Dissertations / Theses: 'Equine veterinary science'

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Gaffney, Megan. "Prognosis of Equine Limb Fractures Based on Type and Location." Thesis, Rochester Institute of Technology, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10842231.

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Horses are powerful animals: a galloping horse’s forefoot hits the ground with an average of about 2,000 pounds of force. This can result in many kinds of injuries. To work with and love a horse properly, the owner needs to understand more than just grooming and feeding. Owners must understand how the horse operates, particularly the structure and workings of the horse’s legs, to comprehend how a broken leg impairs a horse. This understanding enables the owner to work well with a veterinarian in determining the best course of treatment for an injury.

A review of the current veterinary literature and public resources showed that illustrated information regarding types of limb fractures in horses, options for repair and post-operative outcomes, that can be easily understood by the lay person, do not exist. The lack of sufficiently illustrated resources covering this topic indicates a great need for this valuable information.

The objective of this thesis is to illustrate common types of fractures, to assist owners in understanding different types of fractures, repair options, and possible outcomes of any intervention. Three cases, each with a specific type of fracture, were analyzed to develop understanding of the damage, the impact on the horse and surgical options versus the need for euthanasia. The finished product of this research was two posters, one for repair and the other for euthanasia, designed to enhance the owner’s comprehension of the injuries.

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Dacre, Ian Thomas. "A pathological, histological and ultrastructural study of diseased equine cheek teeth." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/15808.

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The examination of 220 normal and 130 diseased equine (extracted) cheek teeth was performed using a variety of traditional and novel imaging techniques primarily to assess the aetiopathogenesis of the important dental disorders of apical infection and "idiopathic" dental fracture. Optimal settings for radiography and computer axial scanning of normal and diseased cheek teeth were determined. It was found that standard radiography of extracted cheek teeth was very poor at identifying intradental anatomical or pathological features, whilst computer axial scanning gave accurate information on both normal and abnormal radiographic features. Newly established histological techniques allowed preparation of undecalcified sections of 4-6 μm thickness, and undecalcified sections of 50-60 μm thickness. The current classification of equine dentine was modified, with primary, regular secondary, irregular secondary and tertiary dentine all being categorised separately. Previously undescribed histological features of normal and diseased equine teeth were identified such as dentinal pearls, interglobular dentine, caries and the presence of pioneer micro-organisms. The normal endodontic anatomy of all 24 cheek teeth was established, with individual pulp horns being identified using a unique numbering system. Anatomical parameters of dentine were established for normal cheek teeth, and these were compared to those of apically infected cheek teeth. A decreased presence of primary and secondary dentine, predentine and intertubular dentine was found in diseased teeth compared with normal cheek teeth, but increased number of resting lines were present in diseased cheek teeth. Analysis of 50 individual apically infected cheek teeth showed anachoretic pulpitis to be the most common aetiology, with occlusal pulp exposure often being a secondary finding. Apical infection caused by periodontal disease or infundibular caries was uncommon finding. Fracture patterns to the clinical crown of equine cheek teeth were grouped, with most fractures involving the buccal pulp horns of both maxillary and mandibular cheek teeth.

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Berglund, Alix Kay. "Investigating the Use of TGF-beta2 to Downregulate MHC Expression and Reduce the Immunogenicity of Equine Bone Marrow-derived Mesenchymal Stem Cells." Thesis, North Carolina State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10970022.

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Allogeneic bone marrow-derived mesenchymal stem cells (MSCs) are a promising cell therapy for effective and efficient treatment of various inflammatory and immunemediated diseases. While the prevailing dogma has been that MSCs are immune privileged, very few studies have controlled for MHC haplotype or adequately measured MSC immunogenicity in vitro or in vivo. Controlled studies have found that major histocompatibility complex (MHC)-mismatched MSCs evoke both cell-mediated and humoral immune responses in vivo. Microcytotoxicity assays were used to show that horses injected with MHC-mismatched MSCs generate cytotoxic alloantibodies capable of killing MSCs as early as 7-days post-transplantation. Rejection of MSCs likely leads to reduced therapeutic efficacy and the development of strategies to avoid allorecognition and rejection are necessary to provide safe and efficacious allogeneic therapy.

Downregulation of MHC expression allows cells to avoid immune surveillance and may enhance the ability of MSCs to avoid allorecognition and rejection. Transforming growth factor-β2 (TGF-β2) has been shown to downregulate MHC surface expression in various cell types. In agreement with what has been demonstrated in other cell types, TGF-β2 treatment significantly reduced constitutive MHC I and MHC II surface expression and partially blocked IFN-γ-induced MHC expression on equine MSCs. TGF-β2 treatment did not significantly affect the morphology, cell surface markers, viability, or secretion of TGF- β1 and TGF-β2, but did increase the cell yield from cultures. This data indicates that TGF-β2 may reduce MSC immunogenicity without altering the immunomodulatory properties of the cells.

The immunomodulatory capabilities of TGF-β2-treated MSCs were analyzed in modified one-way mixed leukocyte reactions and ELISAs. Naive and TGF-β2-treated MSCs both significantly reduced T cell proliferation as measured by the relative division index and relative CFSE geometric mean fluorescent intensity attenuation. Similar amounts of PGE2 and TGF-β2 were also measured in the supernatant of MLRs with naive and TGF-β2-treated MSCs. This supports that TGF-β2 treatment does not negatively affect the immunomodulatory properties of equine MSCs, which are critical for therapeutic function and evading immune responses in vivo.

In conclusion, although MHC-mismatched equine MSCs are immunogenic in vivo, MHC I and MHC II surface expression can be manipulated by treating cells with TGF-β2 in vitro. Downregulate of MHC surface expression is a promising strategy for enhancing the ability of MSCs to evade immune responses allowing for allogenic use clinically without the risk of immune rejection. The ability of TGF-β2-treated MSCs to avoid immune rejection should continue to be investigated in vitro and in vivo along with the mechanism by which TGF-β2 downregulates MHC expression.

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Al, Mohamad Zakriya Ali E. "Quantitative assessment of the biochemical composition of equine cartilage using 7T ultra-high field magnetic resonance imaging (MRI) techniques." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/8227/.

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Equine fetlock region disease is responsible for significant morbidity and mortality. Diagnosis of sesamoidean ligament, cartilage and subchondral bone injury has been obtained by clinical MRI. Low-field MRI provides images helpful in the investigation of MCPJ/MTPJ region pathology in horses in the clinical setting but the greater resolution of high and ultra-field MR images has the potential to aid interpretation through a better understanding of MRI anatomy. Quantitative MRI could provide a non-invasive technique to determine tissue biochemical properties associated with the early onset of articular cartilage degenerative conditions such as osteoarthritis. So far, ultra-high field MRI has not been used in equine research and practice. However, recently 3T MRI has been introduced in equine hospitals in Europe and the US. The general objectives of this project, which utilised cadaver limbs, was to improve understanding of the MRI anatomy of the equine MCPJ/MTPJ region and to evaluate the use of MRI for the non-invasive, quantitative assessment of articular cartilage from the same region. The first specific objective was to describe the appearance of the normal anatomy of the equine MCPJ/MTPJ region, especially the SDFT & DDFT and DSLs, using high field (1.5T) and ultra high field (7T) MRI and to compare the images obtained with the two systems. The second objective was to determine the accuracy and precision of articular cartilage thickness measurements using 1.5T and 7T MRI and comparing the measurements with those made from histological sections of the MCPJ/MTPJ. The third objective was to measure T1 & T2 MRI sequence relaxation times for normal horse articular cartilage pre and post gadolinium contrast (dGEMRIC) administration and to determine their correlation with GAG concentration, including a description of topographical variation. The fourth objective was to compare sodium concentration in normal equine MCPJ/MTPJ articular cartilage measured using 7T MR imaging with a dual tuned quadrature 23Na/1H coil with the biochemical properties (sodium concentration determined by flame photometry and GAG concentration). The final objective was to evaluate MR sodium imaging for the assessment of enzymatically degraded equine cartilage. The findings demonstrated that 7T MRI produces high resolution images, which enable better evaluation of the hard and soft tissues of the equine MCPJ/MTPJ region than images from lower field MR systems and which permit accurate and precise articular cartilage thickness measurements to be made. Moreover, it was found that the dGEMRIC technique appears to provide a feasible quantitative tool for evaluating the articular cartilage properties. However, the quantitative parameters determined by the dGEMRIC method cannot fully characterise the biochemical properties of the cartilage. Moreover, delayed gadolinium-enhanced (dGEMRIC) techniques are time consuming, requiring relatively long incubation and scanning times. The measurement of T2 time is a very complex method. The work described in the last chapters demonstrated that sodium MRI was significantly correlated with the biochemical properties of the equine articular cartilage. Therefore the sodium MRI technique showed promise in imaging articular cartilage and providing useful information on the biochemical properties of the cartilage.

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Bracher, Verena D. "Equine endometritis." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306379.

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Siedek, Elizabeth. "Equine dendritic cells and immunity to equine Herpesvirus Type 1." Thesis, Royal Veterinary College (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286187.

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Watkins, Susan Beryl. "Equine blood rheology." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303177.

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8

Landgren, Emilia, and Sabina Wallman. "Hästavmaskningsmedels påverkan på miljö och välfärd." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-26001.

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Healthy, natural pastures is very valuable for biodiversity in the form of both plants and animals. An efficient use of pastures helps to preserve biodiversity, but grazing animals needs to be de-wormed to keep them healthy and to prevent harmful parasites spread on the pasture. The awareness about the environmental impact of the frequent use of deworming agents is low among the public. Some people are unaware that the absorption in horses of anthelmintics is incomplete, which make the circumstances about enviromental effect important to investigate further. The scientific evidence in this area is limited and more studies and trials are needed to deepen the knowledge about the effects of anthelmintics in the environment. Our report includes a compilation of studies conducted on anthelmintics and equine parasites, as well as an experiment which was conducted at the University of Halmstad biogaslaboratory April 2014. Anthelmintics have been shown to have negative impact on the manure ecosystem and especially against manure living fauna. Deworming routines has changed over the years as the equine industry has developed. Nevertheless, there’s still a lack of concrete approach to deworming.

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9

Baxi, Mohit K. "Molecular studies of equine herpesvirus 1 latency." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390272.

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10

Ganabadi, Shanthi. "Neurogenic components in equine and canine arthritis." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337147.

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11

Kelly, Louise. "The role of cytokines in equine joint diseases." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386803.

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12

Baker, Simon James. "The equine stomach : intragastic pH & gastric emptying." Thesis, Royal Veterinary College (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363043.

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13

Cochrane, Christine Ann. "An investigation into equine wound healing and sarcoid formation." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309890.

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14

Forhead, Alison Jane. "Equine hyperlipaemia : endocrine and metabolic basis of risk factors." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333560.

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15

Rickards, Karen Jane. "Neutrophil phosphodiesterase inhibition in equine chronic obstructive pulmonary disease." Thesis, Royal Veterinary College (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251618.

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16

McKelvie, Joanne. "The role of T-lymphocytes in equine sweet itch." Thesis, Royal Veterinary College (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300246.

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17

Tewari, Deepanker. "Immune response to equine herpesvirus-1 and it's glycoproteins." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360562.

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18

Cullinane, Anne A. "Characterization of the genome of equine herpesvirus 1 subtype 2." Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280852.

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MacEachern, Karen Elaine. "A study of equine pulmonary blood vessel function in vitro." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360283.

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20

Porter, J. H. "A structural and antigenic analysis of equine herpesvirus type 1." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384540.

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21

Frean, Stephen Philip. "Effects of anti-arthritic drugs on equine articular tissue metabolism." Thesis, Royal Veterinary College (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263731.

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Jarvis, Gavin Edward. "Endotoxaemia : the in vitro activation of equine platelets by endotoxin." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266364.

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Smith, Roger K. W. "The nature and role of non-collagenous proteins in equine tendon." Thesis, Royal Veterinary College (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284405.

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Clegg, Peter David. "Matrix metalloproteinase-2 and -9 and their inhibitors in equine joint disease." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263792.

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25

Lila, Mohd Azmi Mohd. "The immune response to equine herpesvirus type-1 (EHV-1) in a murine laboratory model." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319879.

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Awan, Aftab ur Rehman. "Studies on the pathogenesis of equine herpesvirus 1 and host responses to the infection in a mouse model." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387109.

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McCarthy, Helen Elizabeth. "A case-control study to investigate risk factors for equine grass sickness with a particular reference to the role of Clostridium botulinum." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250565.

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Wilsher, Sandra Ann. "Studies in equine reproduction." Thesis, University of Bedfordshire, 2009. http://hdl.handle.net/10547/134931.

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The papers put forward by the candidate represent a significant contribution to three main areas within the body of knowledge of equine reproduction. Namely, i) epidemiological surveys of the efficiency of Thoroughbred racing and breeding, ii) the morphology and functions of the equine placenta and, iii) embryo transfer in the horse. Two extensive surveys on reproductive efficiency of Thoroughbred mares and stallions at stud and factors associated with the failure of Thoroughbred horses to train and race demonstrated that increasing mare age is the greatest limiting factor to an otherwise high rate of fertility in English Thoroughbreds although a high incidence of early embryonic death remains a significant loss to the breeding industry. The racing wastage survey showed little change over the past 20 years in the percentage of 2- and 3-year-old horses that fail to run, the percentage that are never placed in a race and the number that suffer significant injury or illness during their racing careers. Radical and innovative changes to training methods are needed to overcome these problems. The morphology of the equine placenta was examined using gross measurements, stereological-techniques, vascular casting and immunohistochemistry and the findings related to fetal development and postnatal growth. Stereological measurements applied to term placentae established reference parameters such as surface area per unit volume of placental microcotyledons, the total microscopic area of contact between mother and fetus at the placental interface, and placental VI efficiency. Maternal age, parity, size, genotype and nutrition were all shown to alter placental morphology and, hence, pre- and postnatal fetal development. A novel pair of cervical forceps were designed and marketed to provide a simple and practical method for undertaking transcervical embryo transfer in the horse which enables inexperienced operators to transfer horse embryos successfully. These Wilsher Equine Embryo Transfer Forceps have won widespread acclaim and commercial application in the equine veterinary and scientific communities. A pharmacological method to extend donor-recipient synchrony was developed with both commercial and scientific application. Further work also showed the unique ability of the equine embryo to tolerate a very wide window of donor-recipient asynchrony and it provided a valuable research tool with which to study the relevant roles of the conceptus and uterine environment in regulating embryonic differentiation and fetal growth in the mare.

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Livesay, Georgia Jane. "Field and experimental approaches to the study of of influenza A/equine-2/Suffolk/89 (H3N8) virus : construction and characterisation of vaccina virus recombinants, and their use in immunoassays." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337874.

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30

Iqbal, Javid. "Investigations into the regulation of latency of equid herpesvirus 1." Thesis, Royal Veterinary College (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265298.

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31

Tearle, Jason Paul. "Pathogenesis of equid herpesvirus-1 infection in the male horse." Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363489.

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32

Sinclair, Robert. "Equid herpesvirus type-1 : antigenic analysis and diagnosis of infection using monoclonal antibodies." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292324.

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33

McGeorge, Gabrielle. "Effects of Strong Oxidants Present in Acer Spp. on Hemolysis Methemoglobin Production in Equine Erythrocytes." Otterbein University Honors Theses / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=otbnhonors1620459635176677.

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Dembek, Katarzyna Agnieszka. "Hypothalamic-pituitary-adrenal axis dysfunction in critically ill foals." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1479220019340433.

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35

Wynn, Michelle Arelia Ann. "Biology and Detection of Pregnanes During Late Gestation in the Mare." UKnowledge, 2017. http://uknowledge.uky.edu/gluck_etds/28.

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Progesterone in the mare declines to almost undetectable concentrations in late gestation. It’s metabolized into several pregnanes, some circulating at very high concentrations. Although the function of many pregnanes remains unclear, 5α-dihydroprogesterone and allopregnanolone are bioactive. Measurements of pregnanes in late gestation are typically by immunoassay, although results are confounded by cross-reactivity with related pregnanes. Conversely, liquid chromatography tandem mass spectrometry (LC-MS/MS) allows differentiation of individual pregnanes. The purposes of these studies were: 1) to evaluate the ability of a 5α-reductase inhibitor, dutasteride, to alter pregnane metabolism and pregnancy outcome, 2) to evaluate changes in target pregnanes in late gestation by LC-MS/MS in mares with ascending placentitis, and 3) compare immunoassay and LC-MS/MS detection of pregnanes in late gestation. Our findings suggest that dutasteride significantly altered pregnane metabolism without effects on pregnancy outcome. Pregnane measurement by LC-MS/MS resulted in a significant (p<0.05) differences in assay results, while correlation was observed between immunoassay measurements and actual progesterone concentrations by LC-MS/MS. These studies demonstrate the complexity of pregnane metabolism in late gestation in the mare and the necessity of LC-MS/MS to detect specific changes that immunoassays cannot differentiate.

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36

Taylor, Victoria A. "PHYSIOLOGICAL CHANGES ASSOCIATED WITH PREGNANT OR NONPREGNANT MARES GRAZING PASTURES OF ORCHARDGRASS-BLUEGRASS, KENTUCKY 31 TALL FESCUE INFECTED WITH EPICHLOË COENOPHIALA, OR KYFA9821 TALL FESCUE INFECTED WITH THE NOVEL ENDOPHYTE AR584." UKnowledge, 2017. https://uknowledge.uky.edu/gluck_etds/33.

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Kentucky 31 tall fescue (KY31) infected with the common toxic endophyte strains of Epichloё coenophiala produces toxic alkaloids that improve plant vigor, but cause numerous adverse effects in grazing animals. Researchers developed a variety of KY31 containing an alternative strain of E. coenophiala, termed novel endophyte (NE). Adverse health effects in mares have not been evaluated. Experiments in this thesis tested the hypothesis that the NE pasture does not cause adverse effects typically associated with KY31. Specific aims were to: 1) compare forage ergovaline concentrations between KY31 vs NE pastures; 2) evaluate palmar artery diameters in mares grazing KY31, NE, or orchardgrass-bluegrass (OGBG) pastures; 3) determine mare serum prolactin, estradiol, and progesterone concentrations associated with ingesting each pasture type over time; and 4) measure foaling outcomes, including percentage of live foals, foal birth weights, and foal growth rates. In 2015, six nonpregnant mares grazed KY31, six pregnant mares grazed NE and six pregnant mares grazed OGBG pastures. In 2016, eighteen mares were used; six mares grazed each pasture type. Study results showed that ergovaline did not appear to be produced by NE. Novel endophyte pasture did not have negative effects on palmar artery diameter, reproductive hormones, or foaling outcomes.

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Tadepalli, Sambasivarao. "Leukotoxin gene and activity in animal and human strains of Fusobacterium species." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/302.

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38

Lopes, Bruna Isabel Correia Pedras da Silva. "Applying Cell Therapies in Equine Chondroarticular Disorders - MSCs Characterization and Optimization." Master's thesis, 2020. https://hdl.handle.net/10216/126548.

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39

Borst, Luke B. "Investigations into a rationally designed modified live vaccine for equine strangles /." 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3362734.

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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.
Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3355. Adviser: Wanda M. Haschek-Hock. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

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Moorman, Valerie J. "Comparison of direct digital to conventional film-screen radiography in detection of experimentally created osseous lesions of equine third metacarpal bone." 2009. http://digital.library.okstate.edu/etd/Moorman_okstate_0664M_10304.pdf.

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Herrera-Hidalgo, Karla Elena. "Comparison of vitrification protocols in immature equine oocytes." Thesis, 2019. http://hdl.handle.net/1866/24703.

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La cryoconservation d'ovocytes est une méthode qui faciliterait la conservation du potentiel génétique chez la femelle et permettrait plus de flexibilité dans l'application des techniques de reproduction assistée chez les animaux domestiques et les espèces en voie de disparition. Chez le cheval, le taux de réussite de cette technique est faible comparée à celui obtenu chez d’autres espèces animales. Par conséquent, plus d’études seront nécessaires pour élucider les mécanismes spécifiques responsables du faible taux de succès après la cryopréservation. Le but de cette étude était d'évaluer l'effet de la vitrification d'ovocytes équins immatures sur leur taux de maturation, de clivage et le développement de blastocystes en utilisant un protocole de vitrification en trois étapes avec de l’ethylène glycol (EG) et du diméthylsulfoxyde (DMSO), ainsi que comparer l'effet des milieux hors congélation. Le protocole de vitrification utilisé dans la présente étude a été conçu en fonction des résultats obtenus au cours d’études préliminaires. Des ovocytes provenant de follicules immatures de juments ont été conservés pendant une nuit (14-18 heures) à température ambiante (~22⁰C) dans un milieu de maintien. Le lendemain, les ovocytes ont été dénudés et placés dans une solution de base (BS) composée de 20% de sérum de veau foetal (FBS) + M199/Hanks’ salts. Les ovocytes ont ensuite été répartis au hasard dans différents groupes : contrôle, vitrification et exposés aux agents cryoprotecteurs (CPA)-. Les ovocytes du groupe contrôle ont été immédiatement mis en maturation in vitro (IVM). Trois ovocytes ont été exposés à un protocole de vitrification en trois étapes décomposées en (1) solution de pré-vitrification (PVS) 1 (5% EG / 5 DMSO) 40s. (2) PVS 2 (10% EG / 10% DMSO) 40s et enfin, (3) solution de vitrification (VIT) (17,5% EG / 17,5% DMSO / 3 M saccharose) 10s. Le groupe vitrification est plongé dans l'azote liquide alors que les groupes CPA-exposés ont été exposés aux cryoprotecteurs mais n’ont pas été congelés. Les ovocytes ont ensuite été transférés sur un maillage en acier inoxydable stérile puis réchauffés à 42 ° C dans un BS pendant 5 min. Les ovocytes ont ensuite été soumis à l’IVM, fécondés par injection intracytoplasmique d’un spermatozoïde puis mis en culture dans le but de produire des embryons. Les différences en termes de maturation, de clivage et de taux de blastocystes entre les groupes ont été analysées par le test exact de Fisher. Le taux de maturation des deux groupes vitrification et CPA-exposés ne différait pas significativement avec le groupe contrôle. Aucun blastocyste n'a cependant été obtenu des groupes vitrification et CPA-exposés. Ces résultats ont montré que les ovocytes équins immatures peuvent maintenir une viabilité et une compétence méiotique après vitrification similaires à celles du groupe contrôle; de plus, l'exposition aux cryoprotecteurs n'a pas abouti à la formation de blastocystes en comparaison avec le groupe contrôle. Une étude plus approfondie sur la physiologie des ovocytes équins est nécessaire afin de pouvoir optimiser la production d’embryons.
Oocyte cryopreservation would facilitate the conservation of female genetic material and allow more flexibility in the application of assisted reproductive techniques in domestic animals and endangered species. The overall success rate of this technique in the horse is low compared with other species. Therefore, further research is required to elucidate the species-specific mechanisms responsible for poor survivability following vitrification. This study aimed to evaluate the effect on maturation rate, cleavage and blastocyst development of vitrified immature equine oocytes, using a three-step vitrification protocol with ethylene glycol (EG) and dimethyl sulfoxide (DMSO); and comparing the effect of media without freezing. The vitrification protocol was designed based on the results of preliminary experiments. Oocytes were recovered from immature follicles of live mares. Oocytes were held overnight at room temperature (14-24 hrs) in a holding medium. Oocytes were then denuded and placed in a base solution (BS) composed of 20% fetal bovine serum (FBS) + M199/Hanks’ salts. Oocytes were randomly allotted to control, vitrification, and cryoprotectant agents (CPAs)-exposed groups. Control oocytes were cultured directly for in-vitro maturation (IVM). Three oocytes were exposed to a three-step vitrification protocol composed of a pre-vitrification solution (PVS) 1 (5% EG/ 5% DMSO); PVS 2 (10% EG/ 10% DMSO) during 40s each; and finally vitrification solution (VS) (17.5% EG/ 17.5% DMSO/ 3 M sucrose), during 10s. All media were diluted in M199/Hanks’ salts + 20% FBS. Oocytes were then transferred to a 75-μm sterile stainless steel mesh. The oocytes were warmed at 42 °C in the BS for 5 minutes. Oocytes from the vitrified group were plunged into liquid nitrogen, while oocytes from CPA-exposed groups were only exposed to cryoprotectants. Oocytes were then subjected to IVM, fertilization and embryo culture. Fisher's Exact Test analyzed differences in maturation, cleavage and blastocyst rates between groups. The maturation rate of vitrified and CPA-exposed groups did not differ significantly from control oocytes. However, no blastocysts were obtained from CPA-exposed and vitrified groups. Vitrification and control groups showed that immature equine oocytes could maintain viability and meiotic competence; moreover, cryoprotectant exposure did not show any blastocyst formation as compared to control. Further investigation is necessary to understand the overall physiology of equine oocytes in order to optimize the developmental capacity of embryos.

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42

Aguiar, Christie. "Immune potential and differentiation of equine induced pluripotent stem cells (eiPSC)." Thèse, 2014. http://hdl.handle.net/1866/11943.

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Induced pluripotent stem cells (iPSC) have the capacity to self renew and differentiate into a myriad of cell types making them potential candidates for cell therapy and regenerative medicine. The goal of this thesis was to determine the characteristics of equine iPSC (eiPSC) that can be harnessed for potential use in veterinary regenerative medicine. Trauma to a horse’s limb often leads to the development of a chronic non-healing wound that lacks a keratinocyte cover, vital to healing. Thus, the overall hypothesis of this thesis was that eiPSC might offer a solution for providing wound coverage for such problematic wounds. Prior to considering eiPSC for clinical applications, their immunogenicity must be studied to ensure that the transplanted cells will be accepted and integrate into host tissues. The first objective of this thesis was to determine the immune response to eiPSC. To investigate the immunogenicity of eiPSC, the expression of major histocompatibility complex (MHC) molecules by the selected lines was determined, then the cells were used in an intradermal transplantation model developed for this study. While transplantation of allogeneic, undifferentiated eiPSC elicited a moderate cellular response in experimental horses, it did not cause acute rejection. This strategy enabled the selection of weakly immunogenic eiPSC lines for subsequent differentiation into lineages of therapeutic importance. Equine iPSC offer a potential solution to deficient epithelial coverage by providing a keratinocyte graft with the ability to differentiate into other accessory structures of the epidermis. The second objective of this thesis was to develop a protocol for the differentiation of eiPSC into a keratinocyte lineage. The protocol was shown to be highly efficient at inducing the anticipated phenotype within 30 days. Indeed, the eiPSC derived vi keratinocytes (eiPSC-KC) showed both morphologic and functional characteristics of primary equine keratinocytes (PEK). Moreover, the proliferative capacity of eiPSC-KC was superior while the migratory capacity, measured as the ability to epithelialize in vitro wounds, was comparable to that of PEK, suggesting exciting potential for grafting onto in vivo wound models. In conclusion, equine iPSC-derived keratinocytes exhibit features that are promising to the development of a stem cell-based skin construct with the potential to fully regenerate lost or damaged skin in horses. However, since eiPSC do not fully escape immune surveillance despite low MHC expression, strategies to improve engraftment of iPSC derivatives must be pursued.
Les cellules souches pluripotentes induites (iPSC) ont la capacité de s'auto renouveler et de se différencier en une myriade de types cellulaires, ce qui en fait des outils intéressants pour la thérapie cellulaire et la médecine régénérative. Le but de cette thèse était de déterminer les caractéristiques des iPSC équines (eiPSC) qui peuvent être exploitées pour l'usage potentiel en médecine régénérative vétérinaire. Chez le cheval, une plaie cutanée est souvent cicatrisée par seconde intention et est sujette à de nombreuses complications lorsque située sur le membre, notamment une épithélialisation lente. Ainsi, l'hypothèse globale de cette thèse était que les eiPSC pourraient offrir une solution novatrice de couverture pour de telles blessures. Avant d'envisager l’utilisation d'eiPSC à des fins cliniques, leur immunogénicité doit être étudiée afin de s'assurer que les cellules transplantées seront acceptées et intégrées dans les tissus du receveur. Le premier objectif de cette thèse était de définir la réponse immunitaire suscitée par les eiPSC. Afin d'étudier l'immunogénicité d'eiPSC, l'expression de molécules du complexe majeur d’histocompatibilité (MHC) des lignes choisies a été déterminée, puis les cellules ont été utilisées dans un modèle de transplantation intradermique développé pour cette étude. Bien que la transplantation allogénique d'eiPSC non différenciées ait induit une réponse cellulaire modérée chez les chevaux d'expérimentation, elle n'a pas provoqué de rejet. Cette stratégie a permis la sélection de lignées d'eiPSC faiblement immunogènes pour la différenciation ultérieure en des lignées d'importance thérapeutique. Les eiPSC représentent une solution intéressante et qui, par l’entremise du développement d’une lignée de kératinocytes, pourraient servir à la création d’une greffe ayant la capacité de former non seulement l’épithélium manquant mais aussi d'autres structures accessoires de l'épiderme. Le deuxième objectif de cette thèse était donc de iv développer un protocole pour la différentiation des eiPSC en lignée de kératinocytes. Un protocole visant cette différenciation fut ainsi développé et ce dernier a démontré une grande efficacité à produire le phénotype attendu dans une période de 30 jours. En effet, les kératinocytes dérivés d'eiPSC (eiPSC-KC) ont montré des caractéristiques morphologiques et fonctionnelles des kératinocytes primaires équins (PEK). En outre, la capacité de prolifération d'eiPSC-KC est supérieure tandis que la capacité migratoire, mesurée comme l'aptitude à cicatriser les plaies in vitro, est comparable à celle du PEK. En conclusion, les eiPSC-KC ont des caractéristiques intéressantes pour le développement d'un substitut cutané à base de cellules souches, ayant le potentiel de régénérer la peau perdue lors de trauma ou de maladie, chez le cheval. Cependant, parce que les eiPSC n'échappent pas totalement à la surveillance immunitaire, malgré une faible expression du MHC, des stratégies pour améliorer la prise de greffe eiPSC-KC doivent être élaborées.

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Poirier, Mikhael. "Effets de la reprogrammation sur le gène empreinté H19 chez les équins." Thèse, 2014. http://hdl.handle.net/1866/12406.

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Lors de la fécondation, le génome subit des transformations épigénétiques qui vont guider le développement et le phénotype de l’embryon. L'avènement des techniques de reprogrammation cellulaire, permettant la dédifférenciation d'une cellule somatique adulte, ouvre la porte à de nouvelles thérapies régénératives. Par exemple, les procédures de transfert nucléaire de cellules somatique (SCNT) ainsi que la pluripotence par induction (IP) visent à reprogrammer une cellule somatique adulte différentiée à un état pluripotent similaire à celui trouvé durant la fécondation chez l'embryon sans en impacter l'expression génique vitale au fonctionnement cellulaire. Cependant, la reprogrammation partielle est souvent associée à une mauvaise méthylation de séquences géniques responsables de la régulation des empreintes géniques. Ces gènes, étudiés chez la souris, le bovin et l'humain, sont exprimés de manière monoallélique, parent spécifique et sont vitaux pour le développement embryonnaire. Ainsi, nous avons voulu définir le statut épigénétique du gène empreinté H19 chez l'équin, autant chez le gamètes que les embryons dérivés de manière in vivo, SCNT ainsi que les cellules pluripotentes induites (iPSC). Une région contrôle empreinté (ICR) riche en îlots CpG a été observée en amont du promoteur. Couplé avec une analyse de transcrit parent spécifique du gène H19, nous avons confirmé que l'empreinte du gène H19 suit le modèle insulaire décrit chez les autres mammifères étudiés et résiste à la reprogrammation induite par SCNT ou IP. La déméthylation partielle de l'ICR observée chez certains échantillons reprogrammés n'était pas suffisante pour induire une expression biallélique, suggérant un contrôle des empreintes chez les équins durant la reprogrammation.
After fertilization, the animal genome undergoes a complex epigenetic remodeling that dictates the growth and phenotypic signature of the animal. The development of reprogramming methods using adult differentiated cells as the primordial genetic source has opened the door to new regenerative therapies for animals. Somatic cell nuclear transfer (SCNT) and induced pluripotency are two techniques which aim to reprogram a cell from its adult differentiated state to an embryonic-like pluripotency level, without impairing the expression of genes vital for the cellular function. Albeit promising, the mechanisms involved in these techniques remain only moderately understood. Partial reprogramming is frequently associated with irregular methylation of DNA sequences responsible for imprint regulation. These imprinted genes, mostly studied in rodents, cattle and humans, are expressed in a monoallelic parent-specific fashion and are vital for embryo growth. Hence, we aim to define the equine H19 imprinting control region (ICR) in gametes, in vivo and in SCNT derived embryos, as well as in induced pluripotent stem cells (iPSC). A CpG rich ICR was characterized upstream of the promotor using bisulfite treated DNA sequencing. Coupled with parent-specific gene expression analysis, we confirmed that the imprinted gene H19 is resistant to cellular reprogramming, and that partial demethylation of its ICR does not result in biallelic expression, suggesting that equine species have rigorous imprint maintenance during cellular reprogramming.

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Dubuc, Julia. "Caractérisation des déchirures méniscales équines et de leur relation avec l’ostéoarthrose fémorotibiale." Thèse, 2018. http://hdl.handle.net/1866/22612.

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Bullone, Michela. "Reversibility of airway remodeling in equine asthma : contribution of anti-inflammatory and bronchodilator therapies." Thèse, 2016. http://hdl.handle.net/1866/18381.

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L’asthme bronchique est caractérisé par un remodelage et une inflammation des voies aériennes. La masse du muscle lisse ainsi que la déposition de matrice extracellulaire sont augmentées dans la paroi des bronches asthmatiques, ce qui contribue à l’obstruction respiratoire. Peu d’études ont évalué les effets des traitements utilisés dans l’asthme sur le remodelage bronchique, et surtout peu de données sont disponibles concernant les effets sur le muscle lisse. La combinaison de corticostéroïdes et de β2-agonistes à longue durée d’action administrée par inhalation permet de mieux contrôler les crises d’asthme par rapport à la monothérapie avec des médicaments corticostéroïdes. Cependant, l’action spécifique de la combinaison sur le remodelage et sur l’inflammation des bronches périphériques n’est pas décrite. Surtout, il reste à clarifier si l’administration de la combinaison est avantageuse par rapport à la monothérapie corticostéroïde. La plupart des études réalisées chez l’homme utilisent des tissus bronchiques obtenus par biopsie endobronchique, qui ne sont pas représentatifs du processus pathologique affectant les voies respiratoires périphériques. Leur inaccessibilité par des méthodes non invasives est la raison pour laquelle si peu de données existent sur la pathophysiologie des voies périphériques chez les patients asthmatiques. L’asthme équin, aussi connu comme « le souffle », est une pathologie obstructive des chevaux adultes considérée comme un modèle animal d’asthme humain. Elle est caractérisée par un remodelage des bronches périphériques et par une inflammation bronchoalvéolaire de type neutrophilique. En étudiant le modèle équin, cette thèse a évalué la contribution des médicaments corticostéroïdes et de β2-agonistes à longue durée d’action, administrée comme monothérapies ou en combinaison, sur la réversibilité du remodelage et de l’inflammation de voies aériennes dans l’asthme bronchique. A cette fin, nous avons d’abord optimisé et validé l’application de la biopsie endobronchique et de l’échographie endobronchique chez le cheval adulte. Nos résultats indiquent que les échantillons obtenus par biopsie endobronchique sont inadéquats pour l’évaluation quantitative de la masse du muscle lisse chez le cheval. Cependant, ils permettent d’étudier les changements quantitatifs des structures épithéliales et de la lamina propria, ainsi que les aspects qualitatifs du muscle lisse. L’échographie endobronchique, quant à elle, permet d'estimer la masse du muscle lisse bronchique, et ce, chez des chevaux sains et chez des chevaux asthmatiques. Cette thèse démontre aussi que qu’un traitement de 12 semaines avec des corticostéroïdes induit une diminution significative de la masse du muscle lisse périphérique, qui n’est pas amélioré davantage par l’administration concomitante d’un β2-agoniste à longue durée d’action. Cette diminution est toutefois incomplète. Un effet positif et synergique de la combinaison a également été observé au niveau de la déposition de matrice extracellulaire. La combinaison a produit une diminution significative de la quantité de matrices déposées dans la lamina propria et dans la couche du muscle lisse dans les bronches centrales, alors que l’effet été limité à la couche du muscle lisse dans les bronches périphériques. La combinaison n’améliore pas le contrôle de l’inflammation bronchique ni bronchiolaire par rapport aux monothérapies ; cependant, elle diminue la neutrophilie bronchoalvéolaire de façon synergique.
Airway remodeling and inflammation are the hallmarks of asthma. Both airway smooth muscle (ASM) mass and extracellular matrix (ECM) deposition are increased in the central and peripheral airways of asthmatic patients, which contribute to airway obstruction. Few studies have investigated the ability of current asthma medications to reverse airway remodeling, especially the increased ASM mass. Inhaled corticosteroids (ICS) and long-acting β2-agonist combinations (ICS/LABA) are more effective than ICS monotherapy to control asthma exacerbations. However, their efficacy at modifying bronchial inflammation and remodeling at the peripheral level of the lung is not well-described. In fact, most work has been performed using endobronchial biopsy samples obtained from asthmatic subjects, which completely disregard the alterations occurring in peripheral airways. Ethical considerations limit the possibility of biopsying the peripheral airways in humans due to the invasiveness of the procedure. Equine asthma, or heaves, is a naturally-occurring disease of adult horses and a recognized animal model of human asthma characterized by neutrophilic inflammation as well as ASM and ECM remodeling of peripheral airways. This thesis has assessed the contribution of ICS and LABA, alone or combined, to the reversal of remodeling and inflammation in central and peripheral airways using the equine asthma model. To attain this goal, we have first optimized and validated the application of endobronchial biopsy and endobronchial ultrasound (EBUS) in the equine species. EBUS reliably estimates the bronchial ASM. Subsequently, asthmatic horses with ongoing airway remodeling and inflammation were treated with ICS, LABA, ICS/LABA, or antigen avoidance. Lung function, airway remodeling and inflammation were then assessed weekly for 3 months. Our results demonstrated a 30% decrease of peripheral ASM remodeling attained with ICS and ICS/LABA pharmacological treatment. A decrease of a similar magnitude of peripheral ASM was previously reported after 6 and 12 months of ICS monotherapy and antigen avoidance, respectively. A synergistic effect of ICS/LABA was observed on ECM deposition and airway lumen neutrophils. ICS/LABA decreased the ECM fraction of the ASM layer both peripherally and centrally, while the same effect on the lamina propria was observed only in central airways. Both ICS/LABA and ICS monotherapy decreased submucosal inflammation in central airways, while only ICS/LABA and antigen avoidance decreased bronchoalveolar neutrophilia. In conclusion, our results suggest that the enhanced therapeutic effect of ICS/LABA over ICS monotherapy in asthmatic horses was associated with a reduction of ECM deposition, mainly observed within the large airways, and possibly also with a decreased airway neutrophilia. However, ICS/LABA did not provide additional benefit to ICS monotherapy in terms of peripheral ASM remodeling as both induce a 30% decrease of the ASM mass in 3 months.

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46

Anne-Archard, Nicolas. "Étude de la microarchitecture trabéculaire du sillon parasagittal et du condyle du métacarpe distal chez le cheval de course, à la naissance et chez l’adulte." Thèse, 2016. http://hdl.handle.net/1866/18624.

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47

Pouyet, Morgane. "Mise au point d’une technique de sinusoscopie peu invasive chez le cheval." Thesis, 2018. http://hdl.handle.net/1866/22609.

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Les affections sinusales sont la première cause de jetage nasal unilatéral chez les chevaux. Cependant, la complexité anatomique de la région rend le diagnostic difficile avec la radiologie et l’endoscopie, et l’utilisation des techniques diagnostiques plus avancées comme la tomodensitométrie est souvent limitée par le manque de disponibilité et les coûts. Par conséquent, la sinusoscopie est souvent la technique disponible avec le meilleur taux diagnostic (70%) mais demeure invasive (trépanation de 10 à 15 mm) et peu pratique dans certains cas. Notre hypothèse est que le développement d’une technique de sinusoscopie peu invasive (TSPI), réalisée par une mini-trépanation avec une aiguille 14G (2 mm de diamètre), combinée à l’utilisation d’un nouvel endoscope flexible de 2 mm de diamètre, peut permettre d’obtenir une évaluation exhaustive des différents sinus paranasaux. Durant les deux premières phases du projet, réalisées sur des cadavres, les repères anatomiques pour réaliser une mini-trépanation des différents sinus ont été déterminés puis la visualisation des différents compartiments sinusaux a été évaluée en attribuant un score pour chaque structure sinusale. Dans une troisième phase, la TSPI a été appliquée sur des chevaux debout sous sédation afin de déterminer la faisabilité et les éventuelles complications chez des chevaux vivants. Les repères déterminés durant la phase 1 ont permis une exploration exhaustive et satisfaisante des sinus durant les deux phases suivantes. L’ensemble des chevaux a bien toléré la procédure et aucune complication sérieuse n’a été rapportée. La technique développée est facile à réaliser et peu faciliter le diagnostic des affections sinusales par tous les vétérinaires spécialistes ou non.
Paranasal sinus disease is the most common cause of unilateral nasal discharge in horses. However, achieving a definitive diagnosis using radiology and endoscopy is difficult due to the complex anatomy of the sinuses, and the use of computed tomography (gold standard) is often limited due to its cost and low availability. Consequently, sinoscopy is often the available diagnostic technique with the highest diagnostic rate (70%) but it remains invasive (10 to 15 mm trepanation) and unpractical in some cases. Our hypothesis is that the development of a minimally invasive sinoscopic technique (MIST), performed through a mini-trepanation with a 14G needle (2 mm trephination) and combined with the use of a novel flexible 2mm diameter endoscope, can allow an exhaustive evaluation of the paranasal sinuses. During the first two cadaveric phases of the project, we determined the exact anatomic landmarks to perform the mini-trepanation in the different sinuses, and the visualization of the different sinus compartments was assessed by attributing a score to each sinusal structure. In the last phase of the study, the MIST was performed on standing sedated horses to determine the feasibility and possible complications associated to the technique. The landmarks determined in the first phase allowed a thorough evaluation of the sinuses in the following phases. The horses tolerated well the procedure and no serious complications were reported. The technique developed during this study is easy to perform and could facilitate the diagnosis of paranasal sinus diseases for all veterinarians specialized or not.

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Fillion-Bertrand, Gabrielle. "Le microbiome bactérien pulmonaire dans l'asthme équin." Thèse, 2016. http://hdl.handle.net/1866/19163.

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Le microbiome bactérien constitue l’ensemble des bactéries retrouvées au sein d’un espace. Le rôle du microbiome pulmonaire dans l’asthme est mal défini, mais il est maintenant établi que celui de patients asthmatiques diffère de celui d’individus sains. Cependant, l’influence des conditions environnementales et de la médication sur le microbiome pulmonaire est méconnue et leurs effets difficiles à contrôler chez l’humain. De plus, la stabilité du microbiome dans le temps demeure controversée. L’hypothèse de l’étude est que les microbiomes pulmonaire, nasal et oral de chevaux non-médicamentés varient avec l’environnement et que le statut asthmatique affecte principalement le microbiome pulmonaire. Six chevaux atteints d’asthme équin sévère et 6 chevaux sains ont été gardés dans 3 environnements distincts (exposition antigénique faible, modérée et élevée). Dans chaque environnement, la fonction pulmonaire a été évaluée et des lavages bronchoalvéolaires (LBA), oraux et nasals ont été prélevés. La région V4 du gène de l’ARN ribosomal 16S a été séquencée (Illumina MiSeq 4) et analysée à l’aide du logiciel Mothur et du progiciel Vegan dans R. Les communautés bactériennes pulmonaires, orales et nasales sont fortement regroupées par conditions environnementales et l’effet de l’environnement est plus marqué chez les chevaux sains. Le microbiome pulmonaire des chevaux asthmatiques diffère de celui des chevaux sains au niveau taxonomique de la famille, avec une tendance à une surreprésentation des Pasteurellaceae, contrairement aux microbiomes nasal et oral qui ne sont pas différents entre les deux groupes. Les familles bactériennes Neisseriaceae, Lachnospiraceae et Bacteroidaceae, dont certaines espèces sont potentiellement pathogènes, ont été seulement retrouvées dans les LBAs de chevaux asthmatiques. Cette étude montre que les microbiomes bactériens pulmonaires des chevaux sains et asthmatiques ne recevant pas de médication sont différents et varient selon le niveau d’exposition antigénique. Cette différence étant présente principalement lorsque les chevaux asthmatiques ont une inflammation pulmonaire suggère que le microbiome pulmonaire altéré dans l’asthme n’est pas inhérent, mais coïncide avec l’inflammation pulmonaire. Le rôle du microbiome dans la perpétuation de l’inflammation reste à investiguer.
Bacterial microbiome is defined as the whole bacterial population found within a space. The role of the pulmonary microbiome in asthma is poorly defined, but it is now well established that the one of asthmatic patients differs from that of healthy individuals. However, the influence of environmental conditions and medication on pulmonary microbiome is poorly known and effects difficult to control in humans. Moreover, microbiome stability over time remains controversial. The hypothesis of this study is that the pulmonary, nasal and oral microbiomes of unmedicated horses vary with the environment and that asthmatic status does affect the pulmonary microbiome. Six horses with severe equine asthma and 6 healthy horses were kept in 3 distinct environments (low, moderate and high antigen exposure). In each environment, pulmonary function has been evaluated and bronchoalveolar lavages (BALs), nasal and oral washes were collected. The V4 region of the 16S rRNA gene was sequenced (Illumina MiSeq 4) and analyzed using the Mothur software and the Vegan package in R. Pulmonary, oral and nasal bacterial communities are strongly grouped by environmental conditions and the effect of the environment is more pronounced in healthy horses. The pulmonary microbiome of asthmatic horses differs from that of healthy horses at the family level of taxonomic designation, with a tendency towards an overrepresentation of Pasteurellaceae, unlike nasal and oral microbiomes which are not different between the two groups. The bacterial families Neisseriaceae, Lachnospiraceae and Bacteroidaceae with pathogenic potential were only found in the BALs of asthmatic horses. This study shows that the lung bacterial microbiomes of healthy and asthmatic horses receiving no medication are different and vary accordingly to the antigenic exposure level. This difference is present mainly when asthmatic horses have a strong pulmonary inflammation which suggest that the altered pulmonary microbiome is not inherent but coincident with pulmonary inflammation. Its role in the perpetuation of inflammation remains to be investigated.

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Di, Pietro Rebecca. "Development of a protocol with concentrated bacteria for fecal microbiota transplantation and impact on the equine fecal microbiota after antibiotic-induced dysbiosis." Thesis, 2020. http://hdl.handle.net/1866/24704.

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Le microbiote intestinal équin joue un rôle important dans le maintien de la santé de l'hôte. Le microbiote intestinal est composé de nombreux micro-organismes tels que les bactéries, les virus, les champignons et les archées. Cependant, la majorité de ces cellules microbiennes sont bactériennes, et par conséquent, de nombreuses études, y compris la présente, se concentrent sur l'exploration des communautés bactériennes dans l'intestin. Un déséquilibre du microbiote intestinal, appelé dysbiose, a été observé dans plusieurs conditions, telles que la colite, après l’administration d'antibiotiques ou la modification du régime alimentaire. La restauration du microbiote peut être effectuée par la transplantation de microbiote fécal (FMT). Des études utilisant les recommandations actuelles pour la FMT ont montré une récupération clinique chez les chevaux souffrant de diarrhée, mais le microbiote reste largement inchangé après la FMT et aucune étude randomisée avec contrôle placébo n'a été réalisée. Les hypothèses de ce projet étaient que le traitement avec une FMT concentrée corrigera la dysbiose plus rapidement qu’une FMT conventionnelle et le véhicule, et que le microbiote intestinal des chevaux traités avec une FMT concentrée ressemblera au microbiote intestinal du cheval donneur. L'objectif de ce projet était de développer un protocole pour améliorer la FMT chez les chevaux, en augmentant la concentration de bactéries présentes dans les selles du donneur par centrifugation, et de le tester chez les chevaux atteints de dysbiose intestinale induite par les antibiotiques. L'antibiotique triméthoprime sulfadiazine (TMS) a été administré à neuf chevaux pour induire une dysbiose intestinale. Les chevaux ont été séparés en trois groupes: les chevaux recevant une FMT concentrée (cFMT, n = 3); les chevaux recevant la FMT fraîche (fFMT), selon les recommandations actuelles (n = 3); et les chevaux recevant un véhicule (VEH) avec 10% de glycérol dans une solution saline à 0,9% (n=3). Des échantillons fécaux ont été prélevés avant et après l'administration du TMS, ainsi qu'avant, pendant et après la transplantation. Le séquençage a été réalisé à l'aide de la plateforme Illumina MiSeq et les données analysées à l'aide du logiciel Mothur. Tel qu’attendu, l'antibiotique TMS a significativement diminué la richesse microbienne chez tous les chevaux. De manière inattendue, la composition des suspensions fécales des donneurs cFMT et fFMT était significativement différente de la composition de base des receveurs cFMT et fFMT, respectivement. La composition du microbiote des chevaux ayant reçu une transplantation fécale (concentrée ou non) était significativement différente après la transplantation, alors que ce n’était pas le cas chez les chevaux ayant reçu le véhicule. En outre, l’abondance relative de Escherichia était significativement plus élevée dans les suspensions fécales du donneur cFMT par rapport aux suspensions fécales du donneur fFMT. Les principales limites de ce projet sont la petite taille des groupes et l'exposition des selles des donneurs à l'oxygène et à la congélation-décongélation. En outre, le modèle de dysbiose peut ne pas être optimal pour tester l'efficacité de la FMT, et des études réalisant la FMT chez les chevaux souffrant de diarrhée sont nécessaire. Cette étude a contribué à la recherche de nouvelles approches pour améliorer la FMT chez les chevaux. Le faible effet mesuré avec les deux protocoles de FMT et l’augmentation de Escherichia démontre que les protocoles actuels doivent être optimisés avant de pouvoir recommander la FMT pour traiter et prévenir la dysbiose chez les chevaux.
The equine gut microbiota plays an important role in maintaining the health of the host. The gut microbiota is composed of many microorganisms such as bacteria, viruses, fungi, and archaea. However, the majority of these microbial cells are bacterial cells, and consequently, many studies, including the present one, focus on exploring bacterial communities in the gut. An imbalance of the gut microbiota, termed dysbiosis, has been observed in several conditions such as colitis, colic, after antibiotic administration, or diet modification. Restoration of the gut to a healthy state can be performed through fecal microbiota transplantation (FMT). Studies using current recommendations for FMT have shown clinical recovery in horses with diarrhea, but the microbiota remains largely unchanged after FMT and no controlled studies have been performed. The hypotheses of this project were that treatment with concentrated FMT will correct dysbiosis faster than conventional FMT and the vehicle, and that the gut microbiota of horses treated with concentrated FMT will resemble the gut microbiota of the donor. The objective of this project was to develop an improved protocol for FMT in horses, by increasing the concentration of bacteria found in the donor stool using centrifugation, and to test it in horses with antibiotic-induced intestinal dysbiosis. The antibiotic trimethoprim sulfadiazine (TMS) was administered to nine horses to induce intestinal dysbiosis. Horses were separated into three groups: horses receiving concentrated FMT (cFMT) (n=3); horses receiving fresh FMT (fFMT), as per current recommendations (n=3); horses receiving a vehicle (VEH) with 10% glycerol in 0.9% saline (n=3). Fecal samples were collected before and after antibiotic administration, as well as before, during, and after transplantation. Sequencing was performed using the Illumina MiSeq platform and data analysed using the software Mothur. As expected, the antibiotic TMS significantly decreased the richness in all horses (P < 0.05). Unexpectedly, the membership of the cFMT and fFMT donor fecal suspensions was significantly different from cFMT and fFMT recipients’ baseline membership, respectively. The membership of the cFMT and fFMT recipient horses was significantly different after transplantation, while the vehicle recipients were not. In addition, the Escherichia genus was found in significantly higher relative abundances in the cFMT donor fecal suspensions when compared to the fFMT donor fecal suspensions. The main limitations of this study are the small sample size and exposure of cFMT donor stool to oxygen and freeze-thawing. In addition, the dysbiosis model may not be optimal to test the efficacy of FMT, and studies performing FMT in horses with diarrhea are warranted. This study contributed to the search for novel approaches to improve FMT in horses. The weak effect of both FMT protocols on the gut microbiota and the increase in Escherichia suggest that further clinical studies are needed before FMT can be recommended to treat and prevent dysbiosis in horses.

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Dubuc, Valérie. "Développement d’une méthode informatique appliquée à la quantification immunohistochimique du mastocyte et du macrophage M1 et M2 lors de la guérison cutanée chez le cheval." Thèse, 2018. http://hdl.handle.net/1866/21866.

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Dissertations / Theses on the topic 'Equine veterinary science'

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