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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.
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...
Assessment of endogenous growth hormone pulsatility in gelded yearling horses using deconvolution analysis. Defining normal Growth Hormone (GH) secretory dynamics in the horse is necessary to understand altered GH dynamics related to issues like welfare and disease. Methods: Twelve healthy yearlings and two mature Standardbreds were used to quantify GH secretion. Endogenous GH half-life was determined after administration of 1.0 µg/kg BW GH releasing hormone (GHRH). Exogenous GH half-life was determined after administration of 20 µg/kg BW recombinant equine GH (reGH) with and without suppression of endogenous GH secretion by somatostatin infusion (50 µg/m(2)/h). Pulse detection algorithm (C...
Differentiation of ataxic and orthopedic gait abnormalities in the horse. The differentiation of ataxia and orthopedic disease can be facilitated by the use of several additional tests, not commonly part of either neurologic or orthopedic examination protocols. However, a full neurologic and orthopedic examination and suitable diagnostic imaging will of course also be necessary in such cases. The common association of orthopedic and neurologic disease makes it even more necessary to correctly attribute movement or posture abnormalities to potentially treatable structures.
Neonatal encephalopathy in foals. Neonatal encephalopathy is a common central nervous system disorder of neonatal foals and human infants, resulting in clinical signs such as lethargy, inappropriate behavior, seizures, and other neurologic deficits. Although neonatal encephalopathy is frequently seen in equine practice, a paucity of veterinary clinical and basic science research data is available. Therefore, the pathophysiologic mechanisms of this disorder in equids, such as energy deprivation, excess excitatory amino acids, and free radical injury, have been extrapolated from human medicine. Equine veterinarians have used var...
Pathogen associated molecular pattern motifs from Gram-positive and Gram-negative bacteria induce different inflammatory mediator profiles in equine blood. Although the incidence of Gram-positive infection in horses is increasing, little is known about differences in inflammatory response between Gram-positive and Gram-negative organisms in this species. Equine blood was stimulated with components of both Gram-negative and Gram-positive organisms: lipopolysaccharide (LPS); lipoteichoic acid (LTA); peptidoglycan (PG); with combinations of LPS, LTA and PG; and with phosphate buffered saline (control). LPS, LTA and PG stimulated tumor necrosis factor (TNF) and interleukin (IL)-6 production but only LTA and PG stimulated IL-1β production from whole ...
Pharmacokinetics of gallium nitrate after oral administration in adult horses–pilot study. Gallium (Ga), a metal in group IIIA of the periodic table, has shown a remarkable activity against bone resorption and could therefore possibly prove useful in the treatment of certain diseases in sport horses, for example navicular disease. The aim of this study was to gain more information concerning the kinetics of Ga after oral administration of gallium nitrate (GaN) in adult horses. Six horses received a single dose of 10 mg/kg of GaN mixed with the food ration. Absorption was slow (T(max) = 10 ± 3 h, T(½abs) = 2 ± 0.8 h), and a C(max) of 26 ± 11 μg/L was achieved. Excretion followed...
Digital hypothermia inhibits early lamellar inflammatory signalling in the oligofructose laminitis model. The pathophysiological events inhibited by prophylactic digital hypothermia that result in reduction of the severity of acute laminitis are unknown. Objective: To determine if digital hypothermia inhibits lamellar inflammatory signalling during development of oligofructose (OF) induced laminitis. Methods: Fourteen Standardbred horses were given 10 g/kg bwt OF by nasogastric tube with one forelimb (CRYO) continuously cooled by immersion in ice and water and one forelimb (NON-RX) at ambient temperature. Lamellae were harvested prior to the onset of lameness (24 h post OF administration, DEV ...
Endoscopic assessment of airway inflammation in horses. Comprehensive endoscopic scoring of the upper and lower airways for inflammation has not been critically assessed among a large population of horses. The relationship between upper and lower airways described in humans by the "one airway, one disease" concept might also apply to horses. Objective: To evaluate if an association exists between endoscopic inflammatory scores and mucus scores of upper and lower airways and to investigate if endoscopic findings correlate with the lower airway inflammation measured by bronchoalveolar lavage (BAL) cytology. Methods: Prospective field study. Pharyngit...
Exercise-induced pulmonary hemorrhage in horses: the role of pulmonary veins. While airway endoscopy and bronchoalveolar lavage are the methodsof choice for diagnosing exercise-induced pulmonary hemorrhage (EIPH), these techniques do not allow accurate evaluation of the severity of bleeding. EIPH pathology is characterized by occlusive remodeling of pulmonary veins. Affected veins have large collagen deposits in their walls, which reduces their lumens. In the caudodorsal regions, pulmonary vein wall remodeling is associated with hemosiderin accumulation, bronchial circulation angiogenesis, and fibrosis of the alveolar interstitium, bronchovascular bundle, septa, and ple...
Equine recurrent uveitis: classification, etiology, and pathogenesis. Equine recurrent uveitis is a cyclical disease that affects the eye and often leads to high management costs and unfavorable results, such as blindness. Research has improved understanding of the roles of various etiologies, especially leptospirosis, in initiating and perpetuating the pathogenesis of equine recurrent uveitis. Research has also led to the discovery that specific breeds and horses with specific coat color patterns may be predisposed to developing recurrent uveitis.
A systematic review of the efficacy of interventions for dynamic intermittent dorsal displacement of the soft palate. There are numerous treatments for correction of dorsal displacement of the soft palate (DDSP). However, the efficacy of these treatments is controversial and there is little consensus on how best to treat this condition. The aims of this study were to systematically review the literature and to assess the evidence on the clinical effects of interventions for dynamic intermittent DDSP. A secondary objective was to assess whether factors relating to study quality affected reported success rates. Twenty-three studies were included, covering a wide number of interventions but also differing widely...
Possible role of carpal hyperextension in superficial digital flexor tendinopathy. The specific biomechanical circumstances that induce excessive superficial digital flexor tendon (SDFT) strain in horses are unknown. Objective: Carpal joint hyperextension during axial limb loading during the middle of stance disproportionately enhances SDFT strains compared to suspensory ligament (SL) strains. Methods: Superficial digital flexor tendon and SL strains were measured in 7 cadaver limbs during in vitro loading that maintained carpal extension or allowed carpal hyperextension by constraining, or allowing rotation of, the radius during loading conditions that simulated the middle ...
Heaves, an asthma-like disease of horses. Animal models have been developed to investigate specific components of asthmatic airway inflammation, hyper-responsiveness or remodelling. However, all of these aspects are rarely observed in the same animal. Heaves is a naturally occurring disease of horses that combines these features. It is characterized by stable dust-induced inflammation, bronchospasm and remodelling. The evaluation of horses during well-controlled natural antigen exposure and avoidance in experimental settings allows the study of disease mechanisms in the asymptomatic and symptomatic stages, an approach rarely feasible ...
The effect of nonsteroidal anti-inflammatory drugs on the equine intestine. Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in the management of pain and endotoxaemia associated with colic in the horse. While NSAIDs effectively treat the symptoms of colic, there is evidence to suggest that their administration is associated with adverse gastrointestinal effects including right dorsal colitis and inhibition of mucosal barrier healing. Several studies have examined the pathophysiology of NSAID associated effects on the large and small intestine in an effort to avoid these complications and identify effective alternative medications. Differences in the re...
Plasma atrial natriuretic peptide concentrations in horses with heart disease: a pilot study. Atrial natriuretic peptide (ANP) is a cardiovascular biomarker that might be useful in assessing the severity of cardiac disease in horses. Plasma ANP concentrations (Cp(ANP)) were compared between horses with heart disease but normal chamber size and function (Group A; n=6), horses with heart disease associated with left atrial (LA) enlargement, LA dysfunction, and/or left ventricular (LV) enlargement (Group B; n=5), and horses with no clinically apparent cardiovascular disease (Group C; n=13). The median (min-max) for Cp(ANP) was significantly higher in Group B (53.5 (36.0-70.7) pg/mL), comp...
Characterization of the responses of equine digital veins and arteries to calcitonin gene-related peptide. To compare responses of equine digital arteries (EDAs) and veins (EDVs) to human-αcalcitonin gene-related peptide (hαCGRP), evaluate effect of the endothelium, and characterize receptors and sources of endogenous CGRP. Methods: Palmar digital vessels (5 to 9/experiment) from healthy adult horses killed at an abattoir. Methods: Vessel rings were mounted under tension in organ baths containing Krebs-Henseleit solution at 30 °C, with relaxation responses examined in vessels preconstricted with a thromboxane-mimetic (3 × 10(-8)M). Responses of endothelium-intact (+e) and -denuded (-e) EDAs and...
Nociceptive trigeminal reflexes in non-sedated horses. Electrically induced reflexes can be used to investigate the physiology and pathophysiology of the trigeminal system in humans. Similarly, the assessment of the trigemino-cervical (TCR) and blink reflexes (BR) may provide a new diagnostic tool in horses. The aim of this study was to evoke nociceptive trigeminal reflexes and describe the electrophysiological characteristics in non-sedated horses. The infraorbital (ION) and supraorbital nerves (SON) were stimulated transcutaneously in 10 adult Warmblood horses in separate sessions using train-of-five electrical pulses. The current was increased ...
Experimental mild pulmonary inflammation promotes the development of exercise-induced pulmonary haemorrhage. Histological studies of exercise-induced pulmonary haemorrhage (EIPH) reveals inflammatory infiltrates within areas of lung that contain haemorrhage. This has resulted in the hypothesis that pulmonary inflammation could cause EIPH or contribute to an increased risk or severity of EIPH. Objective: To determine whether experimentally-induced pulmonary inflammation predisposes the lung to haemorrhage during exercise, by evaluating the bronchoalveolar lavage (BAL) cytology of normal and inflamed regions of lung following high speed treadmill exercise. Methods: Transendoscopic airway inoculations o...
Effects of acute hyperinsulinemia on inflammatory proteins in horses. Laminitis is a painful, inflammatory disease of the equine hoof that often results in euthanasia. Elevated plasma insulin concentrations are a predictive factor for laminitis, and in previously healthy horses and ponies, laminitis was induced by infusion of insulin. Thus, we chose to determine if an infusion of insulin would increase plasma concentrations of inflammatory cytokines and cytokine mRNA abundance in subcutaneous adipose tissue, skeletal muscle, and white blood cells. Ten mature Thoroughbred mares received an insulin infusion that elevated plasma insulin concentrations for 6h or an ...
[Molecular basis and applicability in equine color genetics]. Coat color can be used not only in identifying individuals and species, but also in diagnosing certain diseases. The coat color of horse mainly depends on the distribution and proportion of eumelanin and phaeomelanin, generated by melanocytes, which are regulated by the genes such as MC1R, ASIP, KIT, TYRP, and EDNRB. In addition, STX17, MATP, and PMEL17 also play a role in the formation of coat color of horse. In this review, the action mechanism of candidate genes for coat color and association of DNA sequence polymorphism of these candidate genes with color pattern phenotypes and melanoma we...
Effects of endotoxin and influence of cyclooxygenase-2 on β-adrenergic mediated relaxation in isolated equine digital artery. The effects of endotoxin on β-adrenergic-mediated relaxation were investigated in the equine digital artery (EDA). Possible involvement of cyclooxygenase-2 (COX-2) in endotoxin-induced effects and basal EDA β-adrenoceptor functionality was also evaluated. Endothelium-intact (e(+)) and/or -denuded (e(-)) EDA rings were incubated overnight with lipopolysaccharide (LPS), LPS+NS398 (selective COX-2 inhibitor) or NS398 alone. Vessel rings were then mounted in organ baths and relaxant responses to isoproterenol (ISOP) recorded on U44069-induced pre-contraction. Response to ISOP was further evaluat...
Acute kidney injury mediated by oxidative stress in Egyptian horses with exertional rhabdomyolysis. The present study was carried out to evaluate the role of oxidative stress in the pathophysiologic process of acute renal failure associated with exertional rhabdomyolysis (ER) in Egyptian horses. ER was tentatively diagnosed in 31 Baladi horses based on case history, physical examination findings and confirmed by elevation of plasma creatine kinase (CK) and urine myoglobin concentrations. According to severity of the condition, the diseased horses were categorized into two main groups; the first group included 18 horses with minimal clinical signs and plasma CK 100 000 IU/L). It was found tha...
