Topic:Pathophysiology
Pathophysiology in horses involves the study of functional changes that occur in the body as a result of disease or injury. This field examines the mechanisms through which diseases develop and progress, as well as how they affect the body's normal physiological processes. In equine research, pathophysiology encompasses a wide range of conditions, including respiratory disorders, musculoskeletal injuries, gastrointestinal diseases, and metabolic syndromes. Understanding these processes helps in identifying potential therapeutic targets and developing effective treatment strategies. This page collects peer-reviewed research studies and scholarly articles that explore the underlying mechanisms, clinical manifestations, and implications of various pathophysiological conditions in equine health.
Investigation of hydration processes of the equine hoof via nuclear magnetic resonance microscopy. To examine the distribution of water in hoof wall specimens of horses via nuclear magnetic resonance (NMR) microscopy and determine changes in water distribution during hydration. Methods: 4 hoof wall specimens (2 obtained from the dorsum and 1 each obtained from the lateral quarter and lateral heel regions) of the stratum medium of healthy hooves of 1 horse. Methods: Equine hoof wall specimens were examined via NMR microscopy. Proton density-weighted 3-D images were acquired. Changes during water absorption were assessed on sequential images. Results: The inner zone of the stratum medium had ...
Synovial fluid D-dimer concentration in horses with osteochondritis dissecans and osteoarthritis. To assess the synovial fibrinolytic pathway activation in adult horses with developmental and degenerative arthropathies such as osteochondritis dissecans (OCD) and osteoarthritis (OA) by measuring synovial D-dimer concentrations. Methods: Prospective observational clinical study of horses admitted for OCD or OA. Synovial fluid was collected during lameness examination or prior to the surgical procedure, and D-dimer concentration and routine synovial fluid analysis were performed. Results: Fifty-eight horses (14 with OCD, 10 with OA and 34 controls) were included in this study. Synovial D-dime...
Farriery for the hoof with low or underrun heels. Underrun heels are common and involve hoof capsule distortion in which the horn tubules of the heels undergo bending and lengthening, resulting in decreased strength and functionality. The syndrome varies in clinical presentation, depending on duration, severity of distortion, presence of secondary problems, and presence of lameness. Primary treatment goals are to maintain soundness and functional integrity of the foot and to establish a normal hoof capsule. Resolution of the problem is generally not achieved in horses in a heavy work schedule, and realistic goals in this situation are to main...
Treating laminitis: beyond the mechanics of trimming and shoeing. Laminitis is typically classified into developmental or prodromal, acute, subacute, and chronic phases. Scientific evidence regarding the pathophysiology of laminitis does exist, but it is often conflicting and dependent on the clinician's interpretation/understanding of the study or the model used for inducing laminitis. The diagnosis of laminitis consists of obtaining an accurate history, performing a thorough physical examination, and taking good-quality radiographs. The use of radiographs for diagnosis and interpretation of laminitis is an absolute necessity for the clinician. Laminitis is...
Non-genomic action of beclomethasone dipropionate on bronchoconstriction caused by leukotriene C4 in precision cut lung slices in the horse. Glucocorticoids have been proven to be effective in the therapy of recurrent airway obstruction (RAO) in horses via systemic as well as local (inhalative) administration. Elective analysis of the effects of this drug on bronchoconstriction in viable lung tissue offers an insight into the mechanism of action of the inflammatory cascade occurring during RAO which is still unclear. The mechanism of action of steroids in treatment of RAO is thought to be induced through classical genomic pathways. We aimed at electively studying the effects of the glucocorticoid beclomethasone dipropionate on equi...
Effects of a “two-hit” model of organ damage on the systemic inflammatory response and development of laminitis in horses. The role of endotoxemia in the development of laminitis remains unclear. Although systemic inflammation is a risk factor for laminitis in hospitalized horses, experimental endotoxin administration fails to induce the disease. While not sufficient to cause laminitis by itself, endotoxemia might predispose laminar tissue to damage from other mediators during systemic inflammation. In "two-hit" models of organ damage, sequential exposure to inflammatory stimuli primes the immune system and causes exaggerated inflammatory responses during sepsis. Acute laminitis shares many characteristics with se...
Mechanisms of oxidative injury in equine disease. Oxygen is essential to aerobic life, but it is also associated with the production of highly reactive compounds that can pose danger to physiologic systems when the oxygen concentration is excessive. Reactive oxygen species (ROS) are required for normal physiologic processes, but when produced in excess, they can overwhelm endogenous antioxidants, resulting in significant cellular damage and, eventually, cell death. Ischemic events can initiate numerous pathophysiologic mechanisms leading to increased production of ROS, loss of cellular energy production, and lipid peroxidation. Although reper...
Intestinal ischemia-reperfusion injury in horses: pathogenesis and therapeutics. This article discusses the potential role of oxidative injury to the intestinal tract of horses and the therapeutic approaches that have been investigated to decrease cellular damage secondary to ischemia-reperfusion (IR) injury. Equine colic is a major concern for horse owners and veterinary practitioners. Strangulating and obstructive lesions of the small and large intestines commonly require intervention in patients via exploratory celiotomy. However, the application of information from experimentally induced IR injury in horses to clinical cases of naturally occurring equine colic is not c...
Effects of the addition of endotoxin during perfusion of isolated forelimbs of equine cadavers. To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. Methods: Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). Methods: Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of ...
Histological and morphometric lesions in the pre-clinical, developmental phase of insulin-induced laminitis in Standardbred horses. Lamellar pathology in experimentally-induced equine laminitis associated with euglycaemic hyperinsulinaemia is substantial by the acute, clinical phase (∼48h post-induction). However, lamellar pathology of the developmental, pre-clinical phase requires evaluation. The aim of this study was to analyse lamellar lesions both qualitatively and quantitatively, 6, 12 and 24h after the commencement of hyperinsulinaemia. Histological and histomorphometrical analyses of lamellar pathology at each time-point included assessment of lamellar length and width, epidermal cell proliferation and death, base...
Evaluation of high-molecular weight adiponectin in horses. To characterize adiponectin protein complexes in lean and obese horses. Methods: 26 lean horses and 18 obese horses. Procedures-Body condition score (BCS) and serum insulin activity were measured for each horse. Denaturing and native western blot analyses were used to evaluate adiponectin complexes in serum. A human ELISA kit was validated and used to quantify high-molecular weight (HMW) complexes. Correlations between variables were made, and HMW values were compared between groups. Results: Adiponectin was present as a multimer consisting of HMW (> 720-kDa), low-molecular weight (180-kDa)...
The emerging pathophysiology of age-related testicular degeneration with a focus on the stallion and an update on potential therapies. Studies in laboratory rodents are shedding light on the pathophysiology of testicular ageing and now suggest a complicated basis for age-related declines in testicular function. A highly significant contributor to infertility may involve failure of specific and complex testicular microenvironments (niches) comprised of a variety of cellular and molecular components. Our laboratory has applied testis tissue xenografting to the study of testicular ageing in the stallion. Using this technique, we have confirmed that the disease is tissue autologous. As would be expected from a tissue autologous d...
Hyperlipidaemia in trypanosomiasis of naturally infected horses: possible cachexia-anorexia syndrome? Trypanosomiasis caused by Trypanosoma evansi commonly produces wasting disease with signs of emaciation and cachexia mainly at the end stage. The present study was conducted to explore the possible hyperlipaemia or hyperlipidaemia and its association with cachexia-anorexia in equine trypanosomiasis. Out of the fifteen confirmed animals, none of the plasma sample was opaque. There was a significant increase in plasma triglyceride, total cholesterol and blood urea nitrogen and a highly significant increase in low-density lipoprotein (LDL) levels. A mild increase in high-density lipoprotein (HDL)...
Novel link between inflammation and impaired glucose transport during equine insulin resistance. Although insulin resistance (IR) has been increasingly recognized in horses, a clear understanding of its pathophysiology is lacking. The purpose of the present study was to determine the early pathologic changes in IR horses by characterizing alterations in proteins that play key roles in innate immunological responses and inflammatory pathways, and by identifying potential links with glucose transport and insulin signaling. Visceral (VIS) and subcutaneous (SC) adipose tissue and skeletal muscle (SM) biopsies were collected from horses, which were classified as insulin-sensitive (IS) or IR ba...
Contractile responses of isolated equine digital arteries under hypoxic or hyperoxic conditions in vitro: role of reactive oxygen species and Rho kinase. The underlying pathophysiological triggers for equine acute laminitis are unknown, although digital vasoconstriction, ischaemia, hypoxia and reperfusion injury may be involved. The contractile responses of isolated equine digital arteries (EDAs), harvested from the hindlimbs of normal horses postmortem at an abattoir, were studied acutely (up to 3 h) under hyperoxic (95% oxygen, 5% CO2 ) and hypoxic (95% nitrogen, 5% CO2 ) conditions in organ baths. Phenylephrine (PHE; 10(-6) m), 5-hydroxytryptamine (5-HT; 10(-7) m) and high potassium (K(+) ; 118 mm) caused contraction in EDAs which was signif...
Corticosteroids and antigen avoidance decrease airway smooth muscle mass in an equine asthma model. Recent studies suggest that airway smooth muscle remodeling is an early event in the course of asthma. Little is known of the effects of long-term antigen avoidance and inhaled corticosteroids on chronically established airway remodeling. We sought to measure the effects of inhaled corticosteroids and antigen avoidance on airway remodeling in the peripheral airways of horses with heaves, a naturally occurring asthma-like disease. Heaves-affected adult horses with ongoing airway inflammation and bronchoconstriction were treated with fluticasone propionate (with and without concurrent antigen av...
DNA hypomethylation and oxidative stress-mediated increase in genomic instability in equine sarcoid-derived fibroblasts. It is widely accepted that equine sarcoid disease, the most common skin associated neoplasm in equids, is induced by bovine papillomavirus (BPV-1). Although BPV-1 DNA has been found in almost all examined sarcoids so far, its detailed impact on the horse's host cell metabolism is largely unknown. We used equine fibroblast cell lines originating from sarcoid biopsies to study BPV-1-associated changes on DNA methylation status and oxidative stress parameters. Sarcoid-derived fibroblasts manifested increased proliferation in vitro, transcriptional rDNA activity (NORs expression) and DNA hypometh...
A method for proteomic analysis of equine subchondral bone and epiphyseal cartilage. Proteomic analyses of cartilage and, to a lesser extent, of bone have long been impaired because of technical challenges related to their structure and biochemical properties. We have developed a unified method based on phenol extraction, 2DE, silver staining, and subsequent LC-MS/MS. This method proved to be efficient to characterize the proteome of equine cartilage and bone samples collected in vivo. Since proteins from several cellular compartments could be recovered, our procedure is mainly suitable for in situ molecular physiology studies focused on the cellular content of chondrocytes, o...
Factors influencing placental development and function in the mare. The development of the equine placenta involves a series of stage-specific events which ensure that the fetus is nourished throughout its 11 months of gestation. Initially, placental exchange to the developing embryo is histotrophic, via the yolk sac but, as the allantochorion develops and microcotyledons form, haemotrophic nutrition plays the major role in sustaining the increasing demands of the growing fetus. This review describes the development of the allantochorionic placenta of the mare and discusses some of the factors that influence its growth, size and functions and, hence, its contr...
Diabetes, insulin resistance, and metabolic syndrome in horses. Analogous to the situation in human medicine, contemporary practices in horse management, which incorporate lengthy periods of physical inactivity coupled with provision of nutritional rations characterized by inappropriately high sugar and starch, have led to obesity being more commonly recognized by practitioners of equine veterinary practice. In many of these cases, obesity is associated with insulin resistance (IR) and glucose intolerance. An equine metabolic syndrome (MS) has been described that is similar to the human MS in that both IR and aspects of obesity represent cornerstones of it...
Finite element analysis in 3-D models of equine cheek teeth. Periodontal diseases occur frequently in equine dentistry and excessive strain in biological tissues is assumed to be a predisposing factor in their development. Finite element (FE) analysis enables strains and stresses occurring in the periodontium to be calculated and is a useful tool for testing this hypothesis. The current study aimed to establish reliable 3-D models from equine maxillary and mandibular cheek teeth for use in FE simulations, with particular attention to the detailed construction of the periodontal ligament (PDL). Age-related morphological aspects of the teeth and the perio...
Evidence of oxidative injury of the spinal cord in 2 horses with equine degenerative myeloencephalopathy. The cervical spinal cords of 2 horses with equine degenerative myeloencephalopathy (EDM) were evaluated for evidence of oxidative damage to the central nervous system (CNS) using immunohistochemical staining for 3-nitrotyrosine (3-NT) and 4-hydroxynonenol (4-HNE). Neurons of the CNS from horses with EDM had positive immunohistochemical staining, whereas control samples did not, thus supporting the theory that oxidative damage is a potential underlying factor in horses with EDM. In addition, serum vitamin E concentration was low in both EDM-affected horses, and vitamin E concentration was also ...
Effects of ischemia and reperfusion on production of nitrotyrosine, activation of eosinophils, and apoptosis in the large colonic mucosa of horses. To assess the effects of ischemia and reperfusion on indicators of oxidative stress, activation of eosinophils, and apoptosis in the large colonic mucosa of horses. Methods: 40 horses. Methods: In 1 or two 20-cm-long segments of the pelvic flexure, ischemia was induced for 1 or 2 hours followed by no reperfusion or 30 minutes and 18 hours of reperfusion in anesthetized horses. Mucosal specimens were collected before (controls; n = 20 horses) and after each period of ischemia, and full-thickness tissue samples were collected after each period of reperfusion. Sections of colonic tissues were sta...
Comparison of cytokine mRNA expression in the bronchoalveolar lavage fluid of horses with inflammatory airway disease and bronchoalveolar lavage mastocytosis or neutrophilia using REST software analysis. The pathophysiology of inflammatory airway disease (IAD) is unknown, but in some cases involves the accumulation of mast cells, neutrophils, or both in the bronchoalveolar lavage fluid (BALF). The objective of this study was to characterize cytokine gene expression in the BALF cells of horses with IAD, including a comparison of cytokine gene expression between IAD horses with increased BALF mast cells (IAD-Mast) or neutrophils (IAD-Neutro). Methods: The mRNA expression of IL-4, IFN-γ, IL-17, IL-8, IL-1β, IL-5, IL-6, IL-10, IL-12p35, and eotaxin-2 was studied by quantitative polymerase chain ...
Production of free radicals and oxygen consumption by primary equine endothelial cells during anoxia-reoxygenation. The endothelium plays an active role in ischemia/reperfusion injuries. Herein, we report the effect of a single or successive cycles of anoxia/reoxygenation (A/R) on the mitochondrial respiratory function of equine endothelial cells (cultured from carotids) monitored by high resolution oxymetry, and on their production of reactive oxygen species (ROS). ROS were measured by electron paramagnetic resonance (ESR) using POBN and DMPO spin traps, and by gas chromatography (GC) of ethylene released by ROS-induced α-keto-γ-(methylthio)butyric acid (KMB) oxidation. The oxygen consumption significant...