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.
Barnes GR, Brennan M, Goulden BE, Kirkland J.One problem in the diagnosis of subclinical roarers is that abnormal auditory signals occur only during a fast gait, and these fade quickly. This paper offers a novel technique to assist this problem. Sound recordings were obtained from five horses following exercise; two roarers, two non-roarers, and one suspected roarer. These signals were converted into spectrograms by Rayspan processing. All frequencies in the 0 to 2.25 kHz range during both inspiration and expiration, as well as occasional noises in the 2–4 kHz band, characterised roarers. Signals from non-roarers consisted of frequenci...
McPherson EA, Lawson GH, Murphy JR, Nicholson JM, Breeze RG, Pirie HM.Micropolyspora faeni and Aspergillus fumigatus were identified as common causes of respiratory hypersensitivity in horses affected with chronic obstructive pulmonary disease (COPD). Rye grass pollen and an Actinomycete evoked respiratory allergy in a few horses. Not infrequently, individual horses were found to have respiratory hypersensitivity to two or more antigens. The methods used to examine for allergy were intradermal testing and inhalation challenge with environmental antigens. An intradermal test using an M faeni extract was demonstrated to be suitable for diagnostic use in horses pre...
Heffron CJ, Baker GJ.Fibreoptic endoscopy was used to study the movements of the larynx and pharynx during nasal occlusion in 10 horses, which showed signs consistent with functional pharyngeal obstruction (FPO) on exercise. Cine-endoscopic films were made on 3 such horses. Consideration of the anatomy of the region indicates that FPO may best be regarded as a subluxation of the nasopharyngeal and larygneal airways and it was found that a constant component of the movements which brought about this subluxation was a marked caudal retraction of the larynx. It is suggested that this caudal retraction of the larynx o...
Stanek KA, Nagle FJ, Bisgard GE, Byrnes WC.Published reports of oxygen consumption (VO2) during exercise in hyperoxia are equivocal. By and large, when measured at the lung using respiratory gas equations, VO2 is elevated in hyperoxia and, when measured at the blood-tissue level using the cardiovascular Fick (CVF) equation, it is unchanged. We sought to provide some insight into this problem by making through the use of both equations simultaneous determinations of VO2 during hyperoxia in exercising ponies. In normoxia, during treadmill exercise (115 m/min, 10% grade) of seven ponies, there was no difference in exercise VO2, whether it...
Willoughby RA, McDonell WN.Pulmonary function tests in horses are in the early stages of development and there will be a limit in the range of tests available since those requiring patient cooperation cannot be conducted in animals. Some tests such as blood gas analysis, A-aDo2 and delta Ppl measurements could presently be used to a greater extent under field conditions. Others that require expensive equipment and considerable technical assistance will be limited to the larger referral type veterinary clinics until the time is reached when there is adequate information to select those procedures that give a reasonable c...
Hall LW.Catheters were implanted through the left atrium into large veins drawing blood from regions of the diaphragmatic lobes in five ponies. Measurement of oxygen and carbon dioxide tensions in blood samples drawn through these catheters showed that in laterally recumbent conscious and anaesthetised animals the function of the lowermost lung is progressively impaired while in the supine position the function of both lungs is adversely affected.
McDonell WN, Hall LW, Jeffcott LB.Studies in conscious and anaesthetised ponies demonstrated that starvation, anaesthesia and changes in body position influence the radiographic appearance of the lungs in the lateral and dorsoventral views. Radiographic appearances could not be closely correlated with blood gas values, but they suggested that the volume of the lowermost lung of the laterally recumbent animal is greatly reduced.
Valdez H, McMullan WC, Hobson HP, Hanselka DV.A 6-month-old Appaloosa colt had a deviation of the premaxilla and nasal septum as well as a dorsal hump of the nasal bone and maxillomandibular malocclusion. Two surgical procedures were performed 12 weeks apart to correct these anomalies. An intraoral approach and autogenous rib graft were used to correct the malocclusion and deviation of the premaxilla. Osteotomy of the nasal bone and removal of the nasal septum were performed to help correct the deviation and to facilitate free air passage through the nares.
Attenburrow DP.A graphic representation is presented of respiratory sounds recorded by a radio-stethoscope from normal horses exercised at the walk, trot, canter and gallop. Methods whereby inspiratory and expiratory sounds were distinguished are discussed. The form of amplitude envelopes of the sounds recorded at different gaits are compared. Certain measurements of relative amplitudes and the form of amplitude envelopes of the recorded respiratory sounds can be recognised as typical of normal horses when exercised at the canter and gallop. The influence of some physiological events (e.g. deglutition on the...
Murphy JR, Breeze RG, McPherson EA.Bronchial myxoma occurred in an aged Arab mare with longstanding respiratory disease wrongly attributed to chronic obstructive pulmonary disease. Blood gas and maximum intrathoracic pressure change measurements were not consistent with this latter diagnosis, and this was supported by aerosol antigen provocation tests. Radiography demonstrated a hilar mass in the thorax, and this proved to be a myxoma at necropsy.
Bisgard GE, Forster HV, Byrnes B, Stanek K, Klein J, Manohar M.Ventilation, metabolism, arterial blood gases, and blood and cerebrospinal fluid (CSF) acid-base status were measured in exercise studies on seven ponies during mild, moderate, and near-maximal treadmill exercise. CSF and arterial blood were sampled via indwelling catheters. Generally measurements were made during the 3rd, 6th, and 9th minute of steady-state exercise, with CSF sampled only during the 9th minute. Alveolar ventilation (VA) and metabolic rate (VO2) increased proportionately during exercise below the anaerobic threshold, but above this threshold, VA increased at a faster rate than...
Steffey EP, Howland D.The minimal alveolar concentration (MAC) of halothane which just prevented purposeful movement in response to electrical stimulation was determined in 11 young, healthy, unpremedicated horses breathing oxygen (O2) or nitrous oxide (N2O) and O2. Ventilation was controlled during these MAC studies. The arterial PO2 was always greater than 90 mm of Hg and the average PaCO2. range was 36 to 40 mm of Hg. The MAC for halothane in O2 was 0.93 vol %. Alveolar N2O concentrations of 25% and 50% reduced the halothane MAC about 12% and 25%, respectively. In 8 of these horses, the cardiovascular effects of...
Roberts MC, Groenendyk S, Kelly WR.A 4 month old foal with right sided maxillary enlargement and considerable upper airway obstruction had an ameloblastic odontoma in the right maxillary sinus. This odontogenic tumour, probably congenital in nature, had extensively distorted the structure and contours of the sinus, and displaced the adjacent turbinates and nasal septum.
Chand N, Eyre P.Histamine, 2-methylhistamine (a specific H1-agonist), 5-HT, PGF2alpha, SRS-A, bradykinin (BK) and carbachol contract bronchial and tracheal smooth muscles of the horse. Isoprenaline, PGE1, E2, dimaprit and 4-methylhistamine (last two = specific H2-agonists) relaxed airways which were partially contracted to carbachol. Mepyramine (a specific H1-antagonist) selectively antagonized contractions to histamine. In the presence of mepyramine, histamine caused relaxation of airways partially contracted to carbachol. Metiamide and burimamide (specific H2-antagonists) specifically antagonized or reverse...
Dixon RJ, Hartley WJ, Hutchins DR, Lepherd EE, Feilen C, Jones RF, Love DN, Sabine M, Wells AL.An outbreak of perinatal foal mortality associated with a herpesvirus is described. Twenty two foals either were still-born, or died soon after birth, or were weak and soon developed severe respiratory signs, or were normal at birth and developed respiratory symptoms 18 to 24 hours later. Elevated temperatures, heart and respiratory rates were constant features. The animals were severely leucopaenic, and showed an absolute neutropaenia. At autopsy the lungs were enlarged, and showed varying degrees of aeration and moderate to severe oedema and congestion. Histopathology showed an acute focal n...
Forster HV, Bisgard GE, Dempsey JA, Orr JA.Numerous studies have demonstrated the existence of an intracranial [H+] chemoreceptor mechanism capable of stimulating ventilation. 1 Supposedly, this chemoreceptor is located 0.2 mm below the surface of the ventrolateral side of the medulla and is responsive to [H+] in the surrounding cerebral extracellular fluid (ECF). During chronic conditions, ECF [H+] is supposedly in equilibrium with CSF [H+]; hence, stimulus level can be established through sampling and analysis of CSF. In this presentation, we summarize data from studies on spontaneously breathing, unanesthetized ponies which suggests...
Powers SK, Beadle RE, Thompson D, Lawler J.The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work rates: 50 m/min 6% grade and 70 m/min 12% grade. PaCO2 decreased (P less than 0.05) below resting values within 1 min after commencement of exercise at both work rates and reached a nadir at 90 s. PaCO2 decreased maximally by 2.5 and 3.5 Torr at the low and moderate rate, respectively. Aft...
Moghtaderi M, Farjadian S, Hosseini Z, Raayat A.The aim of this study has been to investigate the frequency of sensitization to horse allergens and clinical symptoms in horse riders. Methods: A total of 42 horse riders and 50 healthy individuals were examined by means of skin prick tests for a panel of horse and common animal allergens, and pulmonary function tests were done by spirometry. Results: The rate of sensitization to horse allergens was 31% as proven by the skin prick test in horse riders whereas horse sensitization was not seen in the control group. Occupational allergy symptoms were reported by 19 horse riders. Two horse riders ...
Tulleners EP, Harrison IW, Raker CW.By use of endoscopy, 75 horses with respiratory noise and/or exercise intolerance were determined to have structural arytenoid cartilage abnormalities (60 primary, 11 after previous laryngeal surgery), or failed left laryngoplasty (4 horses) for laryngeal hemiplegia in which the arytenoid cartilage still appeared normal. Eighty-eight percent of the horses were either Thoroughbred (54 horses; 72%) or Standardbred (12 horses; 16%) racehorses; only 9 horses (12%) had occupations not related to racing. Seventy-six percent of the racehorses were 2 to 4 years old; all non-racehorses were greater tha...
Jean D, Lavoie JP, Nunez L, Lagacé A, Laverty S.A 6-year-old Thoroughbred mare had a 7-cm ulcerated mass on the cranial aspect of the left cervical area. Ultrasonography revealed the mass to be < 1 cm thick and composed of small lobules that were filled by material hypoechoic to the surrounding muscle tissues. Fine-needle aspiration of the mass yielded blood, and cytologic examination revealed a few epithelial cells with neoplastic changes. Thoracic radiography revealed an interstitial pattern with several disseminated nodules. A diagnosis of cutaneous hemangiosarcoma with pulmonary metastases was made. The diagnosis was confirmed at necrop...
Shappell KK, Stick JA, Derksen FJ, Scott EA.Between 1981 and 1986, permanent tracheostomy was performed in 46 ponies and 1 adult Quarter Horse. Tracheostomies of 19 ponies and the horse were examined in June 1986 and evaluated for vertical length of stomal orifice (mean = 25.0 +/- 4.7 mm in the ponies and 55 mm in the horse), degree of tracheal obstruction (0/20), regrowth and apposition of epidermis (3/20), and whether or not stomal airflow occurred with nasal occlusion (20/20). In addition, the animals were evaluated to determine whether dyspnea developed during exercise. Records of 27 ponies were evaluated. Six of the 27 were not dys...
Luna SP, Taylor PM.Halothane depresses cardiorespiratory function and activates the pituitary-adrenal axis, increasing beta endorphin. In horses, beta endorphin may enhance the anaesthetic-associated cardiorespiratory depression and mortality risk. The authors studied endogenous opioid effects on cardiorespiratory function and pituitary-adrenal activity in halothane-anaesthetised ponies by investigating opioid antagonism by naloxone. Six ponies were anaesthetised three times (crossover design). Anaesthesia was induced with thiopentone and maintained with 1.2 per cent halothane for 2 hours. Immediately after indu...
Tulleners E.Transendoscopic laser surgery provides equine surgeons with a safe, reliable, and minimally invasive method of performing many surgical procedures in the upper respiratory tract. Although the Nd:YAG laser has proven efficacy, other newer lasers such as the diode and holmium: YAG lasers may prove to be useful tools for equine upper respiratory tract surgery. Long grasping forceps and a high quality fiberoptic or video endoscope are critical components necessary for performing transendoscopic laser surgery. For many of the most common upper respiratory tract abnormalities, a laryngotomy can be e...
Hoffman AM, Viel L, Prescott JF.Despite the high incidence of distal respiratory tract infection of undetermined cause on farms, to our knowledge, the microbiologic effects of conventional antimicrobial treatment for this condition have not been studied. We evaluated the possible pathogenic role of bacterial isolates from the distal airways of foals with clinical respiratory tract disease, by correlating changes in their numbers (increase or decrease) with clinical, endoscopic, and pulmonary cytologic signs of disease resolution during treatment with antimicrobial drugs. We also determined qualitative changes in in vitro ant...
Dacre KJ, McAleese SM, Knight P, McGorum BC, Pemberton AD.Mast cell mediators are believed to play a central role in inflammatory lung disorders such as human allergic and occupational asthma. Equine heaves is characterized by reversible neutrophilic airway inflammation and airway obstruction, primarily due to bronchospasm and mucus hypersecretion, following exposure of susceptible horses to organic stable dusts. As such, heaves shares many similarities with human occupational dust-induced asthma and therefore it is proposed that mast cells may also be implicated in the pathogenesis of heaves. Tryptase, a mast cell-specific proteinase, can be used as...
Marlin DJ, Young LE, McMurphy R, Walsh K, Dixon P.There is evidence that halothane inhibits nitric oxide synthase in vitro, but the effect of intravenous anaesthetic agents is less clear. This study was undertaken to compare the rate of exhaled nitric oxide production (VNO) in spontaneously breathing horses anaesthetized with halothane or an intravenous regimen. Seven adult horses were studied twice in random order. After premedication with romifidine 100 microg kg(-1), anaesthesia was induced with ketamine 2.2 mg kg(-1) and maintained with halothane in oxygen (HA) or by an intravenous infusion of ketamine, guaiphenesin and romifidine (IV). I...
Hummer EV, Soares JHN, Crockett DC, Aguiar AJA, Tran MC, Cronin JN, Brosnan RJ, Braun C, Formenti F.The possibility of accurately and continuously measuring arterial oxygen partial pressure (PaO2 ) in horses may facilitate the management of hypoxaemia during general anaesthesia. Objective: The aim of this study was to evaluate the ability of a novel fibreoptic sensor to measure PaO2 (PaO2Sensor ) continuously and in real time in horses undergoing ventilatory manoeuvres during general anaesthesia. Methods: In vivo experimental study. Methods: Six adult healthy horses were anaesthetised and mechanically ventilated in dorsal recumbency. A fibreoptic sensor was placed in one of the facial arteri...
Cabler P, Geddes LA, Rosborough J.Ultrasonic energy, provided by a commercially available water vaporizer, was used to vaporize methoxyflurane, halothane, and chloroform. The vaporizer was placed directly in the respiratory line, and the anaesthetic liquid was vaporized one drop at a time. Anaesthesia was maintained for periods up to 6 hr in horses, ponies, calves, sheep, dogs, and one pig. This method of vaporizing liquids is applicable to a wide variety of anaesthetics. It is easily controlled, and the same vaporizer can be used with a wide range of sizes of subjects. The vaporizer can be placed directly in the respiratory c...
Mair TS, Stokes CR, Bourne FJ.The immunoglobulin (Ig) content of serum and tracheal lavage fluid was measured in 50 horses suffering from chronic obstructive pulmonary disease (COPD) and 40 control horses. The mean immunoglobulin: albumin ratios of the lavage fluids of both groups were significantly higher than the corresponding values for serum, which indicates significant local production of immunoglobulins in the lower respiratory tract. The IgA: albumin ratio of lavage fluid was significantly higher in diseased compared with normal horses, which implies increased local production of IgA in this disease. The IgG: albumi...
Foreman JH.Differentiation of diseases of the equine respiratory tract is based on history, clinical signs, auscultation, endoscopy, imaging, and sampling of airway exudate. Upper respiratory therapies include surgical correction of airway obstructions; flushing of localized abscesses (strangles), guttural pouch disease, or sinusitis; and oral or parenteral antibiotic and anti-inflammatory therapy if deemed necessary. Pneumonia usually is treated with antimicrobials, anti-inflammatories, and bronchodilators. Pleural drainage is indicated if significant pleural effusion is present. The most commonly used ...
Tobin T, Swerczek TW, Blake JW.This report concerns the detection and acute toxicity of pine oil (a commercially available disinfectant) after intravenous administration in horses. alpha Terpineol was identified as a major constituent of pine oil. alpha Terpineol was recovered from equine tissues by extraction into heptane and detected by gas chromatography, using either flame ionization detection or pentafluoropropionic anhydride derivatization and electron capture detection. After intravenous injection of 0.1 ml/kg, death due to massive pulmonary edema occurred within minutes. In this animal blood and tissue levels of alp...
Greene HM, Hurson MJ, Wickler SJ.Despite the common use of equids as visitors to high altitude mountainous environments, there are a paucity of carefully orchestrated scientific approaches. Further, again as a function of a common perceived advantage of mules over horses in these similar environments there are needs for controlled comparisons between these 2 equids. Objective: To measure haematological and respiratory function in horses and mules at low altitude (225 m), at rest and post exercise. In addition the rate and magnitude of these changes were followed over a 13 day period at high altitude (3800 m) to contrast accli...
Manohar M, Duren SE, Sikkes B, Day J, Baker JP.Distribution of blood flow among various respiratory muscles was examined in 8 healthy ponies during submaximal exercise lasting 30 minutes, using radionuclide labeled 15-microns diameter microspheres injected into the left ventricle. From the resting values (40 +/- 2 beats/min; 37.3 +/- 0.2 C), heart rate and pulmonary arterial blood temperature increased significantly at 5 (152 +/- 8 beats/min; 38.6 +/- 0.2 C), 15 (169 +/- 6 beats/min; 39.8 +/- 0.2 C), and 26 (186 +/- 8 beats/min; 40.8 +/- 0.2 C) minutes of exertion, and the ponies sweated profusely. Mean aortic pressure also increased progr...
Kozlov SA.The results of applying N. N. Sirotinin's concept of the use of hypoxic adaptation to enhance working capacity are given. There is evidence for the efficiency of adaptation of trotters to two hypoxias: to hypoxic hypoxia (in the midmountains) and to exercise hypoxia (during interval training under the conditions of Moscow) for increasing their performance. These studies demonstrated that in the midmountains, the trotters had more infrequent respiration, increased respiratory and minute respiratory volumes which were more obvious by the end of a monthly mountain stay. The monthly training of tr...
Lakritz J, Wisner ER, Finucane T, O'Brien TR, Tyler WS, Pascoe JR, Plopper CG.Interstitial and bronchointerstitial pulmonary patterns are commonly observed in thoracic radiographs of Thoroughbreds. Prominent interstitial and bronchointerstitial pulmonary patterns are observed in clinically normal horses, and in horses with respiratory tract disease. Until recently, the relevance of these pulmonary patterns was not known. Previous studies indicated that bronchiolitis, bronchiolar epithelial hyperplasia, epithelial metaplasia, and bronchial arteriolar recruitment correlated strongly with the prominence of the interstitial and bronchointerstitial pulmonary patterns observe...
Ratajczak K, Kiełbowicz Z.Prolonged operation or a current need to improve intraoperative conditions, while anaesthesia is still on, may require applying controlled ventilation (CV). The purpose of this study was to evaluate cardiovascular effects of such a decision. Seven halothane-anaesthetized horses were the subject of our investigation, at first kept spontaneous ventilation (SV), then they were connected to respirator. After 30' CV, SV was restored and anaesthesia was continued. In those three stages of experiment haemodynamic parameters and gasometry were measured. It was found that during CV period both optimal ...
Pringle J, MacMillan K, Briand H, Stämpfli H.The heart rate changes during routine training in a group of 8 actively racing Standardbreds were used to simulate the training work on a treadmill (ST) and indices of exercise compared to maximal effort (MAX) on the treadmill. The following parameters were recorded during treadmill work: heart rate, velocity, O2 consumption, respiratory and stride frequency, and stride length. Blood lactate concentrations were measured before and after each work test. Heart rate during simulated training was mean +/- s.d. 87.8 +/- 5.5% heart rate in MAX, one of the 8 horses working 0.05), being higher during...
O'Callaghan MW, Sanderson GN.A method for performing bronchography in standing nonanaesthetized horses was developed. Bronchography was performed by insufflating the previously intubated trachea with a mixture of 120 to 200 g of finely powdered barium sulphate mixed with 3 to 7 g of powdered methyl cellulose. The mixture was delivered from an ether vaporiser into which compressed air was blown. Premedication with atropine sulphate immediately before insufflation minimised bronchoconstriction. Satisfactory bronchograms with contrast visible down to the seventh and eighth bronchial divisions were obtained in 80 per cent of ...
Krpan MK.Transtracheal aspiration is used to obtain samples for culture and cytologic examination of respiratory tract secretions and exudates. A 15-cm-long area of the ventral midcervical region is surgically prepared, a small site infiltrated SC with 2-3 ml lidocaine, and a stab incision made in the skin. A trocar with cannula is inserted through the incision and annular ligament into the trachea and the trocar removed. An 8-Fr polypropylene catheter is inserted about 35-40 cm down the trachea and attached to a 30-ml syringe, containing 20 ml sterile saline, with a 3-way stopcock . The saline is rapi...
Orr JA, Erichsen DF, Shirer HW, Allen PL, Payne PA.The aim of this study was to determine whether increases in ventilation would occur during intravenous acid infusion even if systemic arterial pH was held constant. In six awake ponies, HCl (500 ml, approximately 0.312 M) was infused into the right atrium at a total dose of 1.0 meq/kg over 18 min while an equivalent dose of NaOH was infused into the left heart to restore systemic arterial pH to normal. Total ventilation increased at the onset of the infusion and remained elevated although systemic arterial pH was normal to slightly alkaline. The increase in ventilation during the initial 2 min...
Ehrlich PJ, Seeherman HJ, Morris E, Kolias C, Cook WR.The effect of left recurrent laryngeal neuropathy (LRLN) on the metabolic cost of locomotion (MCL) and peak aerobic power (VO2peak) was evaluated in four trained Thoroughbred racehorses. Oxygen consumption (VO2), carbon dioxide production (VCO2), venous lactate concentrations (LAC), and heart rate (HR) were measured during a treadmill exercise test (TET). Each horse performed the exercise test four times, alternating between normal upper airway function and reversibly induced LRLN. Subcutaneous infusion of 2% mepivicaine, a local anesthetic, into the region were the left recurrent laryngeal ne...
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)...
Russold E, Ambrisko TD, Schramel JP, Auer U, Van Den Hoven R, Moens YP.To compare tidal volume estimations obtained from Respiratory Ultrasonic Plethysmography (RUP) with simultaneous spirometric measurements in anaesthetized, mechanically ventilated horses. Methods: Prospective randomized experimental study. Methods: Five experimental horses. Methods: Five horses were anaesthetized twice (1 week apart) in random order in lateral and in dorsal recumbency. Nine ventilation modes (treatments) were scheduled in random order (each lasting 4 minutes) applying combinations of different tidal volumes (8, 10, 12 mL kg(-1)) and positive end-expiratory pressures (PEEP) (0,...
Koterba AM, Wozniak JA, Kosch PC.This study investigated the developmental changes in the mechanical properties of the respiratory system in growing horses. Pulmonary mechanics and lung volumes were serially measured in anesthetized foals during the first year of life. Quasi-static pressure-volume curves were generated, and functional residual capacity (FRC) was measured using a closed nitrogen equilibration technique. At birth, chest wall compliance normalized to body weight was substantially less than that reported in other less precocious newborn species, while lung compliance normalized to body weight was similar to value...
Kirschvink N, Art T, Lekeux P, Roberts C, Gustin P.8-Epi-PGF2alpha, a prostaglandin-like compound generated by oxidative stress, has been shown to be an in vitro bronchoconstrictor in airways from healthy laboratory animals and healthy humans, but it has never been studied in diseased airways. Here, the bronchoconstrictive capacity of 8-epi-PGF2alpha on isolated bronchial rings (BR) of healthy and heaves-affected horses was evaluated by comparing the maximal effect and the potency of 8-epi-PGF2alpha to those of (1) acetylcholine (ACh), (2) its stereoisomer PGF2alpha and (3) its synthetic receptor agonist, U46619. Furthermore, the potential cap...
Sonea IM, Bowker RM, Robinson NE, Holland RE.The lungs of neonatal foals contain many nerves immunoreactive for substance P and calcitonin gene-related peptide. These nerves are closely associated with the epithelium, bronchial and pulmonary vessels and the airway smooth muscle of all intrathoracic airways, including non-cartilaginous bronchioles. Activation of sensory nerves in the respiratory epithelium could thus potentially affect, via local axon reflexes, vascular and respiratory smooth muscle in neonatal equine airways. Nerves immunoreactive for these peptides are much more widely distributed within the lung than in adult horses; t...
