bronchipret; Bionorica) on the lung function of five horses suffering heaves were determined in a longitudinal study. The horses accepted the product well. The plasma concentrations of the marker substance, thymol, indicated that at least one of the substances in the extract had been absorbed from the gastrointestinal tract. The compliance, pulmonary pressure and airway resistance of the horses' lungs were all significantly improved after one month of treatment However, the severity of their clinical signs and their...
Wilkins PA.Lower airway problems of the adult horse are commonly encountered by the practitioner. Particularly susceptible populations include horses transported for any significant distance and young horses grouped together for training and/or competition. This article presents some of the commonly encountered problems of this patient population, including bacterial pneumonia/pleuropneumonia and influenza, and some uncommon ones, including pulmonary edema, pneumothorax/hemothorax, and acuterespiratory distress syndrome. Information is presented that should allow the practitioner to diagnose these proble...
Wilkins PA.The newborn foal can experience problems of the lower respiratory tract that are unique to the neonate. The transition to extrauterine life usually occurs rapidly and in a coordinated manner, but problems associated with the peripartum period, including placentitis, dystocia, infection, and trauma, can result in conditions that compromise gas exchange in the newborn foal. This article reviews the normal transition and presents some of the problems seen in these small patients.
Dickinson CE, Traub-Dargatz JL, Dargatz DA, Bennett DG, Knight AP.To determine the clinical manifestations, morbidity, mortality, and treatment methods for rattlesnake venom poisoning in horses. Methods: Retrospective analysis of medical records. Methods: 27 horses with acute venom poisoning attributable to prairie rattlesnakes, and 5 with chronic problems subsequent to a rattlesnake bite. Results: Most horses were bitten on or near the muzzle while on pasture, resulting in head swelling, dyspnea, and epistaxis. Additional manifestations of acute poisoning included fever, tachycardia, tachypnea, cardiac arrhythmia, hemolytic anemia, thrombocytopenia, hemorrh...
Bayly WM, Schultz DA, Hodgson DR, Gollnick PD.Experiments were undertaken to determine whether respiratory masks worn by horses exercising strenuously on a treadmill may interfere with normal gas exchange. Four collection systems, two flow-through systems and two incorporating one-way valve systems with subject-generated airflow were studied. Six horses performed standard treadmill exercise tests consisting of a 2-min warm up followed by galloping 1 min each at 8,9, and 10 m/s. Each horse exercised six times while wearing each of the four respiratory masks. Each flow-through system was used twice with flow rates of 2,360 and 3,840 l/min f...
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....
Abraham G, Shibeshi W, Ungemach FR.Responses and functions of airway epithelial cells are stimulated by β₂-agonists via the β₂-adrenergic receptors (β₂-ARs)-G(s)-protein-cAMP-system, thus, affecting airway inflammation such as in asthma and equine recurrent airway obstruction (RAO). Though horses can be used as large animal model for human asthma, evaluation of the expression and functions of the β-AR system in primary equine airway epithelial cells has not been yet carried out. Thus, for the first time, we determined the β-AR density and subtype distribution by [¹²⁵I]-iodocyanopindolol (ICYP) binding, examined ...
Turk MA, Breeze RG, Gallina AM.The pathologic features of bronchiolitis were studied in horses and ponies from 30 minutes to 27 days after an oral dose of 3-methylindole (3MI). From 30 minutes to 3 hours, lesions were limited to nonciliated bronchiolar epithelial (Clara) cells, which lost apical caps and cytoplasmic granules and had dilated smooth endoplasmic reticulum (SER). At 12 hours, necrotic Clara cells were exfoliated; degeneration and necrosis were evident, in bronchiolar ciliated cells. Rare epithelial cells with hyperplastic SER appeared on the denuded basal lamina at 24 hours. Inflammatory cells, epithelia, fibro...
Lavoie JP, Pascoe JR, Kurpershoek CJ.The effects of 3 commonly used dosages (0.3, 0.5, and 1.1 mg/kg of body weight, IV) of xylazine on ventilatory function were evaluated in 6 Thoroughbred geldings. Altered respiratory patterns developed with all doses of xylazine, and horses had apneic periods lasting 7 to 70 seconds at the 1.1 mg/kg dosage. Respiratory rate, minute volume, and partial pressure of oxygen in arterial blood (PaO2) decreased significantly (P less than 0.001) with time after administration of xylazine, but significant differences were not detected among dosages. After an initial insignificant decrease at 1 minute a...
Palmer SE, McDonough SP, Mohammed HO.Between January 1, 2013 and December 31, 2015, findings of a New York State Gaming Commission-Cornell University postmortem examination program were utilized in a multi-disciplinary mortality review process to review 129 racing fatalities at Thoroughbred racetracks operated by the New York Racing Association (NYRA). Musculoskeletal fractures comprised 79% of the fatalities; cardiopulmonary conditions accounted for 12% of the fatalities. Other causes of death included gastrointestinal (3%), respiratory (5%), and central nervous system (2%) conditions. Fetlock failure represented 50% of the musc...
Fjordbakk CT, Chalmers HJ, Holcombe SJ, Strand E.The pathogenesis of dynamic bilateral laryngeal collapse (DLC) associated with poll flexion is unknown. Diagnosis is dependent upon exercise endoscopy while replicating the flexed head position harness racehorses experience during racing. Objective: To describe the effects of poll flexion on rostrocaudal laryngeal positioning and laryngeal lumen width in resting horses diagnosed with DLC compared to controls, and to establish diagnostic criteria for DLC by use of diagnostic imaging. Methods: Case-control study. Methods: Fifty harness racehorses were prospectively included in the study: 25 case...
Art T, Lekeux P.Pulmonary function measurements during exercise were tested for accuracy and reproducibility in 5 saddle ponies weighing 267 +/- 9 Kg. Airflow (V) and tidal volume (VT) were measured with a Fleisch pneumotachograph mounted on a face mask. The linearity of the response and the symmetry of this device were carefully checked. Pleural pressure changes were measured by pleural puncture (Ppl) and with an esophageal balloon catheter (Pes). The elastance of the esophageal wall and the effect of the position of the esophageal catheter tip on Pes were also investigated. Airflow, VT, Ppl, Pes, mask press...
Reed R, Barletta M, Mitchell K, Hanafi A, Bullington A, Knych H, Quandt J, Ryan C, Giguère S.Describe the pharmacokinetics and pharmacodynamics of intravenous hydromorphone in healthy horses. Methods: Masked, randomized, cross-over, Latin square design. Methods: A group of eight healthy adult horses METHODS: Horses were administered each of four treatments with an 8 day washout. Treatments groups included intravenous hydromorphone 0.02 mg kg (LD), 0.04 mg kg (MD), 0.08 mg kg (HD) and saline (P). Blood samples for hydromorphone analysis were obtained for 24 hours after treatment. Plasma hydromorphone was quantified and pharmacokinetic parameters were determined using non-compartmental ...
Tate LP, Sweeney CL, Bowman KF, Newman HC, Duckett WM.Transendoscopic neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was used to treat 12 standing horses with epiglottic entrapment (EE) or dorsal displacement of the soft palate (DDSP), or both. In four horses, transendoscopic laser staphylectomy was performed. The most common presenting complaints were respiratory stridor, cough, and exercise intolerance. Ten horses with EE healed without epiglottic complications; in one horse, partial adhesion of the aryepiglottic fold to one side of the epiglottis was corrected surgically through a laryngotomy incision. One horse with DDSP had no further sign...
Blunden AS, Hannant D, Livesay G, Mumford JA.Welsh Mountain ponies were inoculated with an isolate of Streptococcus pneumoniae, SPE 1618 (capsular type 3) recovered from the equine respiratory tract: 10 ml of a suspension of 10(8) or 10(9) cfu/ml were instilled intratracheally. Fever was observed after either dose but the greater concentration also produced coughing, ocular and nasal discharge, depression and enlargement of submandibular lymph nodes. Cytological evidence of infection was also observed in tracheal washings during the first week after inoculation and corresponded with isolation of S. pneumoniae from the washes. Morbid anat...
Manohar M.Right atrial, right ventricular, and pulmonary artery pressures, along with change in pleural pressure, were determined with catheter-tipped micromanometers in two groups of ponies at rest, as well as during moderate (trot; heart rate = 180 beats . min-1) and severe (gallop; heart rate = 220 beats . min-1) exercise performed on a treadmill. Group A (n = 8) ponies served as controls, and group B ponies (n = 6) had laryngeal hemiplegia (LH) induced by sectioning the left recurrent laryngeal nerve 20-29 days before the study. It was observed that LH ponies could not gallop for more than 45-90 s. ...
The upper respiratory tract is a frequent cause of exercise intolerance in horses, particularly in racing horses. There are a myriad of laryngeal abnormalities that may restrict airflow at the rima glottidis. Careful endoscopic examination is a crucial part of the examination of any racing horse suffering from poor performance. There has recently been interest in spectrum analysis of respiratory sounds. It has been determined that laryngeal hemiplegia and dorsal displacement of the soft palate have unique sound patterns. Therefore, spectrum analysis of respiratory sounds may prove to be useful...
Manohar M, Goetz TE, Hassan AS, Depuy T, Humphrey S.In view of the suggestion that pulmonary injury-induced release of histamine and/or other chemical mediators from airway inflammatory and mast cells contribute to the exercise-induced arterial hypoxemia (EIAH) in human athletes, we examined the effects of pretreatment with a potent anti-inflammatory agent, dexamethasone, on EIAH and desaturation of hemoglobin in horses. Seven healthy, sound, exercise-trained Thoroughbreds were studied in the control (no medications) experiments, followed in 7 days by intravenous dexamethasone (0.11 mg.kg(-1).day(-1) for 3 consecutive days) studies. Blood-gas m...
Hensel M, Meason-Smith C, Plumlee QD, Myers AN, Coleman MC, Lawhon S, Rodrigues Hoffmann A, Rech RR.Pulmonary mycosis secondary to enterocolitis is an uncommon diagnosis in equine medicine, but is thought to result from mucosal compromise and translocation of enteric fungi. The aetiological agent associated with translocation is often identified based on fungal culture or hyphal features in histological sections. In order to understand better the aetiological agents involved, six horses diagnosed with Salmonella enteritis and concurrent pulmonary mycosis were identified retrospectively through a database search of veterinary teaching hospital records. Samples from these cases were subjected ...
Kelly G, Lumsden JM, Dunkerly G, Williams T, Hutchins DR.Mucosal ulcers and, occasionally, small granulomas on the axial surface of one or both arytenoid cartilages have been found in TB yearlings presented for post sale endoscopic examination. Objective: To determine the incidence, endoscopic characteristics and outcome of a group of Thoroughbred yearlings affected with mucosal ulcers and granulomas of the arytenoid cartilage. Objective: The incidence of mucosal ulceration of the arytenoid cartilages of yearling Thoroughbreds is relatively high compared to other upper airway abnormalities; and that the majority of mucosal ulcers heal uneventfully, ...
Bescoby SR, Davis SA, Sherriff M, Ireland AJ.Routine equine odontoplasty is performed by both Veterinary Surgeons and Equine Dental Technicians. The production of aerosolised particulates from motorised equipment has been well documented in human orthodontics but has yet to be investigated in the veterinary industry. Objective: To assess the size, quantity and composition of particulates produced during routine motorised odontoplasty and to model their deposition in the human respiratory tree. Methods: Analytic observational study. Methods: Fifteen-minute routine motorised odontoplasties were performed on cadaver heads with monitoring eq...
Birks EK, Ohmura H, Jones JH.Measurements of gas exchange while breathing gases of different O concentrations are useful in respiratory and exercise physiology. High bias flows required in flow-through indirect calorimetry systems for large animals like exercising horses necessitate the use of inconveniently large reservoirs of mixed gases for making such measurements and can limit the amount of equilibration time that is adequate for steady-state measurements. We obviated the need to use a pre-mixed reservoir of gas in a semi-open flow-through indirect calorimeter by dynamically mixing gases and verified the theoretical ...
Holcombe SJ, Derksen FJ, Robinson NE.Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. Objective: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. Methods: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. Results...
Pearson W, Charch A, Brewer D, Clarke AF.Recurrent airway obstruction (RAO), known previously as chronic obstructive pulmonary disease (COPD), is a debilitating respiratory condition that significantly contributes to lost training days and illness in racehorses. Herbs are becoming increasingly popular for the prophylaxis or treatment of the clinical signs of RAO despite a paucity of research on efficacy and safety. We evaluated the ability of an herbal composite containing garlic, white horehound, boneset, aniseed, fennel, licorice, thyme, and hyssop to reduce the clinical signs of RAO, hypothesizing that the product would safely red...
Stewart AJ, Salazar T, Waldridge BM, Schumacher J, Welles EG, Hanson RR, Sartin EA, Lenz SD, Holland M, Beard DM.A 7-year-old 509-kg (1,120-lb) Tennessee Walking Horse mare was evaluated because of bilateral mucosanguinous nasal discharge, intermittent right-sided epistaxis, and worsening dyspnea of 9 months' duration. Results: Multiple masses in the nasopharynx were detected via endoscopic and radiographic examinations. Cytologic and histologic examinations of biopsy specimens of 1 mass revealed round yeasts with thick nonstaining capsules and occasional narrow-based budding that resembled cryptococcal organisms. Results: Oral administration of fluconazole and organic ethylenediamine dihydriodide and in...
Peroni JF, Horner NT, Robinson NE, Stick JA.Six normal, healthy horses age 3-10 years underwent left and right thoracoscopic examination using a rigid telescope. A minimum of 30 days was allowed between procedures. Horses were restrained in stocks and sedated with a continuous detomidine infusion. After surgical preparation of the hemithorax elected for surgery, and administration of local or regional anaesthesia of the surgery sites, thoracoscopy was completed during two 15 min pneumothorax periods. During the procedures, the thoracic structures were viewed using a 57 cm, 10 mm diameter, 30 degrees rigid telescope connected to a digita...
Kumar P, Timoney JF, Southgate HH, Sheoran AS.The nasal turbinates of 5 young horses were studied by light and scanning electron-microscopy. Stratified cuboidal epithelium lined the rostral part of the dorsal and ventral nasal turbinates of the vestibular region. The polyangular microvillus cells of this region were separated by linear depressions. The mid and caudal parts of the dorsal and ventral nasal turbinates and the rostral part of the ethmoturbinates were lined by pseudostratified columnar ciliated respiratory epithelium. Numerous cilia with dilated blebs on the ciliated cells concealed adjacent non-ciliated supporting cells and g...
Pan LG, Forster HV, Wurster RD, Murphy CL, Brice AG, Lowry TF.We addressed the role of spinal afferent information in the exercise hyperpnea. Arterial PCO2 (PaCO2) was assessed in 10 normal ponies during low (1.8 mph 7% or 17% grade) or moderate (6 mph 7% grade) treadmill exercise. After control studies, bilateral spinal ablation (SA) of the dorsolateral sulcus and dorsolateral funiculus at L2 was performed in seven ponies. In normal ponies within the first 90 s of exercise, PaCO2 initially decreased 2.7, 4.1, and 5.2 Torr below rest at the three work loads, respectively (P less than 0.05). PaCO2 thereafter increased toward resting levels but remained 1....
Stegmann GF, Littlejohn A.The effect of lateral and dorsal recumbency on cardiopulmonary function in six anaesthetised horses were compared. Cardiac output/kg, stroke volume/kg, alveolar ventilation, venous admixture, pulmonary shunt and blood-gas values were determined. From lateral to dorsal recumbency cardiac output/kg decreased non-significantly. A significant increase in pulmonary shunt occurred. A positive correlation between body mass and pulmonary shunt in dorsal recumbency was found. Alveolar ventilation increased significantly in dorsal recumbency when breathing air compared to oxygen.
Pan LG, Forster HV, Kaminski RP.We assessed in ponies the adequacy of using rectal (Tre) rather than arterial temperature (Tar) under conditions common to ventilatory control experiments, i.e., CO2 breathing, thermal stress, and particularly exercise. We were interested in whether, and to what extent, Tar-Tre differences could lead to errors in arterial blood gas corrections. At control environmental temperatures (Ta) of 5 degrees C in the winter and 21 degrees C in the summer, Tar and Tre (37.1 degrees C) did not differ (P greater than 0.05). Elevating winter or summer Ta by 10-18 degrees C for 2-days or lowering summer Ta ...
Taylor PM, Silver M, Fowden AL.The uterine and umbilical vessels of 12 pregnant ponies were catheterised to study foetal metabolism. The effects of this procedure on maternal and foetal cardiovascular, respiratory, metabolic and adrenocortical activity were monitored during and after surgery. Premedication with acepromazine-butorphanol-detomidine was followed by induction of anaesthesia with detomidine and ketamine and maintenance, using mechanical ventilation, with halothane in oxygen and nitrous oxide. Mean maternal arterial blood pressure was greater than 70 mmHg during anaesthesia and arterial oxygen tension remained ov...
Deane JC, Dagleish MP, Benamou AE, Wolf BT, Marlin D.To evaluate the consistency of partial pressures (P) of arterial oxygen (aO(2)), arterial carbon dioxide (aCO(2)) and pH measurements in equine carotid arterial blood samples taken into syringes made from three different materials and stored at room temperature or placed in iced water for measurement at three different times. Methods: Prospective observational study over 19 days. Methods: Four clinically normal Thoroughbred or Thoroughbred-cross horses (three geldings, one mare, mean age 6.25 years, range 5-7 years). Methods: Identical blood samples were taken on two separate occasions from th...
Ahern BJ, Sole A, de Klerk K, Hogg LR, Vallance SA, Bertin FR, Franklin SH.Upper airway endoscopy of thoroughbred (TB) yearlings is commonly used in an attempt to predict laryngeal function (LF) and its impact on future race performance. The aim of this study was to determine if different grading systems and laryngeal grades were correlated with future performance. Methods: Postsale endoscopic recordings were obtained from an Australian TB yearling sale during a four-year period from 2008 to 2011. Horses were included if they had a diagnostic postsale video endoscopic recording and raced within Australia. Recordings were graded using the Havemeyer system and subseque...
