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.
Natalini CC, Paes SD, Polydoro ADS.The study aim is to compare the effects of epidural administration of two different doses of romifidine combined with morphine in horses. A prospective crossover blinded experimental design was used. Five adult healthy horses two males and three females with a mean body weight of 380 ± 45 Kg (335-425 kg), were studied. Treatments consisted of romifidine 30 μg/kg (R30) or 60 μg/kg (R60) combined with morphine 0.1 mg/kg with a washout interval of 72 hours, administered through an epidural catheter placed at the first intercoccygeal space. Heart rate (HR) and respiratory rate (f), pH, blood ga...
de Wasseige S, Picotte K, Lavoie JP.A study reported low systemic availability of injectable dexamethasone nebulized to healthy horses using the Flexineb mask. When used in horses with severe asthma and a different nebulizer, lack of efficacy and cortisol suppression were observed. Objective: Nebulized dexamethasone is as effective as PO administration for the treatment of severe asthma in horses. Methods: Twelve horses with severe asthma from a research herd. Methods: Randomized clinical trial. Horses were divided into 2 groups and received 5 mg of dexamethasone sodium phosphate by nebulization using a Flexineb mask (NE, n = 6)...
Nemanichvili N, Berends AJ, Wubbolts RW, Gröne A, Rijks JM, de Vries RP, Verheije MH.The trimeric hemagglutinin-esterase fusion protein (HEF) of influenza D virus (IDV) binds 9-O-acetylated sialic acid receptors, which are expressed in various host species. While cattle are the main reservoir for IDV, the viral genome has also been detected in domestic pigs. In addition, antibodies against IDV have been detected in other farm animals such as sheep, goats, and horses, and even in farmers working with IDV positive animals. Viruses belonging to various IDV clades circulate, but little is known about their differences in host and tissue tropism. Here we used recombinantly produced...
Ireland JL, McGowan CM.Research demonstrating insulin's causal role in endocrinopathic laminitis has greatly advanced understanding of equine laminitis. However, the degree to which this knowledge has been translated into clinical practice has not been assessed. This two-part study aimed to investigate veterinary surgeons' current diagnostic approach to laminitis, whether this had changed over time, and the impact of diagnosing an endocrinopathy on laminitis case management and outcome. Two cross-sectional online surveys of equine veterinary surgeons working within the UK were undertaken. The first study population ...
Minamijima Y, Niwa H, Uchida E, Yamamoto K.In the past decade, mass spectrometry has become an important technology for protein identification. Recent developments in mass spectrometry allow a large number of identifications in samples; therefore, mass-spectrometry-based techniques have been applied to the discovery of biomarkers. Here, we conducted a proteomic study to compare the proteomes in sera between healthy Thoroughbreds and Thoroughbreds with respiratory disease associated with transport (RDT). We found that four proteins, apolipoprotein F, lipopolysaccharide binding protein, lysozyme and protein S100-A8, were upregulated, whi...
Leventhal HR, McKenzie HC, Estell K, Council-Troche M, Davis JL.The objective of this study was to determine the pharmacokinetics and tolerability of tulathromycin (Draxxin ; 2.5 mg/kg once) after intramuscular (IM), subcutaneous (SC), and slow intravenous (IV) administration to six adult horses. A three-phase design and 4-week washout period were used. Drug concentrations in blood and bronchoalveolar lavage (BAL) samples were determined by ultra-performance liquid chromatography tandem mass spectrometry and pharmacokinetic parameters calculated using noncompartmental analysis. Following SC and IM administration, all horses exhibited sweating, discomfort,...
Olave CJ, Ivester KM, Couetil LL, Kritchevsky JE, Tinkler SH, Mukhopadhyay A.Respirable dust exposure is linked to airway inflammation in racehorses. Feeding haylage may reduce dust exposure by 60-70%. The objective of this study was to compare dust exposure, airway cytology, and inflammatory cytokine concentrations between horses fed haylage or hay over 6 weeks while in training. Seven healthy Standardbred horses were randomly assigned to be fed alfalfa hay (n = 3) or grass-alfalfa mix haylage (n = 4) for six weeks while training on a treadmill. Dust exposure was measured gravimetrically at the breathing zone. Endotoxin and β-glucan concentrations in respirable dust ...
Hansen S, Laustsen L, Otten ND, Skovgaard K, Bech R, Byrgesen S, Hopster-Iversen C, Fjeldborg J.Alternative treatment options to glucocorticoids for equine asthma is desirable due to withdrawal time. The objective was to evaluate if serum and Respiratory Gene Technology (RGT), a commercial kit to produce autologous conditioned serum, was effective in reducing bronchoalveolar lavage (BAL) neutrophils and mast cells in racehorses with cytological evidence of mild equine asthma . Thirty-six Standardbred trotters in active training were enrolled in this randomized clinical trial; a healthy control group (n=11), a RGT group (n=12) and a serum group (n=13). Endoscopy including tracheal wash (T...
Caspers MK, Bell CD, Tatarniuk DM.Objective: The objective of this study is to evaluate the safety, efficacy, and owner satisfaction following electrosurgical ventriculocordectomy (EVC), in conjunction with prosthetic laryngoplasty, in equine clinical cases affected with left- or right-sided recurrent laryngeal neuropathy. Methods: Retrospective data analysis of clinical signalment, surgery, athletic outcome, intra- and postoperative complications, and postoperative examinations from clinical cases wherein EVC was performed in conjunction with traditional prosthetic laryngoplasty from one practice. Owners were contacted by pho...
The approach to respiratory diseases in donkeys is similar to that for horses; nevertheless, Bronchoalveolar lavage fluid (BALF) and tracheal wash cytology in this species have been described only a few times in the literature. To describe BALF cytological findings in a cohort of 24 healthy Amiata donkeys. Bronchoalveolar lavage (BAL) was carried out via standing sedation with a large animal where the BAL catheter passed blindly through the nasal passage into the trachea. The total nucleated cell count of the BALF was found similar to that already described in healthy horses and donkeys. No di...
Weller D, Franklin S, White P, Shea G, Fenner K, Wilson B, Wilkins C, McGreevy P.This article reports on the results of a survey of racehorse trainers (n = 112) outlining the reasons for tongue-tie (TT) and noseband (NB) use by Thoroughbred trainers (TBTs) (n = 72) and Standardbred trainers (SBTs) (n = 40). The study also investigated the reported effectiveness of TTs and possible complications arising from their use. Tongue-tie use was reported by 62.5% (n = 70) of racehorse trainers. The reasons for TT use varied between TBTs and SBTs. For TBTs, the most common reason for TT use was to prevent or reduce airway obstruction (72.3%, n = 34), followed closely by to prevent o...
Kim A, Sasaki N, Lee I, Seo JP.The purpose of this study was to assess the cardiorespiratory and behavioral responses to the combination of medetomidine and tramadol (M-T) or butorphanol (M-B) in standing laparoscopic ovariectomy in horses. One ovary was removed under M-T and the contralateral ovary was removed under M-B with at least 4 weeks between operations at random. Horses were sedated using intravenous medetomidine (5 µg/kg) followed by tramadol (1 mg/kg) or butorphanol (10 µg/kg) after 5 min. Sedation was maintained through the repeated injection of medetomidine (1 µg/kg) and tramadol (0.4 mg/kg) or medetomidine ...
Cooper CJ, Arroyo LG, Pearl DL, Hewson J, Lillie BN.A survey of Ontario horse breeders was conducted in 2016 and retrospectively asked farm-level management questions regarding herd sizes, vaccination, respiratory disease, and abortion over the years 2014 to 2015. A total of 88 farm owners completed the survey, reporting 857 broodmares. Using logistic regression modelling, management influences on vaccine use, and the reporting of respiratory disease or abortion was investigated. Having veterinary records and the reasons for breeding were significantly associated with the odds of an abortion even after controlling for broodmare herd size. The o...
Joó K, Duque Betancourt D, Vasquez Marin T, Parra Moyano LA.The dynamic upper airway functional (URT) problems of Colombian paso horses (CPH) have not been investigated in literature up to date. These horses perform special walking gaits with high poll flexion of the neck. Our goal is to evaluate the upper airway mechanics in CPH, showing abnormal respiratory sounds and poor performance during exercise. Resting and overground endoscopy was performed in 40 CPHs. Statistical analyses were performed using the sciPy package. One-tailed Fisher exact tests were used to check for positive contingency between each pair of upper respiratory tract disorder (P < ...
Crawford KL, Finnane A, Greer RM, Phillips CJC, Woldeyohannes SM, Perkins NR, Ahern BJ.There is international public concern regarding retirement of racehorses, including the reason for retirement and the outcome for horses after racing. However, there are currently no prospective studies investigating these factors. A recent independent inquiry in Queensland, Australia, highlighted that the true outcomes for horses after retirement from racing are largely unknown. Furthermore, there are currently no measures to monitor the outcome for racehorses and their welfare once they have left the care of the trainer. This study investigated these gaps in knowledge through a weekly survey...
Legere RM, Cohen ND, Poveda C, Bray JM, Barhoumi R, Szule JA, de la Concha-Bermejillo A, Bordin AI, Pollet J.Vaccines and therapeutics using in vitro transcribed mRNA hold enormous potential for human and veterinary medicine. Transfection agents are widely considered to be necessary to protect mRNA and enhance transfection, but they add expense and raise concerns regarding quality control and safety. We found that such complex mRNA delivery systems can be avoided when transfecting epithelial cells by aerosolizing the mRNA into micron-sized droplets. In an equine in vivo model, we demonstrated that the translation of mRNA into a functional protein did not depend on the addition of a polyethylenimine (...
Di Tocco J, Sabbadini R, Raiano L, Fani F, Ripani S, Schena E, Formica D, Massaroni C.In recent years, wearable devices for physiological parameter monitoring in sports and physical activities have been gaining momentum. In particular, some studies have focused their attention on using available commercial monitoring systems mainly on horses during training sessions or competitions. Only a few studies have focused on the jockey's physiological and kinematic parameters. Although at a glance, it seems jockeys do not make a lot of effort during riding, it is quite the opposite. Indeed, especially during competitions, they profuse a short but high intensity effort. To this extend, ...
Ohmura H, Mukai K, Matsui A, Takahashi T, Jones JH.Supramaximal exercise while inspiring different O gases may induce different responses in cardiopulmonary function at the same relative and/or absolute exercise intensity. The purpose of this study was to compare the effects of supramaximal exercise in hypoxia, normoxia and hyperoxia on cardiopulmonary function in Thoroughbred horses. Using a crossover design, five well-trained horses were made to run up a 6% grade on a treadmill at supramaximal speeds sustainable for approximately 110 sec (approximately 115% Omax) while breathing normoxic gas (NO, 21% O) or hypoxic gas (LO, 15.3% O) in random...
Douglas H, Hopster K, Cerullo M, Hopster-Iversen C, Stefanovski D, Driessen B.Flumazenil antagonises the actions of benzodiazepines. There has been no prior research specifically investigating this anaesthetic reversal agent for horses. Objective: To determine the effects of flumazenil administration in horses on (a) ventilatory parameters after midazolam-ketamine induction and maintenance with isoflurane in oxygen and on (b) the characteristics of recovery from general anaesthesia. Methods: Blinded, randomised, crossover experiment. Methods: Six horses were randomly assigned to receive high-dose flumazenil (F , 20 µg/kg), low-dose flumazenil (F , 10 µg/kg) and sali...
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...
Reef VB, Davidson EJ, Slack J, Stefanovski D.Cardiac arrhythmias are common in horses during exercise, especially immediately post-exercise. The objectives of this study were to: (1) describe the frequency and type of cardiac arrhythmias detected in horses during incremental high-speed treadmill exercise testing (ITET); (2) determine if arterial blood gas (ABG) changes at peak and immediately post-exercise were associated with arrhythmias; and (3) determine whether upper or lower airway disease was associated with exercising cardiac arrhythmias. Horses (n = 368) presenting for an ITET underwent resting and exercising upper airway endosco...
Joó K, Povázsai Á, Nyerges-Bohák Z, Szenci O, Kutasi O.It is important to treat the upper and lower respiratory tracts as a single unit, as lower respiratory tract diseases can often cause upper respiratory functional disorders, whereas upper respiratory obstructions could be a factor in lower respiratory problems. The present study aimed to investigate the hypothesis that asthmatic diseases may be an underlying cause of dorsal displacement of the soft palate in horses. Pleasure or sport horses (n = 57) with a history of asthmatic disease were incorporated in the study. All horses were examined in the exacerbation phase of the asthmatic disease. ...
Ben Hamouda S, Vargas A, Boivin R, Miglino MA, da Palma RK, Lavoie JP.Severe asthma is associated with an increased airway smooth muscle (ASM) mass and altered composition of the extracellular matrix (ECM). Studies have indicated that ECM-ASM cell interactions contribute to this remodeling and its limited reversibility with current therapy. Three-dimensional matrices allow the study of complex cellular responses to different stimuli in an almost natural environment. Our goal was to obtain acellular bronchial matrices and then develop a recellularization protocol with ASM cells. We studied equine bronchi as horses spontaneously develop a human asthma-like disease...
Marr CM, Franklin S, Garrod G, Wylie C, Smith L, Dukes-McEwan J, Bright J, Allen K.Exercise-associated cardiac rhythm disturbances are common, but there is a lack of evidence-based criteria on which to distinguish clinically relevant rhythm disturbances from those that are not. Objective: To describe and characterise rhythm disturbances during clinical exercise testing; to explore potential risk factors for these rhythm disturbances and to determine whether they influenced future racing. Methods: Retrospective cohort using a convenience sample. Methods: Medical records were reviewed from two clinical services to identify horses with poor performance and/or respiratory noise ...
Schuler G.The pituitary gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play a prominent role in the control of gonadal functions. Therefore, their use in the treatment of fertility disorders (e. g. anovulatory anestrus) as well as in biotechnology (e. g. superovulation, hormone programs for cycle synchronization) is of substantial interest. Preparations of FSH or LH are relatively expensive due to the laborious extraction from pituitary tissue and are therefore reserved for special indications. In primates and equids, the chorionic epithelium expresses an LH-like molecule...
Trenholme HN, Barletta M, Quandt JE, Reed RA, Kleine SA, Hofmeister EH.Low arterial oxygen is a common complication in anesthetized horses and placing the animal in reverse Trendelenburg (RT) position may treat hypoxemia. The objective of this study was to assess the arterial partial pressure of oxygen (PaO) in horses placed in a 5-degree RT compared to horizontal (H) position. Client-owned healthy horses (n = 60) undergoing elective surgeries were enrolled in a randomized controlled clinical study. Horses were sedated with butorphanol, an α-adrenoceptor agonist, ± acepromazine and induced with ketamine combined with a benzodiazepine, propofol, or guaifenesin...
Munsterman AS, Gillen AM, Coleridge MOD, Hanson RR.To evaluate the effect of changes in intra-abdominal pressure (IAP) on medial saphenous venous pressure (MSVP) and hemodynamics in normal horses. Methods: Experimental, in-vivo study. Methods: University Teaching Hospital. Methods: Convenience sample of 7 mixed breed horses; 5 geldings, and 2 mares. Methods: Pneumoperitoneum was induced in horses under standing sedation with carbon dioxide gas using a laparoscopic insufflator for a total of 60 minutes to simulate clinical elevation in IAP. Pressure was increased stepwise to 20 mm Hg over 30 minutes, and maintained at that pressure for 30 minu...
Warlick LM, Léguillette R, Kogan C, Gold JR, Bayly WM.Diagnosis and assessment of severity of exercise-induced pulmonary hemorrhage (EIPH) relies on postexercise visualization of fresh blood in the airways via tracheobronchoscopic examination (TBE) and/or counting erythrocytes in bronchoalveolar lavage fluid (BALFRBC). Determining the BALFRBC is more sensitive than TBE but its usefulness is hampered by the need to have BALFRBC counted at a laboratory. We explored the feasibility of evaluating the severity of EIPH by using a color chart comprised of five shades of red and matching those colors with the color of BALF immediately following collectio...
Laing G, Christley R, Stringer A, Ashine T, Cian F, Aklilu N, Newton R, Radford A, Pinchbeck G.Respiratory disease is a common cause for presentation of working horses to clinics in Ethiopia and a priority concern for owners. Objective: To identify risk factors for and association of pathogens with respiratory signs in working horses. Methods: Unmatched case-control study. Methods: Cases were those animals recently coughing (last 7 days) or observed with coughing, nasal discharge or altered respiration at the time of examination. A physical exam and respiratory endoscopy were performed including a tracheal wash sample to detect the presence of pathogens and serology performed on blood....
Wilkie BN.Effective resistance to respiratory tract infection depends principally on specific immunity on mucosal surfaces of the upper or lower respiratory tract. Respiratory tract immune response comprises antibody and cell-mediated systems and may be induced most readily by surface presentation of replicating agents but can result from parenteral or local presentation of highly immunogenic antigens. Upper and lower respiratory tract systems differ in immunologic competence, with the lungs having a greater inventory of protective mechanisms than the trachea or nose. Several effective vaccines have bee...
Olivier A, Nurton JP, Guthrie AJ.Wastage is the term used to describe the phenomenon of the loss of racehorses from conception to adulthood due to death or injuries (i.e. they never reach a race-track), or the days lost by racehorses due to not training or being withdrawn from a race. This epizoological study was conducted to investigate wastage in Thoroughbred horses used for flat racing in the Gauteng Province of South Africa. Data from 6 racing stables were recorded from 1 March 1993 to 28 February 1994. Each trainer completed a daily training record of the horses in his stable. This questionnaire included reasons why a ho...
Kinnison T, Cardwell JM.Inflammatory airway disease (IAD) is a commonly diagnosed but variably defined syndrome of equine lower airway inflammation. The most recent American College of Veterinary Internal Medicine (ACVIM) consensus statement, informed by research evidence, recommends a case definition based on clinical signs (poor performance or occasional coughing of at least 3 weeks duration), increased endoscopically-visible tracheal mucus, and bronchoalveolar lavage cytology, and proposes that the condition should be termed 'mild-moderate equine asthma' (mEA). In British Thoroughbred racehorses, research to date ...
Willoughby R, Ecker G, McKee S, Riddolls L, Vernaillen C, Dubovi E, Lein D, Mahony JB, Chernesky M, Nagy E.The response of horses exposed to three common respiratory viruses was studied by measuring tracheal mucociliary clearance rates in the trachea. Tracheal clearance rates (TCR) were determined before, during illness and following recovery in horses exposed to equine rhinovirus (ERhV-2), equine influenza virus (EIV) and equine herpesvirus (EHV-4) by means of lateral scintigraphs made following an injection of technetium-99m sulphide colloid into the tracheal lumen. In six horses exposed to ERhV-2, TCR remained within normal limits. Exposure to EIV resulted in reduced TCR in six of seven horses, ...
Olave CJ, Ivester KM, Couetil LL, Kritchevsky JE, Tinkler SH, Mukhopadhyay A.Respirable dust exposure is linked to airway inflammation in racehorses. Feeding haylage may reduce dust exposure by 60-70%. The objective of this study was to compare dust exposure, airway cytology, and inflammatory cytokine concentrations between horses fed haylage or hay over 6 weeks while in training. Seven healthy Standardbred horses were randomly assigned to be fed alfalfa hay (n = 3) or grass-alfalfa mix haylage (n = 4) for six weeks while training on a treadmill. Dust exposure was measured gravimetrically at the breathing zone. Endotoxin and β-glucan concentrations in respirable dust ...
Mancini DA, Mendonça RM, Dias AL, Mendonça RZ, Pinto JR.Trypsin is required in the hemagglutinin (HA) cleavage to in vitro influenza viruses activation. This HA cleavage is necessary for virus cell entry by receptor-mediated endocytosis. Bacteria in the respiratory tract are potential sources of proteases that could contribute to the cleavage of influenza virus in vivo. From 47 samples collected from horses, pigs, and from humans, influenza presence was confirmed in 13 and these samples demonstrated co-infection of influenza with flagellated bacteria, Stenotrophomonas maltophilia from the beginning of the experiments. Despite treatment with antibio...
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...
Kalpravidh M, Lumb WV, Wright M, Heath RB.The analgesic and behavioral effects of butorphanol (0.22 mg/kg), flunixin (2.2 mg/kg), levorphanol (0.033 mg/kg), morphine (0.66 mg/kg), and xylazine (2.2 mg/kg), given IM were observed in 8 ponies. These ponies were instrumented to measure response objectively to painful superficial and visceral stimuli. Effects on the cardiopulmonary system and rectal temperature also were evaluated in 6 of these ponies. Observations were conducted before drug injection (base-line values) and after injection at 30, 60, 120, 180, and 240 minutes. Xylazine provided the highest pain threshold for the first 60 ...
Klier J, May A, Fuchs S, Schillinger U, Plank C, Winter G, Gehlen H, Coester C.Recurrent airway obstruction (RAO) in horses has become a common problem in stabled horses in industrialized countries and deserves new therapeutic strategies. CpG-oligodeoxynucleotides (CpG-ODNs) were developed as effective immunostimulating agents to induce a Th2/Th1 shift. These agents showed a beneficial therapeutic effect in allergic diseases with predominant Th2 immunoresponse. CpG-ODN delivery by gelatin nanoparticles (GNPs) resulted in enhanced cellular uptake in murine and human in vitro studies and was a starting point for the present trial. The aim of this study was to identify an o...
Karagianni AE, Kapetanovic R, Summers KM, McGorum BC, Hume DA, Pirie RS.Alveolar macrophages (AMs) are the first line of defence against pathogens in the lungs of all mammalian species and thus may constitute appropriate therapeutic target cells in the treatment and prevention of opportunistic airway infections. Therefore, acquiring a better understanding of equine macrophage biology is of paramount importance in addressing this issue in relation to the horse. Objective: To compare the transcriptome of equine AMs with that of equine peritoneal macrophages (PMs) and to investigate the effect of lipopolysaccharide (LPS) on equine AM. Methods: Gene expression study o...
Derksen FJ, Stick JA, Scott EA, Robinson NE, Slocombe RF.The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at leas...
Scocco P, Pedini V.This study was performed to identify the equine respiratory tract areas which express the specific receptor for equine influenza virus; findings may be useful to provide new ways to treat the infectious disease. The present work aims to visualize in situ the presence of sialoderivatives in the horse respiratory tract in order to localize sialoderivatives acting as influenza virus receptors. To this purpose, nasal mucosae, trachea, bronchus and lung parenchyma were removed from 8 mature horses of both sexes. We performed sialic acid characterization by means of mild and strong periodate oxidati...
Manohar M.The present study was carried out on seven healthy ponies to examine the extent of blood flow in various inspiratory and expiratory muscles at rest and during maximal exertion as well as to determine the proportion of cardiac output needed to perfuse respiratory muscles during these conditions. Tissue blood flow was studied with 15 micron-diameter radionuclide-labeled microspheres injected into the left ventricle during steady conditions. The inspiratory and expiratory muscles comprised 2.41 and 3.05% of body weight, respectively, and received 6.17 and 3.75% of the cardiac output at rest. With...
Bennett RC, Steffey EP.REGIONAL ADMINISTRATION: There is limited, but convincing, evidence that epidural administration of morphine and some other mu-agonist opioids consistently relieves regional pain in horses. In addition, this effect is not accompanied by notable undesirable effects. On the other hand, a clinically important analgesic action has not been demonstrated for similarly administered kappa-agonist opioids. There has been little objective data presented to support the analgesic effectiveness of intra-articularly administered opioids in horses. However, the evidence of local opioid receptors legitimately...
Mama KR, Steffey EP, Pascoe PJ.To evaluate selected hemodynamic, respiratory, and behavioral responses to propofol in horses premedicated with xylazine or detomidine. Methods: Xylazine (0.5 and 1.0 mg/kg of body weight) was administered IV on different days to each of 6 horses prior to IV administration of propofol (2 mg/kg). In a second group of 6 horses, detomidine (15 and 30 micrograms/kg) was similarly studied. Methods: 2 groups of 6 mature healthy horses. Methods: Rectal temperature, heart and respiratory rates, arterial blood gas tensions, and direct arterial blood pressures were recorded before and at fixed intervals...
Holcombe SJ, Jacobs CC, Cook VL, Gandy JC, Hauptman JG, Sordillo LM.Endotoxemia models are used to study mechanisms and treatments of early sepsis. Repeated endotoxin exposures induce periods of endotoxin tolerance, characterized by diminished proinflammatory responses to lipopolysaccharide (LPS) and modulated production of proinflammatory cytokines. Repeated measure designs using equine endotoxemia models are rarely performed, despite the advantages associated with reduced variability, because the altered responsiveness would confound study results and because the duration of equine endotoxin tolerance is unknown. We determined the interval of endotoxin toler...
Day TK, Gaynor JS, Muir WW, Bednarski RM, Mason DE.One hundred sixty horses were anesthetized with xylazine, guaifenesin, thiamylal, and halothane for elective soft tissue and orthopedic procedures. Horses were randomly assigned to one of four groups. Group 1 (n = 40): Horses positioned in lateral (LRG1; n = 20) or dorsal (DRG1; n = 20) recumbency breathed spontaneously throughout anesthesia. Group 2 (n = 40): Intermittent positive pressure ventilation (IPPV) was instituted throughout anesthesia in horses positioned in lateral (LRG2; n = 20) or dorsal (DRG2; n = 20) recumbency. Group 3 (n = 40): Horses positioned in lateral (LRG3; n = 20) or d...
Ringer SK, Schwarzwald CC, Portier KG, Ritter A, Bettschart-Wolfensberger R.The objective of this study was to compare the cardiopulmonary effects of a xylazine or romifidine loading-dose, followed by a constant rate infusion (CRI) of the same α(2)-agonist. Nine research horses were treated in a randomized, blinded, crossover design with xylazine or romifidine. After instrumentation, a loading dose of intravenous xylazine (1mg/kg) or romifidine (80μg/kg) was administered, immediately followed by a CRI of xylazine (0.69mg/kg/h) or romifidine (30μg/kg/h) for a duration of 2h. Cardiopulmonary variables were recorded before bolus administration, during CRI, and for 1h ...
Doucet MY, Viel L.The objective of this study was to determine if a quantitative scoring system for evaluation of hemosiderin content of alveolar macrophages obtained by bronchoalevolar lavage provides a more sensitive test for the detection of exercise-induced pulmonary hemorrhage (EIPH) in horses than does endoscopy of the lower airways. A sample population composed of 74 Standardbred racehorses aged 2-5 years was used. Horses were grouped as either control (EIPH-negative) or EIPH-positive based on history and repeated postexertional endoscopic evaluation of the bronchial airways. Bronchoalveolar lavage was p...
Mazan MR, Hoffman AM, Manjerovic N.To compare response of horses to histamine bronchoprovocation (HBP), using total respiratory resistance (Rrs) measured by forced oscillatory mechanics (FOM) with dynamic compliance (Cdyn) and pulmonary resistance (RL) measured by the esophageal balloon method. Methods: 10 horses with various degrees of airway reactivity. Methods: The 2 methods for measuring airway responses to HBP were performed on separate days. Endpoints compared were increase of 150 or 200% of baseline Rrs (PC150Rrs, PC200Rrs) and to 150% of baseline RL (PC150RL) or decrease to 65% of baseline Cdyn (PC65Cdyn). Frequency dep...
Bosshard S, Gerber V.It is often assumed that horses with mild respiratory clinical signs, such as mucous nasal discharge and occasional coughing, have an increased risk of developing recurrent airway obstruction (RAO). Objective: Compared to horses without any clinical signs of respiratory disease, those with occasional coughing, mucous nasal discharge, or both have an increased risk of developing signs of RAO (frequent coughing, increased breathing effort, exercise intolerance, or a combination of these) as characterized by the Horse Owner Assessed Respiratory Signs Index (HOARSI 1-4). Methods: Two half-sibling ...
Mair TS, Batten EH, Stokes CR, Bourne FJ.The distribution of mucosa-associated lymphoid tissue along the equine respiratory tract was surveyed in light microscopical sections. Intra-epithelial lymphocytes and similar cells scattered in the lamina propria were identified in all sites from the nasal vestibule to bronchioles of 2 to 4 mm diameter. Isolated lymphoid patches, occasionally with nodules, were common in bronchioles, but the density of this bronchiole-associated lymphoid tissue (BRALT) varied between individual horses. Bronchus-associated lymphoid tissue (BALT) was infrequently encountered. In the upper respiratory tract, nod...
Mosing M, Marly-Voquer C, MacFarlane P, Bardell D, Böhm SH, Bettschart-Wolfensberger R, Waldmann AD.To evaluate the regional distribution of ventilation in horses during spontaneous breathing and controlled mechanical ventilation (CMV) using electrical impedance tomography (EIT). Methods: Prospective, experimental case series. Methods: Four anaesthetized experimental horses. Methods: Horses were anaesthetized with isoflurane in an oxygen-air mixture and medetomidine continuous rate infusion, placed in dorsal recumbency with an EIT belt around the thorax, and allowed to breathe spontaneously until PaCO reached 13.3 kPa (100 mmHg), when volume CMV was started. For each horse, the EIT signal wa...
Evans DL.This review addresses the physiology of performance horses in the context of functional tests aimed at assisting clinicians in the search for explanations of the individual's limitations, actual or perceived as below expectation. The intention is to assist clinicians who are faced frequently by owners or trainers seeking explanations for poor performance; and for research workers as a basis on which to proceed in their search for new methodologies, particularly those that can be applied in the field as for treadmill exercise. The review sets out fundamental physiological pathways, the entailme...
Franz R, Soliva CR, Kreuzer M, Hummel J, Clauss M.It is assumed that small herbivores produce negligible amounts of methane, but it is unclear whether this is a physiological peculiarity or simply a scaling effect. A respiratory chamber experiment was conducted with six rabbits (Oryctolagus cuniculus, 1.57±0.31 kg body mass) and six guinea pigs (Cavia porcellus, 0.79±0.07 kg) offered grass hay ad libitum. Daily dry matter (DM) intake and DM digestibility were 50±6 g kg⁻⁰·⁷⁵ d⁻¹ and 55±6% in rabbits and 59±11 g kg⁻⁰·⁷⁵ d⁻¹ and 61±3% in guinea pigs, respectively. Methane production was similar for both species (0.2...
Bowden A, Burford JH, Brennan ML, England GCW, Freeman SL.Colic is the most common emergency problem in the horse. An owner's ability to recognise colic and seek assistance is a critical first step in determining case outcome. Objective: The aim of this study was to assess horse owners' knowledge and opinions on recognising colic. Methods: Cross-sectional study. Methods: An online questionnaire was distributed to horse owners with open and closed questions on their knowledge of normal clinical parameters in the horse, confidence and approach to recognising colic (including assessment through case scenarios), and their demographics. Descriptive and ch...
Gollnick PD, Bertocci LA, Kelso TB, Witt EH, Hodgson DR.The effect of high-intensity exercise on the respiratory capacity of skeletal muscle was studied in horses which ran five 600-m bouts on a track with 2 min of rest between exercise bouts, or once to fatigue on a treadmill at an intensity that elicited the maximal oxygen uptake. Venous blood and biopsy samples of the middle gluteal muscle were collected at rest, after each exercise bout, and 30 and 60 min post-exercise. Blood samples were analyzed for lactate concentration and pH and muscle samples for metabolites, pH, and respiratory capacity. Venous blood and muscle pH declined to 6.91 +/- 0....
Stucchi L, Alberti E, Stancari G, Conturba B, Zucca E, Ferrucci F.Mild-moderate equine asthma (MEA) is a common disease of young racehorses characterized by inflammation of the lower airways diagnosed by cytological examination of bronchoalveolar lavage fluid (BALF), and it is considered an important cause of poor performance. The most common parameter of athletic capacity associated with horse performance is the speed at 4 mmol/L of lactate (VLA4). The aim of the present work was to evaluate the relation between the different BALF inflammatory cells and VLA4 in racehorses affected by MEA. A population of Standardbred racehorses that underwent an accurate pr...
Olguin Perglione C, Golemba MD, Torres C, Barrandeguy M.Equine influenza virus (EIV) is considered the most important respiratory pathogen of horses as outbreaks of the disease lead to substantial economic losses. The H3N8 EIV has caused respiratory disease in horses across the world, including South American countries. Nucleotide and deduced amino acid sequences for the complete haemagglutinin gene of the H3N8 EIV detected in South America since 1963 were analyzed. Phylogenetic and Bayesian coalescent analyses were carried out to study the origin, the time of the most recent common ancestors (tMRCA), the demographic and the phylogeographic pattern...
