Life Sciences Commons^™

Use Of Molecular Genetics To Investigate Population Structure And Swayback In Horses, Navid Yousefimashouf

Theses and Dissertations--Veterinary Science

The present research incorporated molecular genetic methods to 1) investigate the genetic basis of Juvenile Onset Lordosis or Swayback in the American Saddlebred horses; and 2) conduct a population genetic study to compare the Persian Kurdish, Persian Arabian and American Thoroughbred horse populations.

Juvenile-onset lordosis, or swayback, is a condition in horses where the conformational topline back curvature drops significantly within the first two years of life. The trait has a higher prevalence in Saddlebreds (5%). Prior research on them quantified the trait using a Measurement of Back Contour (MBC), defining an MBC of >7.0 centimeters as swayback, and8.0) MBC …

Effects Of High-Speed Training On Messenger Rna Expression In Two-Year-Old Thoroughbred Racehorses, Mackenzie Grace Johnson

Theses and Dissertations--Veterinary Science

Accumulating high-speed exercise has been identified as a significant risk factor for catastrophic injuries in racing Thoroughbreds. Injuries, regardless of severity, are a main cause of withdrawal from the racing industry, raising animal welfare concerns and resulting in significant economic losses. While most of the current literature focuses on catastrophic injuries incurred during racing rather than training, the present study aims to help fill this gap as well as discuss the associated risk factors. The evaluation of messenger RNA (mRNA) expression changes provides an efficient and straightforward approach to identifying horses at risk for catastrophic injury. While alternative injury risk …

Molecular Genetic Studies Of Horses, Especially With Reference To Aggrecan And Dwarfism, John Edmund Eberth

Theses and Dissertations--Veterinary Science

This work consists of studies on dwarfism in Miniature horses and a study on breakdowns in Thoroughbreds in relation to gene aggrecan. A correction of the description and designation of D3 dwarf variant in aggrecan (ACAN) from the master’s thesis Chondrodysplasia-like dwarfism in the Miniature horse (2013). Commercial sequencing showed previous sequencing reads presented an artifact and not a single base deletion. Analysis showed a single base missense mutation in exon 8 identified as D3* was the actual cause. Multiple alleles of ACAN associated with chondrodysplastic dwarfism in Miniature horses by Eberth et al. (2018), corrected the …

Dissecting The Role Of Actin-Myosin Motor And Calcium – Based Organelle Secretion In Motility Of Sarcocystis Neurona, Parul Suri

Theses and Dissertations--Veterinary Science

Sarcocystis neurona is a protozoan parasite that causes a rare neurological disorder in horses called Equine Protozoal Myeloencephalitis (EPM). Apicomplexa use actin-myosin based motor and organelle secretion to interact with the host cell and invade it. Despite the importance of motility and invasion-needed factors, the mechanisms by which S. neurona employs host cell association strategies to interact remains largely undefined. To address this knowledge gap, we hypothesize that just like other Apicomplexa, S. neurona utilizes actin polymerization for substrate-dependent gliding. Moreover, we also hypothesize that micronemes of S. neurona secrete proteins that are calcium-dependent. Based on previous studies in T. …

The Microbiome Of The Equine Roundworm, Parascaris Spp., Jennifer Lynn Cain

Theses and Dissertations--Veterinary Science

Parasitic nematodes, including the large roundworms colloquially known as ascarids, affect the health and well-being of livestock animals worldwide. The equine ascarid, Parascaris spp., was the first ascarid parasite to develop wide-spread anthelmintic drug resistance, with other species slowly following suit. There are no new classes of anthelmintics currently in development, and a solution to the ever-increasing prevalence of resistance is desperately needed. The microbiome has been shown to be an important factor in the fitness and health of many organisms and changes to microbiome composition have been associated with a plethora of diseases. The microbiome is also important to …

Effects Of Season And Nutrition On Insulinemic Responses In Insulin Dysregulated Horses, Erica Lyn Macon

Theses and Dissertations--Veterinary Science

Insulin dysregulation (ID) is the main risk factor for the development of hyperinsulinemia-associated laminitis (HAL). ID in the equid has been extensively researched; however, recommendations for diagnosing and managing ID horses have originated from work completed in other models, such as the ID pony and healthy horse. Therefore, our overall objective was to improve current diagnostic tools and nutritional management strategies by investigating the effect of season, the fed and fasted state on the oral sugar test (OST) and dietary nutrient content on insulinemic responses in the ID horse. To address this, four main objectives with three specific aims were …

Muscle Mass And Immune Function In The Senior Horse, Alisa Christina Herbst

Theses and Dissertations--Veterinary Science

Senior horses (≥ 15 years) represent up to one-third of the global equine population, and the proportion of old horses (≥ 20 years) in the U.S. has been steadily increasing. Aging is associated with a loss of skeletal muscle mass in horses, and while age-related muscle loss is comparingly well characterized in humans, little is currently known concerning underlying mechanisms, adverse outcomes, or the prevalence of low muscle mass in senior horses. One factor proposed to play a role in the development of age-related muscle atrophy in humans is inflamm-aging, a low-grade inflammation that affects elderly people and that has …

Comparative Chondrogenesis Of Interzone And Anlagen Cells In Equine Skeletal Development, Chanhee Mok

Theses and Dissertations--Veterinary Science

At the presumptive sites of future synovial joints during mammalian skeletogenesis, articular cartilage develops from interzone located between the cartilaginous anlagen of bones. Thus, two types of cartilaginous tissues differentiate in close proximity. While anlagen cartilage is transient, progressing through endochondral ossification to form bones, articular cartilage is stable and functions throughout life to facilitate both low friction movement and load distribution. Despite important life-long functional properties, articular cartilage has a very limited intrinsic ability to repair structural defects. On the other hand, structural lesions in bones generally heal well by forming a cartilaginous callus and recapitulating endochondral ossification to …

Donor Age Effects On The Proliferative And Chondrogenic/Osteogenic Differentiation Performance Of Equine Bone Marrow- And Adipose Tissue Derived Mesenchymal Stem Cells In Culture, Jasmin Bagge

Theses and Dissertations--Veterinary Science

Orthopedic injuries are a major cause of lameness and morbidity in horses. Bone marrow (BM)- and adipose tissue (AT) derived mesenchymal stem cells (MSCs) have shown potential to facilitate the repair of orthopedic injuries and are being used increasingly in veterinary clinics. Presently, the use of MSCs as a therapy for equine patients is most commonly applied as autologous transplants, using BM- and AT-MSCs harvested from the patient shortly after the time of injury. Cell-based therapies are therefore delayed to enable primary cell numbers to be expanded in culture. Of concern, however, are human and rodent studies that have shown …

Evaluation Of Rhodococcus Equi Susceptibility To Silver Nanoparticle Antimicrobials, Elizabeth Boudaher

Theses and Dissertations--Veterinary Science

Rhodococcus equi is a significant cause of pneumonia in foals and immunocompromised humans. Antimicrobial resistance among R. equi isolates has developed as a consequence of inappropriate stewardship and bacterial evolution, leading to an increased rate of treatment failures that typically result in foal fatality. In the current study, we evaluated the efficacy of antimicrobial silver nanoparticle (AgNP) complexes in controlling R. equi growth. Previous studies characterizing AgNP-induced antibacterial effects in other Gram-positive pathogens led us to hypothesize that silver nanoparticle antimicrobials impact R. equi viability and intracellular replication. We therefore investigated the effect of silver nanoparticle complexes on R. equi …

Development And Evaluation Of Nonradioactive Methods For Monitoring T Lymphocyte Response To Equine Arteritis Virus (Eav) In Horses, Annet Kyomuhangi

Theses and Dissertations--Veterinary Science

Target cell lysis is the hallmark of immune effector responses of cytotoxic T lymphocytes (CTL), natural killer (NK) cells, and monocytes. The most commonly used assay to measure target cell lysis is the 51Cr release assay and is considered the ‘gold standard’. However, this assay has many disadvantages that limit its use by most laboratories. Thus, several alternative assays have been developed. Some of these alternative assays are more sensitive, easy to perform and do not use radioactive elements.

In this study, four of these assays were evaluated for their ability to detect antigen- specific CTL responses in equine blood. …

Anthelmintic Resistance In Equine Parasites: Mechanisms And Treatment Approaches, Jessica Scare Kenealy

Theses and Dissertations--Veterinary Science

Anthelmintic resistance of parasites infecting livestock animals is a global problem resulting in decreased animal welfare and production losses. Horses are not exempt from this issue as wide-spread anthelmintic resistance exists among the equine cyathostomins and Parascaris spp. Of the three drug classes available for treating equine intestinal helminths anthelmintic resistance, defined as less than 90-95% drug efficacy, exist to all three. New pharmaceutical control regimens and the elucidation of parasite drug response mechanisms are needed.

Two studies were carried out evaluating combination deworming regimens. A population of cyathostomins with known resistance to the benzimidazole (BZ) and pyrimidine drug classes …

Mechanisms Of Type-I Ifn Inhibition: Equine Herpesvirus-1 Escape From The Antiviral Effect Of Type-1 Interferon Response In Host Cell, Fatai S. Oladunni

Theses and Dissertations--Veterinary Science

Equine herpesvirus-1 (EHV-1) is one of the most important and prevalent viral pathogens of horses causing a major threat to the equine industry throughout most of the world. EHV-1 primarily causes respiratory disease but viral spread to distant organs enables the development of more severe sequelae; abortion and neurologic disease. In order to produce disease, EHV-1 has to overcome the innate barrier of the type-I interferon (IFN) system in host cells. However, the underlying mechanisms employed by EHV-1 to circumvent the type-I IFN response in host cells are not well understood. In this project study, using molecular techniques, we explored …

Effects Of A Systemic High Urea Concentration On The Endometrial And Embryonic Transcriptomes Of The Mare, Yatta Linhares Boakari

Theses and Dissertations--Veterinary Science

Pregnancy loss remains a major source of economic cost to the equine industry. Frequently, the exact causes of pregnancy loss remain unknown. It has been shown, in other species, that increased dietary protein leading to elevated blood urea nitrogen concentrations (BUN) can be a factor in decreased survival of the early embryo. Our studies provided novel information regarding the effects of elevated BUN on endometrium and embryos from mares as well as insights on changes in their gene expression. Our first objective was to develop an experimental model to elevate BUN during diestrus using intravenous urea infusion. We analyzed the …

Modulation Of Inflammatory Cytokine, Chemokine, And Toll-Like Receptor Genes And Transcriptome Analysis Of Equine Endothelial Cells Following Infection With Equid Herpesvirus-1, And Equine Arteritis Virus., Saranajith Wangisa Dunuwille

Theses and Dissertations--Veterinary Science

EHV-1 is a double-stranded DNA virus whereas EAV is a positive sense, single-stranded RNA virus. Therefore, genetically, they are very different from one another. However, both these viruses are endotheliotropic and thus, infect and replicates in equine endothelial cells resulting in vasculitis. Vasculitis is central to the pathogenesis of these two viruses. Thus, the main objective of this thesis was to investigate the inflammatory and innate immune responses of EECs that contribute towards the development of vasculitis following infection with EHV-1 and EAV in-vitro. Since proinflammatory cytokines and chemokines produced by endothelial cells play a significant role in the …

Characterization And Evaluation Of Androgen-Binding Protein, Sex Hormone-Binding Globulin, And Thyroxine-Binding Globulin In The Horse, Blaire O'Neil Fleming

Theses and Dissertations--Veterinary Science

The objectives of this study are to characterize two carrier proteins in the horse that significantly decrease in humans following anabolic androgenic steroid administration: sex hormone-binding globulin (SHBG) and thyroxine-binding globulin (TBG). For SHBG characterization, qPCR, RNA sequencing, and immunohistochemistry were performed on testes and equine livers. Free and total testosterone immunoassays were utilized to confirm the presence of a carrier protein in equine circulation. SHBG was detected in the testes using qPCR, RNA sequencing, and IHC, indicating the presence of the isoform androgen-binding protein (ABP). SHBG was not detected in any liver samples. Evidence of a carrier protein was …

Effects Of Endophyte-Infected Tall Fescue Seed And Bromocriptine On Endocrine And Immune Function In Horses, Jessica Marie Hanneman

Theses and Dissertations--Veterinary Science

Consumption of endophyte-infected (E+) grasses has long been associated with health problems in animals. In cattle E+ tall fescue consumption leads to fescue toxicosis, and in horses it leads reproductive problems. The health-related issues associated with endophyte consumption have been attributed to the effects caused by the ergot alkaloids produced by the fungus. These ergot alkaloids are considered D2-like receptor agonists, and 5-HT2 serotonin and α-adrenergic receptor partial agonists. Many studies in humans, swine, cattle, and horses have identified that ergopeptines cause a decrease in prolactin production due to their dopaminergic activities. Additionally, these molecules have been found to cause …

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, Victoria A. Taylor

Theses and Dissertations--Veterinary Science

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, …

Biology And Detection Of Pregnanes During Late Gestation In The Mare, Michelle Arelia Ann Wynn

Theses and Dissertations--Veterinary Science

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 …

Lymphocyte-Mediated Inflamm-Aging In The Horse, Melissa Hope Siard

Theses and Dissertations--Veterinary Science

Senior horses (≥20 years) exhibit inflamm-aging, or chronic, low-grade inflammation that occurs systemically with aging, similarly to humans. Inflamm-aging has previously been characterized in the horse in circulation as well as specifically being mediated by lymphocytes and monocytes. In humans, inflamm-aging has been associated with increased morbidity and mortality. However, in the horse, relatively little about inflamm-aging is known regarding clinical effects or factors influencing severity. The contribution of lymphocytes to inflamm-aging of senior horses was examined, specifically through determining the relationships of inflamm-aging with various other health parameters, effects of seasonality, and the extent to which inflamm-aging can be …

Evolution Of Equine Arteritis Virus During Persistent Infection In The Reproductive Tract Of The Stallion And The Male Donkey, Bora Nam

Theses and Dissertations--Veterinary Science

Equine arteritis virus (EAV) establishes persistent infection in the stallion reproductive tract, and the carrier stallion continues to shed virus in semen for weeks to years or lifelong. The objective of this study was to elucidate the intra-host evolution of EAV during persistent infection in stallions. Seven EAV seronegative stallions were experimentally infected with EAV KY84 strain and followed for 726 days post-infection, and sequential clinical samples including semen were collected for virus isolation and next-generation sequencing (NGS). In addition, archived sequential semen samples from two stallions that were naturally infected with EAV KY84 for a long-period (up to 10 …

Role Of Skeletal Paracrine Signals In The Proliferation And Chondrogenic Differentiation Of Interzone Cells, Parvathy Thampi

Theses and Dissertations--Veterinary Science

Articular cartilage in mammals has a limited intrinsic capacity to repair structural injuries and defects, a fact that contributes to the chronic and progressive nature of osteoarthritis. Current treatment modalities do not enable articular cartilage to achieve a complete and permanent restoration of normal structure and function with large or partial thickness lesions. In contrast to mammals, Mexican axolotl salamanders (Ambystoma mexicanum) have demonstrated the remarkable ability to spontaneously and completely repair even large joint cartilage lesions, an intrinsic healing process that involves interzone cells in the intraarticular space. Further, when interzone tissue is transplanted into critical sized …

Effects Of Feeding A Yeast-Based Supplement Containing Docosahexaenoic Acid (Dha) From A Heterotrophically Grown Microalgae, Vitamin E, And Selenium On Stallion Sperm Motion Characteristics, Lauren D. Goedde

Theses and Dissertations--Veterinary Science

The use of cooled and frozen stallion semen has become quite popular. However, there are some stallions that have sperm that are quite susceptible to cold shock. Thus, there is a need for techniques that will alter sperm so that they can withstand the stresses of cooling and freezing and thus improve pregnancy rates achieved with cooled or frozen spermatozoa. Studies have shown that a diet high in omega-3 (n-3) fatty acids can improve the motility of cooled and frozen/thawed sperm. Many of the omega-3 fatty acid products for stallions have low levels of docosahexaenoic acid (DHA) and are based …

Use Of Genomic Tools To Discover The Cause Of Champagne Dilution Coat Color In Horses And To Map The Genetic Cause Of Extreme Lordosis In American Saddlebred Horses, Deborah G. Cook

Theses and Dissertations--Veterinary Science

Champagne dilution of coat color in horses is caused by dominant gene action. Three sire families were identified as segregating for this trait. Genome wide linkage analysis using 104 microsatellite DNA markers was used to map the gene to ECA14 (LOD > 11.0). Four genes, namely SPARC, SLC36A1, SLC36A2 and SLC36A3, were selected from the region implicated by linkage and their exons sequenced. DNA sequences were compared for two homozygotes for Champagne dilution, two heterozygotes and two horses without dilution. A single base change in exon 2 of SLC36A1 was found unique to horses exhibiting Champagne dilution. This change in base …

Examination Of The Snsag Surface Antigen Gene Family In Sarcocystis Neurona, Ablesh Gautam

Theses and Dissertations--Veterinary Science

Sarcocystis neurona is a protozoan parasite that causes the serious neurologic disease equine protozoal myeloencephalitis (EPM). The life cycle of S. neurona progresses through multiple developmental stages that differ morphologically and molecularly. The S. neurona merozoite surface is covered by multiple related proteins, which are orthologous to the surface antigen (SAG) gene family of Toxoplasma gondii. The SAG surface antigens in T. gondii and another related parasite Neospora caninum are life cycle stage-specific and seem necessary for parasite transmission and persistence of infection. The present research was conducted to explore the gene family of SnSAGs in S. …

Role Of Viral And Host Factors In Influenza Virus Mediated Inhibition Of Interleukin-23, Ashish Tiwari

Theses and Dissertations--Veterinary Science

Influenza virus is one of the major respiratory pathogens of humans as well as animals, including equines. There is an increasing evidence that bacterial infections are the most common cause of the death during influenza. In horses also, secondary bacterial pneumonia can lead to death, and surviving horses may take up to six months for the complete recovery resulting in heavy economic loss to the equine industry. Interleukin (IL)-23 mediated innate immune response has been shown to protect the host from various respiratory bacterial infections. However, studies to investigate the role of host and viral factors in the regulation of …

Equine Serum Antibody Responses To Streptococcus Equi And Streptococcus Zooepidemicus, Rafaela De Negri

Theses and Dissertations--Veterinary Science

Streptococcus zooepidemicus (Sz) and Streptococcus equi (Se) share 98% DNA sequence homology, but display different pathogenic properties. Infection by one organism does not cross-protect against the other. To better understand pathogenic differences between these organisms and gain information about which proteins are expressed in horses infected experimentally with Se, intrauterine Sz or naturally with respiratory Sz we compared antibody specificities of convalescent sera using ELISA. These comparisons were based on sets of 8 and 14 immunoreactive recombinant proteins of Se strain CF32 and Sz strain NC78, respectively. Sera from donkeys that were previously naturally affected with strangles and later developed …

Development Of A New Allelic Discrimination Real-Time Pcr Assay For The Diagnosis Of Equine Herpesvirus-1 And Characterization Of The Virulence Determinants Of The Virus, Kathryn L. Smith

Theses and Dissertations--Veterinary Science

Equine herpesvirus-1 (EHV-1) can cause acute upper respiratory tract disease, abortion, neonatal death and neurological disease in horses. Rapid, accurate and timely diagnosis of EHV-1 infection in horses is important to curtail the spread of this pathogen. It has been reported that the neuropathogenic phenotype of EHV-1 can result from a single non-synonymous nucleotide substitution at position 2254 (A→G₂₂₅₄) in open reading frame 30 (ORF30). This was the basis for the development of an allelic discrimination, real-time PCR assay to distinguish between potential neuropathogenic and non-neuropathogenic EHV-1 strains. However, PCR analysis of a panel of EHV-1 abortion isolates …

Evidence For The Maturation Of Cellular Immune Responses In Equine Infectious Anemia Virus-Infected Ponies, Chong Liu

Theses and Dissertations--Veterinary Science

Equine infectious anemia virus (EIAV) has been used as a model to investigate protective mechanisms against lentiviruses. Unlike other lentiviruses, EIAV replication can be eventually controlled in most infected horses leading to an inapparent carrier state free of overt clinical signs which can last for many years. Maintenance of this carrier state is absolutely dependent on active immune responses as evidenced by the fact that immunosuppressive drugs can induce the recurrence of disease. However, the immune mechanisms that are responsible for this control of infection are not yet identified. As the resolution of the initial infection is correlated with the …

Rhodococcus Equi Infection And Interferon-Gamma Regulation In Foals, Lingshuang Sun

Theses and Dissertations--Veterinary Science

Rhodococcus equi (R. equi) is one of the most serious causes of pneumonia in young foals. The clinical disease is of great concern to breeding farms worldwide due to the impact of mortality on economic losses. While adult horses are resistant to R. equi, foals exhibit a distinct age-associated susceptibility. The mechanism underlying this susceptibility in foals is not well understood. Interferon-gamma (IFNg) plays an important role in the clearance of R. equi, but its expression is impaired in neonatal foals. Moreover, the regulation of this age-related IFNg expression in foals remains unknown. In humans, IFNg …