Medicine and Health Sciences Commons^™

Equine Fecal Microbiota Response To Short Term Antibiotic Administration, Jordan Lacey Parker

Theses and Dissertations--Veterinary Science

Though generally regarded as safe, research continues to demonstrate negative side effects of antibiotic administration on the gastrointestinal (GIT) microbiota across species. In horses, antibiotic associated diarrhea (AAD) is a life-threatening side effect linked to the GIT microbiota. This study tested the hypothesis that short term antibiotic administration to healthy horses would negatively impact the fecal microbiota as measured by their ability to digest nutrients and produce short chain fatty acids (SCFAs). Twenty-four horses were assigned to one of four treatments: control (CO); potassium penicillin/gentamicin sulfate (KPG); ceftiofur crystalline free acid (EX); trimethoprim/sulfamethoxazole (SMZ); and treated for 4 days. Fecal …

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 …

Identifying Bisphosphonate Protein Biomarkers In Equine Sera Using Mass Spectrometry Methods, Malinda Jayne Alison Porter

Theses and Dissertations--Veterinary Science

Bone resorptive diseases affect humans and horses, alike. Examples of these diseases include osteoporosis, Paget’s disease, and osteogenesis imperfecta in humans, and navicular disease in the horse (Mitchell et al., 2019; Suva et al., 2021). Bisphosphonates are used to treat these diseases, and may remain in the bone for several years after administration, demonstrating the need for newer drug testing methods.

The purpose of the discovery phase of this study was to use blood samples of in-training horses which had been given an initial administration of the bisphosphonate tiludronate and identify protein biomarkers that changed in response to this class …

The Effects Of Cannabidiol On Senior Equine Health, Shelley Turner

Theses and Dissertations--Veterinary Science

Cannabis sativa L., has been revealed to produce hundreds of phytocannabinoids, of which cannabidiol (CBD) is one of the most desired. It has been revealed that CBD can potentially treat inflammation and act as an analgesic in humans without psychoactive effects of delta-9-tetrahydrocannabinol (THC). Recently, there has been interest in understanding the potential health benefits of CBD for horses. With an increasing senior horse population (< 15 years old), alternatives to the use of non-steroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone, firocoxib, and flunixin meglumine, are desired as these common anti-inflammatory treatments have negative side effects. Because senior horses may have chronic low-grade inflammation, termed inflamm-aging, they are a natural model to investigate the efficacy of CBD on inflammatory responses as well as other health parameters. Given this interest, and due to the lack of research conducted on CBD in the horse, the overall objective of this dissertation work was to conduct both basic and applied research investigating the effects of CBD on equine immune function and health. The first objective was to determine the in vitro effects of CBD as an anti-inflammatory. Peripheral blood mononuclear cells (PBMCs) from senior horses were cultured in vitro with increasing concentrations of pure CBD dissolved in dimethyl sulfoxide (DMSO). These cells were …

The Effect Of Intra-Articular Corticosteroids On The Systemic Messenger Rna Response In An Equine Experimental Inflammation Model, Emma Elaine Partridge

Theses and Dissertations--Veterinary Science

Intra-articular (IA) corticosteroids are regularly used in equine athletes for the control of joint inflammation. The goal of this study was to utilize an acute synovitis inflammation model to determine the residual effects of IA betamethasone and triamcinolone acetonide on various inflammatory parameters and lameness.

Five mixed-breed, 2-year-old horses were randomly allocated to an IA treatment of the radiocarpal joint with 9 mg of either betamethasone or triamcinolone acetonide. Two weeks following treatment, horses were injected with 1μg of lipopolysaccharide (LPS) diluted in 1 mL of 0.9% sterile saline. Following LPS injection, horses were crossed-over and both sets of injections …

Maturation Of Equine Proximal Sesamoid Bones In Thoroughbred Horses, Angela Maria Mangine

Theses and Dissertations--Veterinary Science

Proximal sesamoid bone (PSB) injuries account for approximately 50% of all fatal catastrophic musculoskeletal injuries in Thoroughbred racehorses. In addition, PSB fractures are not uncommon in Thoroughbred foals and yearlings as a result of energetic or intense free exercise. The ability to interpret some PSB pathology assessments, however, is more difficult given the limited information published on the normal development and maturation of these paired sesamoid bones. In addition, the level of normal variation in PSB morphological and structural parameters within the Thoroughbred population as a function of age, body size, gender, and inter-animal variation are not well documented, complicating …

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 …

Structural Adaptation Of Equine Proximal Sesamoid Bones To High-Speed Exercise, Kathryn Mary Babiarz

Theses and Dissertations--Veterinary Science

Proximal sesamoid bone (PSB) fractures are one of the most commonly reported catastrophic musculoskeletal injuries (CMI) in Thoroughbred racing. Despite the seriousness of these injuries, an understanding of the structural changes that occur normally within PSBs in response to the biomechanical forces of high-speed exercise and how they relate to pathological events leading to fracture remain limited. To address this critical knowledge gap, PSBs from Thoroughbred horses were analyzed with both computed tomography (CT) and microcomputed tomography (µCT) to assess their morphological and structural parameters. Comparisons were made using samples from the left and right forelimbs of Thoroughbreds of both …

An Assessment Of The Carrier State And A Novel Marker Of Leptospira And Abortion In Central Kentucky Horses, Gloria Louise Gellin

Theses and Dissertations--Veterinary Science

Leptospirosis is a reemerging zoonotic infection of worldwide importance and affects all mammals. The bacterium is transmitted to animals and humans by urine, fetal membranes and body fluids. Leptospira shedding in the urine contaminates both soil and water, exposing both humans and animals to the bacterium. Leptospirosis in horses can cause abortion and is one of the etiologies of equine recurrent uveitis which can lead to blindness. Equine leptospiral abortion in Central Kentucky is primarily caused by serovar Pomona, with occasional cases attributed to serovar Grippotyphosa. There are a few reports in the literature attributing abortion to serovar Bratislava in …

Host-Parasite Interaction In Horses: Mucosal Responses To Naturally Acquired Cyathostomin Infections And Anthelmintic Treatment, Ashley Elaine Steuer

Theses and Dissertations--Veterinary Science

Cyathostomins are ubiquitous parasites in equids. In rare cases, cyathostomins lead to a generalized typhlocolitis and death. In healthy horses, local reactions are noted to the mucosal larvae; however, the mechanisms and importance of these reactions have not been elucidated. It has been hypothesized that anthelmintics can alter these reactions. Currently, three drug classes are approved for use in horses against cyathostomins; while all products target the adults, only two products are labeled as larvicidal. Adulticidal therapy is implicated in triggering the typhlocolitis, however, current evidence is contradictory. There is also conjecture that the larvicidal drugs can increase the risk …

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 …

Effects Of Pituitary Pars Intermedia Dysfunction And Prascend® Treatment On Endocrine And Immune Function In Senior Horses, Ashton B. Miller

Theses and Dissertations--Veterinary Science

Pituitary pars intermedia dysfunction (PPID) is one of the most common endocrine diseases affecting senior horses. PPID causes abnormally high concentrations of adrenocorticotropic hormone (ACTH) in the plasma and a very distinct, long, shaggy haircoat (hypertrichosis). At present, the recommended treatment for PPID is daily oral administration of pergolide mesylate. Due to the increased ACTH levels associated with PPID, it is commonly thought that these horses are immunosuppressed and at increased risk of opportunistic infections, although current research in this area is sparse. Additionally, it is not well-understood how treatment with Prascend^® (pergolide tablets) affects endocrine measures other than …

Cellular And Molecular Basis Of Equine Arteritis Virus Persistent Infection In The Stallion Reproductive Tract: Characterization Of Local Host-Pathogen Interactions Mediating Long-Term Viral Persistence, Mariano Carossino

Theses and Dissertations--Veterinary Science

Equine arteritis virus (EAV) has a global impact on the equine industry being the causative agent of equine viral arteritis (EVA), a reproductive, respiratory, and systemic disease of equids. A distinctive feature of EAV infection is that it establishes long-term persistent infection in the reproductive tract of stallions and is continuously shed in the semen (carrier state). Recent studies showed that long-term persistence is associated with a specific allele of the CXCL16 gene (CXCL16S). However, the cellular and molecular mechanisms underlying the establishment and maintenance of persistent infection are yet to be determined. The studies were undertaken herein …

Rhodococcus Equi In The Foal – Improving Diagnostic And Prevention Measures, Fernanda Bicudo Cesar

Theses and Dissertations--Veterinary Science

Although Rhodococcus equi (R. equi), previously known as Corynebacterium equi, was first isolated from pneumonic foals almost a century ago, it remains the most common cause of subacute or chronic granulomatous bronchopneumonia in foals. While the majority of foals exposed to R. equi develop a protective immune response (regressors), others exhibit a unique susceptibility to infection (progressors). The determinants for either outcome are not completely understood. Therefore, current diagnostic and preventive measures are suboptimal and require betterment. In light of this current need, we hypothesized that immunoglobulin G subisotype T [IgG(T)] against the virulence-associated protein A (VapA) …

Analysis Of Humoral Immune Responses In Horses With Equine Protozoal Myeloencephalitis, Catherine-Jane Angwin

Theses and Dissertations--Veterinary Science

Equine protozoal myeloencephalitis (EPM), caused by the protozoan parasite Sarcocystis neurona, is one of the most important neurological diseases of horses in the Americas. While seroprevalence of S. neurona in horses is high, clinical manifestation of EPM occurs in less than 1% of infected horses. Factors governing the occurrence and severity of EPM are largely unknown, although horse immunity might play an important role in clinical outcome. We hypothesize that EPM occurs due to an aberrant immune response, which will be discernable in the equine IgG subisotypes a, b, and (T) that recognize S. neurona in infected diseased horses versus …

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 …

Inflammation And Insulin Dysregulation In The Horse, Sarah E. Elzinga

Theses and Dissertations--Veterinary Science

Insulin dysregulation (ID) in the horse is receiving increasing attention as a serious health concern, in particular due to its association with the potentially career or life ending condition, laminitis. The role of inflammation and the immune system in ID as well as its associated health concerns has also been raised. However, the involvement of inflammation in and mechanisms behind ID in the horse remain unclear. Therefore, our overall hypothesis was that due in part to changes in their gut microbiota and plasma lipidome, horses with ID have changes in circulating proinflammatory markers, in particular in response to glycemic challenge, …

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 …

An Investigation Into Specific Seminal Plasma Proteins And Their Effect On The Innate Immune Response To Breeding In The Mare, Carleigh Elizabeth Fedorka

Theses and Dissertations--Veterinary Science

The mare experiences a transient innate immune response to breeding, the resolution of which is crucial for optimal fertility. The majority of mares are able to modulate this inflammation in a timely fashion, but a subpopulation exists which fail to do so and are considered susceptible to persistent breeding-induced endometritis (PBIE). Seminal plasma has been shown to modulate aspects of this inflammation. Recently, two seminal plasma proteins have garnered interest for their immune modulating properties: cysteine-rich secretory protein-3 (CRISP-3) and lactoferrin. These proteins have been found to alter the binding between sperm and neutrophils based on sperm viability in vitro …

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 …

Differential Gene Expression In Equine Cartilaginous Tissues And Induced Chondrocytes, Emma N. Adam

Theses and Dissertations--Veterinary Science

Degenerative joint disease, or osteoarthritis, is a major cause of lameness and morbidity in horses, humans, and dogs. There are no truly satisfactory cures for this widespread problem and current treatments all have limitations or unwanted side effects.

New cell-based strategies to repair joint surface lesions have generated a high level of interest, but have yet to achieve the full restoration of articular cartilage structure and function. Currently used therapy cells include autologous chondrocytes and adult mesenchymal cells such as bone marrow derived cells and adipose derived cells. Unfortunately, the resultant repair tissue is biomechanically inferior fibrocartilage. A critical gap …

Uterine Artery Rupture, An Angiopathy Of The Reproductive System Of The Mare: Occurrence And Potential Effects, Ana G. Toro Mayorga

Theses and Dissertations--Veterinary Science

The intent of this research was to identify if the degenerative changes within arteries in the endometrium (endometrial angiopathies) correlate with degenerative changes in the uterine arteries and can be used as a predictor of increased risk for uterine artery rupture (UAR). With this objective specimens from 20 mares that died from uterine artery rupture and 21 control mares that died from unrelated causes were obtained from cases submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) over a two-year period. Postmortem specimens of each mare were collected from the left and right uterine arteries at the origin, bifurcation, …

Reversible Downregulation Of Hypothalamic-Pituitary-Gonadal Axis In The Stallion With A Third-Generation Gnrh Antagonist, Gabriel Monteiro Davolli

Theses and Dissertations--Veterinary Science

The objectives of this thesis were: (1) to evaluate the downregulation of the stallion hypothalamic-pituitary-gonadal (HPG) axis by a GnRH antagonist (acyline) based upon endocrine, seminal, testicular and behavioral effects, and (2) to assess recovery after treatment. Stallions were treated for 50 days (n=4; 330µg/kg acyline q 5d) and controls (n=4) received vehicle alone. Stallions were assessed pre-treatment and for 72 days after last treatment. Treatment induced declines (p<0.05) in FSH, LH, testosterone (to castrate levels) and estrone sulfate. Gonadotropins and testosterone returned to control values within nine days and estrone sulfate by 14 days after treatment discontinuation. Acyline-treated stallions failed to respond with FSH, LH and testosterone increase after exogenous GnRH stimulation (25µg gonadorelin, IV) compared to pre-treatment and control stimulation. Total sperm numbers and motility were reduced in acyline-treated stallions, as well as total seminal plasma protein and testicular volume (p<0.05). Time to ejaculation was increased in acyline group (p<0.5). Testicular, sexual behavior and most seminal parameters regained normal levels within 72 days after treatment ceased. Sperm output of acyline-treated stallions was regained within seven months after ending treatment. Acyline reversibly suppressed the stallion HPG axis, thus has potential for treating the androgen-dependent Equine-Arteritis-Virus carrier state and as behavior modulator.

Glucocorticoid-Induced Chondrocyte Cytotoxicity At Doses Recommended For Intra-Articular Therapy In Horses, Wenying Zhu

Theses and Dissertations--Veterinary Science

Intra-articular glucocorticoid injections are commonly used to treat synovitis and osteoarthritis in horses. These agents are highly effective at relieving pain, swelling, and other symptoms of joint inflammation. The drugs also have therapeutic benefits by down regulating the expression of cytokines and protease enzymes that participate in the degradation of articular cartilage. However, detrimental effects on chondrocyte function and cell viability that is independent of osteoarthritis pathogenesis have been described and linked to glucocorticoid use. These side effects are both drug- and dose-dependent. This study tested the hypothesis that manufacture recommended dosage levels of methylprednisolone, betamethasone, and triamcinolone that are …

Studies On Equine Placentitis, Igor Frederico Canisso

Theses and Dissertations--Veterinary Science

Two types of placentitis were studied: ascending and nocardioform placentitis. Although the first diagnosis of nocardioform placentitis was made three decades ago, little is known about the disease, due to the lack of an experimental model. In attempt to develop a research model, Crossiela equi was inoculated through intrauterine, intravenous, intrapharyngeal, and oral routes, but none of the routes resulted in nocardioform placentitis. This may indicate that unidentified factors may play a role in disease pathogenesis and that simple presence of bacteria is not sufficient to induce nocardioform placentitis. The second and major component of this dissertation involved the identification …

Anti-Müllerian Hormone In Stallions And Mares: Physiological Variations, Clinical Applications, And Molecular Aspects, Anthony N.J. Claes

Theses and Dissertations--Veterinary Science

Anti-Müllerian hormone (AMH) is a homodimeric glycoprotein that is best known for its role in regression of the Müllerian duct in the male fetus. Accumulating evidence indicates that AMH also has an important role during different physiological processes after birth. In contrast to other species, relatively little is known about AMH in the horse. In chapter one, developmental and seasonal changes in serum AMH concentrations in male horses were determined, and the use of AMH for determination of retained cryptorchid testes was established. In chapter two, the interrelationship between plasma AMH concentrations, antral follicle counts (AFC), and age in mares …

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. …