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.
Stokes SM, Bertin FR, Stefanovski D, Poulsen L, Belknap JK, Medina-Torres CE, Pollitt CC, van Eps AW.Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycaemic hyperinsulinaemic clamp (EHC) and oligofructose (OF) laminitis models, but the mechanisms remain unclear. Objective: To evaluate the effects of CDH on lamellar energy metabolism and perfusion in healthy horses and during EHC and OF laminitis models. Methods: In vivo experiment. Methods: Archived samples were used from Standardbred geldings that received no treatment (CON) (n = 8) or underwent EHC (n = 8) or OF (n = 6) laminitis models. Both forelimbs were instrumented with a lamellar microdialysis system, a...
Wilson ME, McCandless EE, Olszewski MA, Robinson NE.Because the alveolar macrophage (AM) phenotype of horses with severe equine asthma (SEA) is unknown, the cytokines expressed by M1- and M2-polarized AM were determined and the hypothesis that natural hay/straw challenge (NC) induces divergent AM phenotypes in control horses and horses with SEA was tested. Macrophages from control horses were activated either with eIFNγ + lipolysaccharide (LPS) or eIL-4 to characterize M1- or M2-polarized AM gene expression, respectively and determine the response of polarized cells to pathogen-associated molecular patterns (PAMPS): LPS, zymosan, peptidoglycan...
equine sarcoids are the most frequent skin tumors in equidae worldwide. It is well known that delta bovine papillomaviruses are their causative agents. We have recently shown the presence in equine sarcoids of abnormal vessel structures, which could cause a hypoxic condition. The aim of this study was to analyze the expression of hypoxia-inducible factor-1 alpha (HIF-1α) in a subset of BPV positive equine sarcoids and explore the relationship with vascular endothelial growth factor (VEGF) expression. Results: 80% of equine sarcoids showed strong cytoplasmic staining in >60% of neoplastic f...
Durgam SS, Altmann NN, Coughlin HE, Rollins A, Hostnik LD.There is increased incidence of tendon disorders and decreased tendon healing capacity in people with diabetes mellitus (DM). Recent studies have also suggested pathological ossification in repair tendon of people with DM. Therefore, the objective of this study is to investigate the effects of insulin supplementation, an important pathophysiologic stimulus of DM, on tendon progenitor cell (TPC) proliferation and in vitro osteogenic capacity. Passage 3 TPCs were isolated from collagenase-digested, equine superficial digital flexor tendons. TPC proliferation was measured via MTT assay after 3 da...
Cuevas-Ramos G, Domenech L, Prades M.Postoperative reflux (POR) is a well-recognized complication after colic surgery in horses, particularly when presenting small intestinal pathology. Even though much has been written about the pathophysiology and management of POR, additional clinical studies are needed to better understand and anticipate this complication. The aim of the study was to provide clinical evidence of ultrasound findings in the postoperative period (three days). The study is based on transcutaneous abdominal ultrasounds of the caudoventral abdomen during the postoperative period (three days), in 58 horses, presente...
Chiaradia E, Pepe M, Orvietani PL, Renzone G, Magini A, Sforna M, Emiliani C, Di Meo A, Scaloni A.Osteochondrosis is a failure of the endochondral ossification that affects developing joints in humans and several animal species. It is a localized idiopathic joint disorder characterized by focal chondronecrosis and growing cartilage retention, which can lead to the formation of fissures, subchondral bone cysts, or intra-articular fragments. Osteochondrosis is a complex multifactorial disease associated with extracellular matrix alterations and failure in chondrocyte differentiation, mainly due to genetic, biochemical, and nutritional factors, as well as traumas. This study describes the mai...
de Laat MA, Spence RJ, Sillence MN, Pollitt CC.Equine laminitis is a disease of the digital epidermal lamellae typified by epidermal cell proliferation and structural collapse. Most commonly the disease is caused by hyperinsulinemia, although the pathogenesis is incompletely understood. Insulin can activate the epidermal growth factor (EGF) system in other species and the present study tested the hypothesis that upregulation of EGF receptor (EGFR) signalling is a key factor in laminitis pathophysiology. First, we examined lamellar tissue from healthy Standardbred horses and those with induced hyperinsulinemia and laminitis for EGFR distrib...
Ribitsch I, Gueltekin S, Keith MF, Minichmair K, Peham C, Jenner F, Egerbacher M.Aging is hypothesized to be associated with changes in tendon matrix composition which may lead to alteration of tendon material properties and hence propensity to injury. Altered gene expression may offer insights into disease pathophysiology and thus open new perspectives toward designing pathophysiology-driven therapeutics. Therefore, the current study aimed at identifying naturally occurring differences in tendon micro-morphology and gene expression of newborn, young and old horses. Age-related differences in the distribution pattern of tendon fibril thickness and in the expression of the ...
Hansen S, Otten ND, Birch K, Skovgaard K, Hopster-Iversen C, Fjeldborg J.The pathophysiology of equine asthma (EA) is still not fully described, but the involvement of an allergic reaction is strongly suspected. This theory has led to the use of allergen-specific immunoglobulin (Ig)E tests to support a diagnosis of asthma. The objective of this descriptive study was to evaluate the correlation between four subgroups of EA (mastocytic mild equine asthma [MEA], neutrophilic MEA, mixed MEA, and severe equine asthma [SEA]), allergen specific IgE (measured in both serum and BALF) and mRNA expression of selected genes in bronchoalveolar lavage fluid (BALF). Serum and BAL...
Espinosa G, Plaza A, Schenffeldt A, Alarcón P, Gajardo G, Uberti B, Morán G, Henríquez C.Polymorphonuclear neutrophils (PMN) are the largest leukocyte population in the blood of most mammals including horses, and play an important defensive role in many infectious diseases. However, the mechanisms that increase PMN as one of the main cellular subsets in the defense against pathogens could also be involved in the pathophysiology of dysregulated inflammatory conditions. Mesenchymal stem/stromal cells (MSCs) are a heterogeneous population with a modulatory potential on the inflammatory response and are known to interact with nearly all cells of the immune system, including PMN. In th...
Abs V, Bonicelli J, Kacza J, Zizzadoro C, Abraham G.Interaction between epithelial cells and fibroblasts play a key role in wound repair and remodelling in the asthmatic airway epithelium. We present the establishment of a co-culture model using primary equine bronchial epithelial cells (EBECs) and equine bronchial fibroblasts (EBFs). EBFs at passage between 4 and 8 were seeded on the bottom of 24-well plates and treated with mitomycin C at 80% confluency. Then, freshly isolated (P0) or passaged (P1) EBECs were seeded on the upper surface of membrane inserts that had been placed inside the EBF-containing well plates and grown first under liquid...
Bullone M, Lavoie JP.Human asthma is a complex and heterogeneous disorder characterized by chronic inflammation, bronchospasm and airway remodeling. The latter is a major determinant of the structure-function relationship of the respiratory system and likely contributes to the progressive and accelerated decline in lung function observed in patients over time. Corticosteroids are the cornerstone of asthma treatment. While their action on inflammation and lung function is well characterized, their effect on remodeling remains largely unknown. An important hindrance to the study of airway remodeling as a major focu...
Unterköfler MS, McGorum BC, Milne EM, Licka TF.In horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. The perfusion of isolated organs is successfully used to minimize animal testing for the study of pathophysiology in other scenarios. However, extracorporeal perfusion of equine ileum sourced from horses slaughtered for meat production has not yet been described. Therefore the pre...
Fretheim-Kelly ZL, Halvorsen T, Clemm H, Roksund O, Heimdal JH, Vollsæter M, Fintl C, Strand E.Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac diseas...
Cercone M, Olsen E, Perkins JD, Cheetham J, Mitchell LM, Ducharme NG.Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nin...
Hesselkilde EZ, Carstensen H, Flethøj M, Fenner M, Kruse DD, Sattler SM, Tfelt-Hansen J, Pehrson S, Braunstein TH, Carlson J, Platonov PG....Large animal models are important in atrial fibrillation (AF) research, as they can be used to study the pathophysiology of AF and new therapeutic approaches. Unlike other animal models, horses spontaneously develop AF and could therefore serve as a bona fide model in AF research. We therefore aimed to study the electrical, functional and structural remodelling caused by chronic AF in a horse model. Nine female horses were included in the study, with six horses tachypaced into self-sustained AF and three that served as a time-matched sham-operated control group. Acceleration in atrial fibrilla...
Sheats MK, Davis KU, Poole JA.Farmers are routinely exposed to organic dusts and aeroallergens that can have adverse respiratory health effects including asthma. Horses are farm-reared large animals with similar exposures and can develop equine asthma syndrome (EAS). This review aims to compare the etiology, pathophysiology, and immunology of asthma in horses compared to farmers and highlights the horse as a potential translational animal model for organic dust-induced asthma in humans. Severe EAS shares many clinical and pathological features with various phenotypes of human asthma including allergic, non-allergic, late o...
Draper ACE, Cahalan SD, Goodwin D, Perkins J, Piercy RJ.Equine recurrent laryngeal neuropathy (RLN) is a naturally occurring model of length-dependent axonopathy characterized by asymmetrical degeneration of recurrent laryngeal nerve axons (RLn). Distal RLn degeneration is marked, but it is unclear whether degeneration extends to include cell bodies (consistent with a neuronopathy). With examiners blinded to RLN severity, brainstem location, and side, we examined correlations between RLN severity (assessed using left distal RLn myelinated axon count) and histopathological features (including chromatolysis and glial responses) in the nucleus ambiguu...
Kemper AM, Drnevich J, McCue ME, McCoy AM.Skeletogenesis is complex and incompletely understood. Derangement of this process likely underlies developmental skeletal pathologies. Examination of tissue-specific gene expression may help elucidate novel skeletal developmental pathways that could contribute to disease risk. Our aim was to identify and functionally annotate differentially expressed genes in equine neonatal and adult articular cartilage (AC) and subchondral bone (SCB). RNA was sequenced from healthy AC and SCB from the fetlock, hock, and stifle joints of 6 foals (≤4 weeks of age) and six adults (8-12 years of age). There w...
Meyers S, Bulkeley E, Foutouhi A.The biological nature of age-related declines in fertility in males of any species, including stallions, has been elusive. In horses, the economic costs to the breeding industry are frequently extensive. Mitochondrial function in ejaculated sperm, which is essential for sperm motility, is reflected by adenosine triphosphate production, mitochondrial oxidative efficiency and production of reactive oxygen species, and that this balance may become compromised in ageing stallions and during the process of cryopreservation. This presentation will focus on mitochondrial integrity and function as an ...
Stewart AJ, Hackett E, Bertin FR, Towns TJ.Plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations increase with illness-associated stress. Dynamics of plasma ACTH and serum cortisol concentrations in adult horses with systemic illness are undocumented. Objective: To determine whether ACTH and cortisol concentrations and the ACTH/cortisol ratio vary with survival, the presence of systemic inflammatory response syndrome (SIRS), or ischemic gastrointestinal lesions at admission, or throughout hospitalization. Methods: One hundred fifty-one adult horses. Methods: Prospective study measuring serum cortisol and plasma AC...
Aleman M, McCue PM, Chigerwe M, Madigan JE.Transient hypothalamic-pituitary-adrenal axis dysfunction occurs in critically ill foals with sepsis and neonatal maladjustment syndrome (NMS). Cortisol is the most commonly measured steroid. However, a complex interaction of various steroid compounds might play a role in pathophysiology of this disorder. Objective: To identify steroid compounds present at high concentrations at birth that rapidly and steadily decrease within the first 7 days of life in healthy foals and that might be supportive diagnosis of NMS and other neonatal disorders. Methods: Ten healthy neonatal Quarter Horse foals ...
Fintl C, Lindberg R, McL Press C.Inflammatory bowel disease (IBD) is a well-recognised but poorly understood disease complex in the horse. Clinical signs may vary but often include weight loss, diarrhoea and colic. The effect this disease process may have on the gastrointestinal pacemaker cells (the interstitial cells of Cajal), enteric neurons and glial cells has not been previously evaluated in the horse. Objective: To compare the density of the interstitial cells of Cajal (ICC), enteric neurons and glial cells in horses with IBD to those of normal horses using immunohistochemical markers. Methods: Retrospective, quantitati...
Vera L, Campos Arias D, Muylle S, Stergiopulos N, Segers P, van Loon G.Arterial rupture in horses has been observed during exercise, after phenylephrine administration or during parturition (uterine artery). In human pathophysiological research, the use of computer models for studying arterial hemodynamics and understanding normal and abnormal characteristics of arterial pressure and flow waveforms is very common. The objective of this research was to develop a computer model of the equine arterial circulation, in order to study local intra-arterial pressures and flow dynamics in horses. Morphologically, large differences exist between human and equine aortic arc...
Rosser J, Bachmann B, Jordan C, Ribitsch I, Haltmayer E, Gueltekin S, Junttila S, Galik B, Gyenesei A, Haddadi B, Harasek M, Egerbacher M, Ertl P....In this work, we describe a microfluidic three-dimensional (3D) chondrocyte culture mimicking in vivo articular chondrocyte morphology, cell distribution, metabolism, and gene expression. This has been accomplished by establishing a physiologic nutrient diffusion gradient across the simulated matrix, while geometric design constraints of the microchambers drive native-like cellular behavior. Primary equine chondrocytes remained viable for the extended culture time of 3 weeks and maintained the low metabolic activity and high Sox9, aggrecan, and Col2 expression typical of articular chondrocytes...
Gómez-Torres FA, Ballesteros-Acuña LE, Ruíz-Sauri A.The cardiac nodes are the source of the electrical impulse that is transmitted to the heart, the aim of this work is study the histological and morphometric characteristics of the different components of the sinus and atrioventricular nodes in horses and dogs that help to know the physiopathology of these nodes. A group of ten horse hearts and five dog hearts were used. The region of the sinus and atrioventricular nodes was sectioned serially, and the block of tissue removed for study. The samples were assessed using a morphometric analysis with the Image-Pro Plus 7.1 software and the acquisit...
Martínez-Boví R, Zagrajczuk A, Donadeu FX, Skarzynski DJ, Piotrowska-Tomala K, Cuervo-Arango J.Haemorrhagic anovulatory follicles (HAFs) are the most common pathological anovulatory condition in the mare. To enhance understanding of the physiopathology of HAFs, the aim of the present study was to determine the effects of an induced-follicular wave on LH concentrations and follicular fluid factors relevant to the ovulatory process. Mares were allocated to treatment or control groups (n = 7/group) in a crossed over design during 14 oestrous cycles with a period of one cycle occurring when there were no treatments between the times when treatments were administered. In the treatment gr...
Banse HE, Andrews FM.Equine glandular gastric disease (EGGD) is an increasingly recognized disease of the glandular mucosa of the equine stomach. Diagnosis is confirmed by gastric endoscopy and scored based upon one of several different endoscopic scoring systems. Prevalence appears to be variable, depending upon breed and discipline. Primary identified risk factors include exercise frequency, and stress; therefore, management strategies are focused on reducing exercise and stress. Limiting grain intake and increasing pasture turnout may also be helpful preventative measures. Pharmacologic treatment consists prima...
Nykänen O, Sarin JK, Ketola JH, Leskinen H, Te Moller NCR, Tiitu V, Mancini IAD, Visser J, Brommer H, van Weeren PR, Malda J, Töyräs J, Nissi MJ.To investigate the potential of quantitative susceptibility mapping (QSM) and T2* relaxation time mapping to determine mechanical and structural properties of articular cartilage via univariate and multivariate analysis. Samples were obtained from a cartilage repair study, in which surgically induced full-thickness chondral defects in the stifle joints of seven Shetland ponies caused post-traumatic osteoarthritis (14 samples). Control samples were collected from non-operated joints of three animals (6 samples). Magnetic resonance imaging (MRI) was performed at 9.4 T, using a 3-D multi-echo gr...
Leise B.Equine laminitis is a devastating disease in which failure of the adhesion between the digital dermal and epidermal laminae at the basement membrane results in crippling lameness and structural damage to the foot of the horse. Laminitis occurring secondary to sepsis is known to result from a significant inflammatory response that includes leukocyte emigration into the lamellar tissue. These leukocytes, in particular the neutrophil, have been extensively evaluated in experimental models of sepsis-related laminitis in the horse. This review will discuss the relevant findings elucidated from thes...
Malalana F, Blundell RJ, Pinchbeck GL, Mcgowan CM.Equine recurrent uveitis (ERU) is a common cause of ocular pain and blindness in horses. Leptospira spp. have been commonly implicated in the pathophysiology of ERU in mainland Europe and the USA. No recent studies have been carried out in the UK, but Leptospira is reported not to be a major factor in the aetiology of ERU in the UK. Objective: To establish the prevalence of Leptospira-associated ERU in the UK and to identify the serovars involved in these cases; to compare serum vs. aqueous humour antibody levels in cases and controls in order to confirm the diagnosis of Leptospira-associated ...
Divers TJ, Mohammed HO, Cummings JF, Valentine BA, De Lahunta A, Jackson CA, Summers BA.Over a three and one-half year period, 28 adult horses were diagnosed with equine motor neuron disease (EMND). The most commonly identified environmental risk factors for a horse having EMND were absence of grazing for more than a year and provision of poor quality hay. Quarter Horses were 5.4 times more at risk than other breeds but this was thought to be an epiphenomenon related to the frequency of Quarter Horses at boarding stables. Weight loss, excessive recumbency and/or trembling were the first signs noted. Other clinical diagnostic signs included: constant shifting of the weight in the ...
Delarocque J, Frers F, Feige K, Huber K, Jung K, Warnken T.Little is known about the implications of hyperinsulinemia on energy metabolism, and such knowledge might help understand the pathophysiology of insulin dysregulation. Objective: Describe differences in the metabolic response to an oral glucose test, depending on the magnitude of the insulin response. Methods: Twelve Icelandic horses in various metabolic states. Methods: Horses were subjected to 3 oral glucose tests (OGT; 0.5 g/kg body weight glucose). Basal, 120 and 180 minutes samples were analyzed using a combined liquid chromatography tandem mass spectrometry and flow injection analysis ...
Teixeira RB, Rendahl AK, Anderson SM, Mickelson JR, Sigler D, Buchanan BR, Coleman RJ, McCue ME.Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses. Objective: To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population. Methods: A total of 335 gray QH with and without dermal melanomas. Methods: Blood or hair roo...
De Cock HE, Affolter VK, Farver TB, Van Brantegem L, Scheuch B, Ferraro GL.Chronic progressive lymphedema in Clydesdale and Shire draft horses causes severe disability of the limbs which leads to premature death of these horses. Since appropriate function of lymph vessels is dependent on the presence of viable elastin fibers, the goal of this study was to document differences in skin elastin fibers in affected horse breeds, compared to a nonaffected draft horse breed. Results: Biochemical analysis of cutaneous desmosine, a cross-linking amino acid found only in elastin, was used to measure elastin in the skin from 110 draft horses. This included 7 normal, 38 mildly a...
Linardi RL, Megee SO, Mainardi SR, Senoo M, Galantino-Homer HL.The limited characterization of equine skin, eye and hoof epithelial stem cell (ESC) and differentiation markers impedes the investigation of the physiology and pathophysiology of these tissues. Objective: To characterize ESC and differentiation marker expression in epithelial tissues of the equine eye, haired skin and hoof capsule. Methods: Indirect immunofluorescence microscopy and immunoblotting were used to detect expression and tissue localization of keratin (K) isoforms K3, K10, K14 and K124, the transcription factor p63 (a marker of ESCs) and phosphorylated p63 [pp63; a marker of ESC tr...
Garcia T, Hornof WJ, Insana MF.The strong dependence of tendon echogenicity on insonation angle is explored by analyzing echo spectra. Combining echo spectra with high-resolution images from several modalities reveals that fluid spaces surrounding fascicles and bundles are likely sources of ultrasonic scatter. Mathematical models of tendon structure are proposed to explain how the anisotropic microstructure of tendon gives rise to angle-dependent echogenicity. Echo spectra from spontaneously damaged equine tendon samples were compared with normal equine tendon and found to exhibit a dramatic decrease in anisotropic properti...
Williams ZJ, Velez-Irizarry D, Gardner K, Valberg SJ.Myofibrillar myopathy in humans causes protein aggregation, degeneration, and weakness of skeletal muscle. In horses, myofibrillar myopathy is a late-onset disease of unknown origin characterized by poor performance, atrophy, myofibrillar disarray, and desmin aggregation in skeletal muscle. This study evaluated molecular and ultrastructural signatures of myofibrillar myopathy in Warmblood horses through gluteal muscle tandem-mass-tag quantitative proteomics (5 affected, 4 control), mRNA-sequencing (8 affected, 8 control), amalgamated gene ontology analyses, and immunofluorescent and electron m...
Kirkwood NC, Hughes KJ, Stewart AJ.Substantial morbidity results from pituitary pars intermedia dysfunction (PPID) which is often underestimated by owners and veterinarians. Clinical signs, pathophysiology, diagnostic tests, and treatment protocols of this condition are reviewed. The importance of improved recognition of early clinical signs and diagnosis are highlighted, as initiation of treatment will result in improved quality of life. Future research should be targeted at improving the accuracy of the diagnosis of PPID, as basal adrenocorticotropic hormone (ACTH) concentration can lack sensitivity and thyrotropin releasing ...
Hosaka Y, Kirisawa R, Ueda H, Yamaguchi M, Takehana K.Tumor necrosis factor (TNF) receptors (TNF-R)-mediated cell survival or apoptosis has been demonstrated in many cells, but little is known about survival or apoptotic signals via TNF-R1 in tendinocytes. In this study, we focused on four signaling factors, TNFalpha, TNF-R1, TNFR-associated factor2 (TRAF2) and caspase-3, in order to elucidate the signaling events in tendinocytes. Samples were obtained from normal, inflamed and scar-formed equine superficial digital flexor tendons. To detect these signaling factors, samples were subjected to immunohistochemistry and Western blot analysis, and som...
Stadler P, Deegen E.Dynamic compliance, airway resistance, viscous work and respiratory frequency were measured at intervals in horses over 12 h periods. Variation, daily averages and circadian patterns were recorded. Examinations were performed on 24 horses. They were divided into three groups: Normal horses, horses with chronic latent bronchitis and horses with manifest chronic obstructive pulmonary disease (COPD). Significant differences were found between the daily averages and the fluctuations when the normal group and the COPD group were compared. In most cases differences between all three groups were sign...
Mazan MR, Hoffman AM, Manjerovic N.To compare response of horses to histamine bronchoprovocation (HBP), using total respiratory resistance (Rrs) measured by forced oscillatory mechanics (FOM) with dynamic compliance (Cdyn) and pulmonary resistance (RL) measured by the esophageal balloon method. Methods: 10 horses with various degrees of airway reactivity. Methods: The 2 methods for measuring airway responses to HBP were performed on separate days. Endpoints compared were increase of 150 or 200% of baseline Rrs (PC150Rrs, PC200Rrs) and to 150% of baseline RL (PC150RL) or decrease to 65% of baseline Cdyn (PC65Cdyn). Frequency dep...
Morgan RA, Keen JA, Walker BR, Hadoke PW.Endocrinopathic laminitis (EL) is a vascular condition of the equine hoof resulting in severe lameness with both welfare and economic implications. EL occurs in association with equine metabolic syndrome and equine Cushing's disease. Vascular dysfunction, most commonly due to endothelial dysfunction, is associated with cardiovascular risk in people with metabolic syndrome and Cushing's syndrome. We tested the hypothesis that horses with EL have vascular, specifically endothelial, dysfunction. Healthy horses (n = 6) and horses with EL (n = 6) destined for euthanasia were recruited. We studied v...
Waller AP, Huettner L, Kohler K, Lacombe VA.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...
Sykes BW, Furr MO.The pathophysiology of endotoxaemia, a leading cause of death in the horse, is beginning to be understood in greater detail. Endotoxin may be absorbed into the systemic circulation in a number of different ways: most commonly the body's normal defense mechanisms are disrupted or bypassed, or the normal clearance mechanisms overwhelmed. Following this wide-spread effects are observed, although the most significant are seen in the cardiovascular system. Fever, arterial hypoxaemia and signs of abdominal pain are also common. With increased understanding of the disease new therapeutic agents have ...
Strand E, Fjordbakk CT, Holcombe SJ, Risberg A, Chalmers HJ.Dynamic laryngeal collapse (DLC) associated with poll flexion is a newly diagnosed upper respiratory tract obstructive disorder that causes poor racing performance. Objective: To determine if Norwegian Coldblooded Trotters (NCTs) affected with DLC associated with poll flexion differ from normal, elite NCTs based on simple airway mechanics measurements. Methods: Five normal elite NCTs and 6 NCTs diagnosed previously with DLC underwent treadmill videoendoscopy while tracheal pressures were measured continuously. Alternating head positions were used such that horses were exercised with free head ...
Sisó S, Ferrer I, Pumarola M.Numerous swollen neurons and multiple dystrophic axons were observed in the gracillis and cuneatus nuclei of two male Arabian horses, aged six and 12 months of age, with equine degenerative myeloencephalopathy. Swollen neurons and dystrophic axons showed synaptophysin, synaptosomal-associated protein of 25 kDa, syntaxin-1 and alpha-synuclein immunoreactivity. Moreover, dystrophic axons were strongly immunopositive against the ubiquitin protein and against the anti-phosphorylated 200 kDa neurofilament protein. Abnormal expression of integral synaptic vesicle, synaptic vesicle-associated presyna...
Belknap JK.The black walnut extract (BWE) model was developed after the discovery that horses bedded on shavings from black walnut trees commonly developed laminitis. The first investigators that consistently induced laminitis with black walnut shavings established that it was only the heartwood of the tree that induced laminitis. The BWE model of laminitis has allowed investigators to determine many of the early pathologic signaling events likely to occur in the developmental and acute clinical stages of the disease process, and has brought inflammatory injury to the forefront of laminitis research. The...
Couëtil LL, Rosenthal FS, Simpson CM.The purpose of this study was to assess whether our method of inducing forced expiration detects small airway obstruction in horses. Parameters derived from forced expiratory flow-volume (FEFV) curves were compared with lung mechanics data obtained during spontaneous breathing in nine healthy horses, in three after histamine challenge, and in two with chronic obstructive pulmonary disease (COPD) pre- and posttherapy with prednisone. Parameters measured in the healthy horses included forced vital capacity (FVC = 41.6 +/- 5.8 liters; means +/- SD) and forced expiratory flow (FEF) at various perc...
Smith GW, Constable PD, Foreman JH, Eppley RM, Waggoner AL, Tumbleson ME, Haschek WM.To determine whether cardiovascular dysfunction is evident in horses with leukoencephalomalacia experimentally induced by administration of fumonisin B1. Methods: 11 healthy horses of various breeds (body weight, 252 to 367 kg). Methods: Horses were randomly assigned to 3 groups and administered fumonisin B1 daily. Horses received IV injections of 0 (control horses; n = 4), 0.01 (3), or 0.20 mg (4) of fumonisin B1/kg for 7 to 28 days. Horses were examined daily for evidence of neurologic disease. When neurologic signs consistent with leukoencephalomalacia were evident, horses were anesthetized...
Pozza ME, Kaewsakhorn T, Trinarong C, Inpanbutr N, Toribio RE.Vitamin D is essential in calcium and phosphorus regulation, bone physiology, cell proliferation and epithelial integrity. Literature on vitamin D in growing horses is sparse, and the effect of age on vitamin D has not been evaluated in equids in the United States or in tropical countries. The goal of this study was to determine if there was an effect of age on serum 25(OH)D3 concentrations in equids in the US (Ohio/Kentucky) and Thailand (Chiang Rai and Kanchanaburi) during the same time of the year. Blood samples were collected from healthy ponies (n=21) and Thoroughbred foals (n=13), yearli...
Mosing M, Waldmann AD, MacFarlane P, Iff S, Auer U, Bohm SH, Bettschart-Wolfensberger R, Bardell D.This study evaluated the breathing pattern and distribution of ventilation in horses prior to and following recovery from general anaesthesia using electrical impedance tomography (EIT). Six horses were anaesthetised for 6 hours in dorsal recumbency. Arterial blood gas and EIT measurements were performed 24 hours before (baseline) and 1, 2, 3, 4, 5 and 6 hours after horses stood following anaesthesia. At each time point 4 representative spontaneous breaths were analysed. The percentage of the total breath length during which impedance remained greater than 50% of the maximum inspiratory impeda...
Sørensen MA, Petersen LJ, Bundgaard L, Toft N, Jacobsen S.As in other fibroproliferative disorders, hypoxia has been suggested to play a key role in the pathogenesis of exuberant granulation tissue (EGT). The purpose of this study was to investigate metabolism and blood flow locally in full-thickness wounds healing with (limb wounds) and without (body wounds) formation of EGT. Microdialysis was used to recover endogenous metabolites from the wounds, and laser Doppler flowmetry was used to measure blood flow. Measurements were performed before wounding and 1-28 days after wounding. Blood flow was consistently lower in limb wounds than in body wounds t...
Hulliger MF, Pacholewska A, Vargas A, Lavoie JP, Leeb T, Gerber V, Jagannathan V.Severe equine asthma is an incurable obstructive respiratory condition affecting 10-15% of horses in temperate climates. Upon exposure to airborne antigens from hay feeding, affected horses show neutrophilic airway inflammation and bronchoconstriction, leading to increased respiratory effort. The resulting implications range from welfare concerns to economic impacts on equestrian sports and horse breeding. Immunological and pathophysiological characteristics of severe equine asthma show important parallels with allergic and severe neutrophilic human asthma. Our study aimed at investigating reg...
Cottrell DF, McGorum BC, Pearson GT.Autonomic dysfunction constitutes a prominent clinical feature of equine grass sickness (EGS). Significant injury to the nervous control of the alimentary system is life threatening, partly because of dysphagia but also because of the failure of the unique regulatory mechanisms in equine digestion involving water and electrolyte balance. The neuropathology also indicates the presence of a somatic polyneuropathy. The morphological features of EGS are similar to those of excitotoxic neuronal degeneration, which resembles neuronal apoptosis. It is difficult to ascertain from published accounts th...
Geor RJ.Epidemiologic studies indicate that most laminitis cases occur in horses and ponies kept at pasture, hence the term 'pasture-associated laminitis'. Clinical cases of laminitis most often occur under conditions that favor accumulation of rapidly fermentable nonstructural carbohydrates (fructans, simple sugars, or starches) in pasture, and animals with an equine metabolic syndrome (EMS) phenotype (insulin resistance, abnormal insulin dynamics, +/- obesity) seem to be at highest risk for developing the condition. Although the mechanisms linking consumption of pasture forage with development of la...
Hoffman AM, Oura TJ, Riedelberger KJ, Mazan MR.Horses with recurrent airway obstruction (heaves) are described as exhibiting "increased abdominal effort," but it is unknown whether this translates to an effective contribution to ventilation. Objective: We hypothesized that heaves is characterized by asynchrony between rib cage and abdominal motions, and that the abdominal component is the major contributor to ventilation. Methods: The rib cage versus abdominal motion in naturally occurring heaves (n = 15) was compared to controls at rest (n = 7) and during hyperpnea because of lobeline treatment, and the effects of histamine-induced bronch...
Sprouse RF, Garner HE, Green EM.Thirteen (65 per cent) of 20 horses subjected to carbohydrate overload developed Obel Grade 3 lameness within 56 h. Increases in plasma endotoxin from control levels of less than 0.1 ng/litre to values ranging from 2.4 to 81.53 ng/litre were measured in 11 (85 per cent) of 13 horses during the onset of Obel Grade 3 lameness. Obel Grade 3 lameness was associated with rises in plasma Gram-negative endotoxin levels in 11 (92 per cent) of 12 horses. Two peak increases separated by 16 h were verified in five (45 per cent) of 11 horses that exhibited both endotoxaemia and Obel Grade 3 lameness. The ...
