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Topic:Equine Diseases

Equine diseases encompass a wide range of health conditions that can affect horses, including infectious diseases, metabolic disorders, and genetic conditions. These diseases can impact the overall health, performance, and well-being of horses. Common equine diseases include equine influenza, equine herpesvirus, laminitis, and equine metabolic syndrome. Diagnosis and management of these diseases often require a combination of clinical evaluation, laboratory testing, and appropriate treatment strategies. This page gathers peer-reviewed research studies and scholarly articles that explore the etiology, pathophysiology, diagnosis, and treatment options for various equine diseases, providing valuable insights for veterinarians and researchers in the field.
Choosing the Best Approach to Wound Management and Closure.
The Veterinary clinics of North America. Equine practice    October 17, 2018   Volume 34, Issue 3 499-509 doi: 10.1016/j.cveq.2018.07.005
Kamus L, Theoret C.This article aims to help the practitioner by providing the tools to decide which type of closure or healing is best in a given situation. An overview of the main criteria and the different approaches to wound closure is presented. Each wound must be considered as a unique problem that requires a clinician to take into account all of its characteristics and limits to determine the best management approach.
Species distribution and seasonal dynamics of equine tick infestation in two Mediterranean climate niches in Israel.
Parasites & vectors    October 16, 2018   Volume 11, Issue 1 546 doi: 10.1186/s13071-018-3093-0
Tirosh-Levy S, Gottlieb Y, Apanaskevich DA, Mumcuoglu KY, Steinman A.Ticks are important ectoparasites of horses that can affect animal welfare and vector several infectious, including zoonotic, diseases. In order to investigate the species distribution, epidemiology and seasonal dynamics of ticks infesting horses in Israel, 3267 ticks were collected from 396 horses in 24 farms across the country from July 2014 to June 2015. Results: Ticks were found on 50% of the farms and on 25% of the horses, with Hyalomma being the most prevalent genus (70% of ticks). Pasture was the most prominent risk factor for tick infestation (99% of ticks, P < 0.001), and is repres...
A survey of Dictyocaulus arnfieldi (Nematoda) infections in equids in Urmia region, Iran.
Annals of parasitology    October 15, 2018   Volume 64, Issue 3 235-240 doi: 10.17420/ap6403.158
Saadi, A, Tavassoli, M, Dalir-Naghadeh, B, Samiei A.Dictyocaulus arnfieldi is a lungworm commonly found in equids; however, relatively little is known about it. The aim of the present study was to establish the prevalence of equine lungworms in naturally-infected working and sporting horses, donkeys and mules in rural areas of Urmia, northwest Iran. The fecal samples were collected from 299 working horses, 57 sporting horses, 66 donkeys and 37 mules during the period March 2014 to June 2016. The collected fecal samples were processed within 48 hours following rectal sampling. The larval count/g (LPG) of feces was determined using the Baermann t...
Comparison of Metzenbaum scissors and Y-shaped fasciotome for deep metatarsal fasciotomy for the treatment of proximal suspensory ligament desmopathy in horses.
Veterinary surgery : VS    October 15, 2018   Volume 48, Issue 1 57-63 doi: 10.1111/vsu.13111
Sidhu ABS, Rosanowski SM, Davis AM, Griffith JF, Robinson P.To quantitate the iatrogenic injury associated with deep plantar metatarsal fasciotomy performed with Metzenbaum scissors compared with a Y-shaped fasciotome. Methods: Experimental ex vivo surgical study. Methods: Cadaveric hind limbs (n = 20) from 10 sound thoroughbred racehorses. Methods: A plantar metatarsal fasciotomy was performed, extending from the proximal extent of the deep metatarsal fascia, distally. Hind limbs were randomly assigned to 2 groups, undergoing fasciotomy with straight Metzenbaum scissors (n = 10) or a Y-shaped fasciotome (n = 10). Magnetic resonance imaging...
Improvement of recombinant-truncated Burkholderia motility protein A (BimA)-based indirect ELISA for equine glanders.
Journal of immunoassay & immunochemistry    October 12, 2018   Volume 39, Issue 5 565-575 doi: 10.1080/15321819.2018.1523800
Singh S, Dohre SK, Kamthan A, Pal V, Karothia BS, Singha HS, Kumar S.Glanders is a contagious and highly fatal disease of equines with zoonotic potential. It is caused by a Gram-negative, nonmotile bacterium Burkholderia mallei. Complement fixation test (CFT) is one of the most commonly used tests for diagnosis of glanders; however, it has some limitations. A recombinant-truncated Burkholderia intracellular motility A (BimA) protein-based indirect enzyme-linked immunosorbent assay (iELISA) was previously reported by us for glanders diagnosis, which has been re-optimized in this study using a panel of glanders positive (n = 75) and glanders negative (n = 227...
Generation of an equine biobank to be used for Functional Annotation of Animal Genomes project.
Animal genetics    October 11, 2018   Volume 49, Issue 6 564-570 doi: 10.1111/age.12717
Burns EN, Bordbari MH, Mienaltowski MJ, Affolter VK, Barro MV, Gianino F, Gianino G, Giulotto E, Kalbfleisch TS, Katzman SA, Lassaline M, Leeb T....The Functional Annotation of Animal Genomes (FAANG) project aims to identify genomic regulatory elements in both sexes across multiple stages of development in domesticated animals. This study represents the first stage of the FAANG project for the horse, Equus caballus. A biobank of 80 tissue samples, two cell lines and six body fluids was created from two adult Thoroughbred mares. Ante-mortem assessments included full physical examinations, lameness, ophthalmologic and neurologic evaluations. Complete blood counts and serum biochemistries were also performed. At necropsy, in addition to tiss...
Sequence variant analysis of RNA sequences in severe equine asthma.
PeerJ    October 11, 2018   Volume 6 e5759 doi: 10.7717/peerj.5759
Tessier L, Côté O, Bienzle D.Severe equine asthma is a chronic inflammatory disease of the lung in horses similar to low-Th2 late-onset asthma in humans. This study aimed to determine the utility of RNA-Seq to call gene sequence variants, and to identify sequence variants of potential relevance to the pathogenesis of asthma. Methods: RNA-Seq data were generated from endobronchial biopsies collected from six asthmatic and seven non-asthmatic horses before and after challenge (26 samples total). Sequences were aligned to the equine genome with Spliced Transcripts Alignment to Reference software. Read preparation for sequenc...
Safety and immunogenicity of plant-produced African horse sickness virus-like particles in horses.
Veterinary research    October 11, 2018   Volume 49, Issue 1 105 doi: 10.1186/s13567-018-0600-4
Dennis SJ, O'Kennedy MM, Rutkowska D, Tsekoa T, Lourens CW, Hitzeroth II, Meyers AE, Rybicki EP.African horse sickness (AHS) is caused by multiple serotypes of the dsRNA AHSV and is a major scourge of domestic equids in Africa. While there are well established commercial live attenuated vaccines produced in South Africa, risks associated with these have encouraged attempts to develop new and safer recombinant vaccines. Previously, we reported on the immunogenicity of a plant-produced AHS serotype 5 virus-like particle (VLP) vaccine, which stimulated high titres of AHS serotype 5-specific neutralizing antibodies in guinea pigs. Here, we report a similar response to the vaccine in horses. ...
Validation of a new experimental model for assessing drug efficacy against infection with Trypanosoma equiperdum in horses.
Veterinary parasitology    October 9, 2018   Volume 263 27-33 doi: 10.1016/j.vetpar.2018.10.005
Hébert L, Guitton E, Madeline A, Géraud T, Carnicer D, Lakhdar L, Pitel PH, Coste M, Laloy E, Giraudet A, Zientara S, Büscher P, Laugier C, Hans A....Trypanosoma equiperdum, the causative agent of dourine, may affect the central nervous system, leading to neurological signs in infected horses. This location protects the parasite from most (if not all) existing chemotherapies. In this context, the OIE terrestrial code considers dourine as a non-treatable disease and imposes a stamping-out policy for affected animals before a country may achieve its dourine-free status. The use of practices as drastic as euthanasia remains controversial, but the lack of a suitable tool for studying a treatment's efficacy against dourine hampers the developmen...
Genotype imputation accuracy in multiple equine breeds from medium- to high-density genotypes.
Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie    October 9, 2018   Volume 135, Issue 6 420-431 doi: 10.1111/jbg.12358
Chassier M, Barrey E, Robert C, Duluard A, Danvy S, Ricard A.Genotype imputation is now a key component of genomic analyses as it increases the density of available genotypes within a population. However, many factors can influence imputation accuracy. The aim of this study was to assess and compare the accuracy of imputation of high-density genotypes (Affymetrix Axiom Equine genotyping array, 670,806 SNPs) from two moderate-density genotypes (Illumina Equine SNP50 BeadChip, 54,602 SNPs and Illumina Equine SNP70 BeadChip, 65,157 SNPs), using single-breed or multiple-breed reference sets. Genotypes were available from five groups of horse breeds: Arab (A...
Objective pain assessment in horses (2014-2018).
Veterinary journal (London, England : 1997)    October 9, 2018   Volume 242 1-7 doi: 10.1016/j.tvjl.2018.10.001
van Loon JPAM, Van Dierendonck MC.In recent decades, much effort has been invested in scientific studies of objective and reliable assessment of pain in horses. Various types of pain assessment tools have been described and (partly) validated for different types of pain in horses. Currently, composite pain scales and facial expression-based pain scales seem to be the most promising tools for pain assessment in horses and numerous studies have recently been published on the use of these pain scales in horses. Therefore, this narrative review mainly focusses on these two types of pain scales and on the studies that have appeared...
Equine bone marrow-derived mesenchymal stem cells: optimization of cell density in primary culture.
Stem cell investigation    October 9, 2018   Volume 5 31 doi: 10.21037/sci.2018.09.01
Zahedi M, Parham A, Dehghani H, Kazemi Mehrjerdi H.The primary cell seeding density of bone marrow-derived mononuclear cells (BM-MNCs) affects several cellular behaviors, including attachment to the culture dish, proliferation, and differentiation. Methods: The aim of this study was to determine the best density of equine BM-MNCs in primary culture (P0) for obtaining the maximum bone marrow-derived mesenchymal stem cell (BM-MSC) yields at the end of P0. Bone marrow samples of two healthy mares were aspirated. The MNCs were isolated and cultured at different densities (1×10, 2×10, 4×10, 8×10, and 1×10 cells/cm). Within the 7 and 14 days af...
Characterization of Apoptosis, Autophagy and Oxidative Stress in Pancreatic Islets Cells and Intestinal Epithelial Cells Isolated from Equine Metabolic Syndrome (EMS) Horses.
International journal of molecular sciences    October 8, 2018   Volume 19, Issue 10 3068 doi: 10.3390/ijms19103068
Kornicka K, Śmieszek A, Szłapka-Kosarzewska J, Irwin Houston JM, Roecken M, Marycz K.Endocrine disorders are becoming an increasing problem in both human and veterinary medicine. In recent years, more and more horses worldwide have been suffering from equine metabolic syndrome (EMS). This metabolic disorder is characterized by pathological obesity, hyperinsulinaemia, hyperglycaemia and insulin resistance. Although metabolic disorders, including diabetes, have been extensively studied, there are still no data on the molecular effects of EMS in horses. Thus, the aim of this study was to evaluate apoptosis, oxidative stress, autophagy and microRNA (miR) expression in multipotent ...
A single dose of African horse sickness virus (AHSV) VP2 based vaccines provides complete clinical protection in a mouse model.
Vaccine    October 8, 2018   Volume 36, Issue 46 7003-7010 doi: 10.1016/j.vaccine.2018.09.065
Aksular M, Calvo-Pinilla E, Marín-López A, Ortego J, Chambers AC, King LA, Castillo-Olivares J.African horse sickness is a severe, often fatal, arboviral disease of equids. The control of African horse sickness virus (AHSV) in endemic countries is based currently on the use of live attenuated vaccines despite some biosafety concerns derived from its biological properties. Thus, experimental vaccination platforms have been developed over the years in order to avoid the biosafety concerns associated with the use of attenuated vaccines. Various studies showed that baculovirus-expressed AHSV-VP2 or modified Vaccinia Ankara virus expressing AHSV-VP2 (MVA-VP2) induced virus neutralising antib...
Equine asthma: Integrative biologic relevance of a recently proposed nomenclature.
Journal of veterinary internal medicine    October 7, 2018   Volume 32, Issue 6 2088-2098 doi: 10.1111/jvim.15302
Bond S, Léguillette R, Richard EA, Couetil L, Lavoie JP, Martin JG, Pirie RS.The term "equine asthma" has been proposed as a unifying descriptor of inflammatory airway disease (IAD), recurrent airway obstruction (RAO), and summer pasture-associated obstructive airway disease. Whilst the term will increase comprehensibility for both the lay and scientific communities, its biologic relevance must be compared and contrasted to asthma in human medicine, recognizing the limited availability of peer-reviewed equine-derived data, which are largely restricted to clinical signs, measures of airway obstruction and inflammation and response to therapy. Such limitations constrain ...
Dysregulation of Cortisol Metabolism in Equine Pituitary Pars Intermedia Dysfunction.
Endocrinology    October 6, 2018   Volume 159, Issue 11 3791-3800 doi: 10.1210/en.2018-00726
Morgan RA, Keen JA, Homer N, Nixon M, McKinnon-Garvin AM, Moses-Williams JA, Davis SR, Hadoke PWF, Walker BR.Equine Cushing disease [pituitary pars intermedia dysfunction (PPID)] is a common condition of older horses, but its pathophysiology is complex and poorly understood. In contrast to pituitary-dependent hyperadrenocorticism in other species, PPID is characterized by elevated plasma ACTH but not elevated plasma cortisol. In this study, we address this paradox and the hypothesis that PPID is a syndrome of ACTH excess in which there is dysregulation of peripheral glucocorticoid metabolism and binding. In 14 horses with PPID compared with 15 healthy controls, we show that in plasma, cortisol levels...
Proteome and transcriptome profiling of equine myofibrillar myopathy identifies diminished peroxiredoxin 6 and altered cysteine metabolic pathways.
Physiological genomics    October 5, 2018   Volume 50, Issue 12 1036-1050 doi: 10.1152/physiolgenomics.00044.2018
Valberg SJ, Perumbakkam S, McKenzie EC, Finno CJ.Equine myofibrillar myopathy (MFM) causes exertional muscle pain and is characterized by myofibrillar disarray and ectopic desmin aggregates of unknown origin. To investigate the pathophysiology of MFM, we compared resting and 3 h postexercise transcriptomes of gluteal muscle and the resting skeletal muscle proteome of MFM and control Arabian horses with RNA sequencing and isobaric tags for relative and absolute quantitation analyses. Three hours after exercise, 191 genes were identified as differentially expressed (DE) in MFM vs. control muscle with >1 log fold change (FC) in genes involve...
Ocular abnormalities in a herd of Old Kladruber Horses: A cross-sectional study.
Veterinary ophthalmology    October 5, 2018   Volume 22, Issue 4 462-469 doi: 10.1111/vop.12614
Andrysikova R, Pot S, Rüegg S, Markova J, Horackova E, Kolos F, Voelter K, Spiess B.To screen a closed herd of the Old Kladruber Horses (OKH) for the prevalence of ocular disorders and report normal ocular variations. Methods: Two hundred and sixty-one horses, 122 Old Kladruber Gray Horses, and 139 Old Kladruber Black Horses owned by the National Stud Farm Kladruby nad Labem, Czech Republic, were included in the study with signalment and pedigree information recorded. Methods: Bilateral ocular examination of manually restrained horses was performed in a darkened environment by a single examiner (RA), using a portable slit-lamp biomicroscope, direct ophthalmoscope, and monocul...
Ganglion Cytology: A Novel Rapid Method for the Diagnosis of Equine Dysautonomia.
Veterinary pathology    October 5, 2018   Volume 56, Issue 2 244-247 doi: 10.1177/0300985818806051
Piccinelli C, Jago R, Milne E.Equine dysautonomia (grass sickness) is characterized by autonomic neuronal degeneration and is often fatal. As outbreaks occur, rapid diagnosis is essential but confirmation currently requires histological examination. This study evaluated diagnostic accuracy of cytological examination of cranial cervical ganglion (CCG) scrapings for dysautonomia diagnosis. CCG smears from 20 controls and 16 dysautonomia cases were stained with May-Grünwald Giemsa (MGG), hematoxylin and eosin (HE), and cresyl fast violet (CFV), with HE-stained histological sections of CCG as gold standard for diagnosis. Exam...
Effect of transforming growth factor -β1 on α-smooth muscle actin and collagen expression in equine endometrial fibroblasts.
Theriogenology    October 4, 2018   Volume 124 9-17 doi: 10.1016/j.theriogenology.2018.10.005
Szóstek-Mioduchowska AZ, Lukasik K, Skarzynski DJ, Okuda K.Transforming growth factor (TGF)-β1 not only regulates cell growth, development, and tissue remodeling, but it also participates in the pathogenesis of tissue fibrosis. In the equine endometrium, the concentration of TGF-β1 is correlated with endometrosis (equine endometrial fibrosis). In other tissues, TGF-β1 induces differentiation of many cell types into myofibroblasts. These cells are characterized by α-smooth muscle actin (α-SMA) expression and an ability to deposit excessive amounts of extracellular matrix (ECM) components. The aim of the study was to determine whether TGF-β1 plays...
In vitro culture supplementation of EGF for improving the survival of equine preantral follicles.
In vitro cellular & developmental biology. Animal    October 3, 2018   Volume 54, Issue 10 687-691 doi: 10.1007/s11626-018-0296-9
Max MC, Bizarro-Silva C, Búfalo I, González SM, Lindquist AG, Gomes RG, Barreiros TRR, Lisboa LA, Morotti F, Seneda MM.Folliculogenesis is a process of development and maturation of the ovarian follicles, being essential for the maintenance of fertility. In in vivo conditions, 99.9% of the follicles of an ovary do not ovulate and undergo atresia. In order to minimize this loss and to clarify the existing mechanisms, a technique was developed that allows for the in vitro follicular development. The objective of this study was to evaluate the effects of different epidermal growth factor (EGF) concentrations on the in vitro culturing of equine preantral follicles. Ovaries (n = 10) were collected from a local ...
Preimplantation factor modulates acute inflammatory responses of equine endometrium.
Veterinary medicine and science    October 1, 2018   Volume 4, Issue 4 351-356 doi: 10.1002/vms3.126
Nash DM, Paddison J, Davies Morel MCG, Barnea ER.Persistent mating-induced endometritis (PMIE) is a significant cause of mare infertility hence its treatment would advance the management of susceptible mares. Preimplantation factor (PIF) is secreted by viable embryos, including human, mouse and cattle, and is essential for maternal immune-tolerance without immune-suppression by modulating inflammation. This preliminary study aimed to test whether PIF exerts inflammatory-modulating properties upon equine endometrium challenged with Escherichia coli-derived lipopolysaccharide (LPS) using endometrial explant culture. Follicular (n = 3), lutea...
Dynamic changes in gene expression and signalling during trophoblast development in the horse.
Reproduction (Cambridge, England)    October 1, 2018   Volume 156, Issue 4 313–330 doi: 10.1530/REP-18-0270
Read JE, Cabrera-Sharp V, Offord V, Mirczuk SM, Allen SP, Fowkes RC, de Mestre AM.Equine chorionic girdle trophoblast cells play important endocrine and immune functions critical in supporting pregnancy. Very little is known about the genes and pathways that regulate chorionic girdle trophoblast development. Our aim was to identify genes and signalling pathways active in vivo in equine chorionic girdle trophoblast within a critical 7-days window. We exploited the late implantation of the equine conceptus to obtain trophoblast tissue. An Agilent equine 44K microarray was performed using RNA extracted from chorionic girdle and chorion (control) from equine pregnancy days 27, ...
Clinical insights: Recent developments in equine articular disease (2016-2018).
Equine veterinary journal    September 29, 2018   Volume 50, Issue 6 705-707 doi: 10.1111/evj.13016
Clegg P.No abstract available
Cytological and bacteriological sampling from filters used for embryo recovery to evaluate the uterine status of donor mares.
Acta veterinaria Hungarica    September 29, 2018   Volume 66, Issue 3 462-473 doi: 10.1556/004.2018.041
Pérez-Marín CC, Vizuete G, Borge C, Galisteo JJ.While testing for uterine bacterial infection is usually performed prior to artificial insemination (AI), samples taken during or after embryo flushing are generally not assessed either in subfertile and old mares or in fertile mares, even though knowledge of the status of the uterine environment in which the embryo is to develop would help to predict the outcome of embryo transfer programmes. The presence of bacteria and inflammatory cells in the liquid retained in the filter after uterine flushing in donors was determined at the moment of embryo recovery. Primarily, a group of mares (n = 8) ...
In vitro developmental competence of horse embryos derived from oocytes with a different corona radiata cumulus-oocyte morphology.
Animal reproduction science    September 29, 2018   Volume 198 233-237 doi: 10.1016/j.anireprosci.2018.09.023
Merlo B, Mari G, Iacono E.The increase in demand for in vitro produced horse embryos is fostering the development of commercial laboratories for this purpose. Nevertheless, blastocyst production after intracytoplasmic sperm injection (ICSI) is still not as great as desired in most of these laboratories. In relation to horse oocyte classification, both expanded and compact cumulus-oocyte-complexes (COCs) are used for in vitro embryo production. The aim of this study was to compare in vitro embryo developmental capacity of COCs from horses including those with only the corona radiata, frequently collected after aspiratio...
Effect of human tubal fluid medium and hyperactivation inducers on stallion sperm capacitation and hyperactivation.
Reproduction in domestic animals = Zuchthygiene    September 29, 2018   Volume 54, Issue 2 184-194 doi: 10.1111/rda.13328
Arroyo-Salvo C, Sanhueza F, Fuentes F, Treulén F, Arias ME, Cabrera P, Silva M, Felmer R.Conventional in vitro fertilization has not yet been implemented in the equine species. One of the main reasons has been the inability to develop a culture medium and incubation conditions supporting high levels of stallion sperm capacitation and hyperactivation in vitro. Although different culture media have been used for this purpose, human tubal fluid (HTF) medium, widely used in the manipulation of human and mice gametes, has not been reported so far in stallion sperm culture. The first part of this study aimed to compare HTF and Whitten's media on different stallion sperm quality and capa...
Identification of loci affecting sexually dimorphic patterns for height and recurrent laryngeal neuropathy risk in American Belgian Draft Horses.
Physiological genomics    September 28, 2018   Volume 50, Issue 12 1051-1058 doi: 10.1152/physiolgenomics.00068.2018
Brooks SA, Stick J, Braman A, Palermo K, Robinson NE, Ainsworth DM.Equine recurrent laryngeal neuropathy (RLN) is a bilateral mononeuropathy with an unknown etiology. In Thoroughbreds (TB), we previously demonstrated that the haplotype association for height (LCORL/NCAPG locus on ECA3, which affects body size) and RLN was coincident. In the present study, we performed a genome-wide association scan (GWAS) for RLN in 458 American Belgian Draft Horses, a breed fixed for the LCORL/NCAPG risk alelle. In this breed, RLN risk is associated with sexually dimorphic differences in height, and we identified a novel locus contributing to height in a sex-specific manner:...
Effects of enzyme and cryoprotectant concentrations on yield of equine adipose-derived multipotent stromal cells.
American journal of veterinary research    September 27, 2018   Volume 79, Issue 10 1100-1112 doi: 10.2460/ajvr.79.10.1100
Duan W, Lopez MJ.OBJECTIVE To evaluate effects of various concentrations of collagenase and dimethyl sulfoxide (DMSO) on yield of equine adipose-derived multipotent stromal cells (ASCs) before and after cryopreservation. SAMPLE Supragluteal subcutaneous adipose tissue from 7 Thoroughbreds. PROCEDURES Tissues were incubated with digests containing 0.1%, 0.05%, or 0.025% type I collagenase. Part of each resulting stromal vascular fraction was cryopreserved in 80% fetal bovine serum (FBS), 10% DMSO, and 10% Dulbecco modified Eagle medium F-12 and in 95% FBS and 5% DMSO. Half of each fresh and cryopreserved hetero...
Efficacy of an alveolar recruitment maneuver for improving gas exchange and pulmonary mechanics in anesthetized horses ventilated with oxygen or a helium-oxygen mixture.
American journal of veterinary research    September 27, 2018   Volume 79, Issue 10 1021-1027 doi: 10.2460/ajvr.79.10.1021
Hopster K, D○ LR, Hopster-Iversen CCS, Driessen B.OBJECTIVE To evaluate efficacy of an alveolar recruitment maneuver (ARM) with positive end-expiratory pressures (PEEPs) in anesthetized horses ventilated with oxygen or heliox (70% helium and 30% oxygen). ANIMALS 6 healthy adult horses. PROCEDURES In a randomized crossover study, horses were anesthetized and positioned in dorsal recumbency. Volume-controlled ventilation was performed with heliox or oxygen (fraction of inspired oxygen [Fio] > 90%). Sixty minutes after mechanical ventilation commenced, an ARM with PEEP (0 to 30 cm HO in steps of 5 cm HO every 5 minutes, followed by incrementa...