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.
Lacombe VA.Glucose uptake is the rate-limiting step in glucose utilization in mammalians and is tightly regulated by a family of specialized proteins, called the facilitated glucose transporters (GLUTs/SLC2). GLUT4, the major isoform in insulin-responsive tissue, translocates from an intracellular pool to the cell surface and as such determines insulin-stimulated glucose uptake. However, despite intensive research over 50 years, the insulin-dependent and -independent pathways that mediate GLUT4 translocation are not fully elucidated in any species. Insulin resistance (IR) is one of the hallmarks of equin...
Dakin SG, Dudhia J, Smith RK.Injuries to the superficial digital flexor tendon (SDFT) are an important cause of morbidity and mortality in equine athletes, but the healing response is poorly understood. One important drive for the healing of connective tissues is the inflammatory cascade, but the role of inflammation in tendinopathy has been contentious in the literature. This article reviews the processes involved in the healing of tendon injuries in natural disease and experimental models. The importance of inflammatory processes known to be active in tendon disease is discussed with particular focus on recent findings ...
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...
Pirie RS.Recurrent airway obstruction is a widely recognised airway disorder, characterised by hypersensitivity-mediated neutrophilic airway inflammation and lower airway obstruction in a subpopulation of horses when exposed to suboptimal environments high in airborne organic dust. Over the past decade, numerous studies have further advanced our understanding of different aspects of the disease. These include clarification of the important inhaled airborne agents responsible for disease induction, improving our understanding of the underlying genetic basis of disease susceptibility and unveiling the fu...
Shaba JJ, Behan Braman A, Robinson NE.In many inflammatory diseases plasma cortisol concentration (CORT) increases at the onset of acute inflammation, but the situation in recurrent airway obstruction (RAO) of horses is unknown. Methods: Split-plot repeated measures design with one grouping factor (disease) and two repeated factors (day and 3-hour intervals). Objective: To test the hypothesis that CORT increases as acute exacerbations of RAO develop. Methods: Four RAO-susceptible and 4 control horses were placed in a low dust environment (LDEnv) for 2 days followed by 2 days in a high dust environment (HDEnv). Exacerbations of RAO...
Williams MR, Arnoczky SP, Pease AP, Stick JA.To determine the microvascular anatomy of the suspensory ligament of the forelimb of horses. Methods: 17 cadaveric forelimbs from 9 adult horses with no known history of forelimb lameness. Methods: The median artery of the forelimb was cannulated proximal to the antebrachiocarpal joint and injected with contrast medium for CT evaluation of the gross vasculature (n = 2) or India ink to evaluate the microvasculature (12). Routine histologic evaluation was performed on an additional 3 forelimbs to confirm the microvascular anatomy. Results: The vascular supply of the suspensory ligament of the fo...
Hudson NP, Pearson GT, Mayhew IG, Proudman CJ, Burden FA, Fintl C.Intestinal motility disorders are an important problem in horses and donkeys and this study was carried out in order to evaluate the enteric neurons in animals with and without intestinal disease. Surplus intestinal tissue samples were collected from 28 horses undergoing exploratory laparotomy for colic. In addition, surplus intestinal samples from 17 control horses were collected immediately following humane destruction for clinical conditions not relating to the intestinal tract. Similar samples were also collected during routine post-mortem examinations from 12 aged donkeys; six animals wer...
Bergvall KE.Sarcoids are the most common skin tumors seen in horses worldwide. The pathogenesis of sarcoids is multifactorial, including an association with bovine papillomavirus types 1 and 2 and a genetic susceptibility to tumor development. Clinical manifestations vary and include occult, verrucous, nodular, fibroblastic, mixed, and malignant (malevolent) types. The tumor is nonmetastasizing but can become very aggressive locally. Multiple tumors are common. All clinical types can be present in the same horse. No treatment protocol is universally effective. The tumor has a high risk of recurrence. Recu...
de Graaf-Roelfsema E.One of the principal components of equine metabolic syndrome (EMS) is hyperinsulinaemia combined with insulin resistance. It has long been known that hyperinsulinaemia occurs after the development of insulin resistance. But it is also known that hyperinsulinaemia itself can induce insulin resistance and obesity and might play a key role in the development of metabolic syndrome. This review focuses on the physiology of glucose and insulin metabolism and the pathophysiological mechanisms in glucose homeostasis in the horse (compared with what is already known in humans) in order to gain insight ...
Aleman M, Williams DC, Brosnan RJ, Nieto JE, Pickles KJ, Berger J, Lecouteur RA, Holliday TA, Madigan JE.Idiopathic headshaking (HSK) in horses is a distressing disorder in which the etiology and pathophysiology are unknown. Objective: Differences in sensory function of the trigeminal nerve exist between healthy and affected horses. Methods: Six healthy mature geldings and 6 mature geldings with idiopathic HSK. Methods: Prospective study. Sensory nerve action and somatosensory evoked potentials studies were performed. The stimulus site comprised the gingival mucosa dorsal to the maxillary canine. A pair of recording electrodes was placed along the sensory pathway of the trigeminal complex at the ...
Decloedt A, de Clercq D, van der Vekens N, Verheyen T, van Loon G.Atrial fibrillation cycle length (AFCL) is an indicator of atrial electrical remodelling during atrial fibrillation (AF). Objective: To compare AFCL measured invasively from an intra-atrial electrogram (AFCLEGM ) with AFCL measured noninvasively by atrial colour tissue Doppler imaging (AFCLTDI ). Methods: Prospective descriptive clinical study. Methods: Measurements were performed in 31 episodes of AF or flutter in 29 horses (588 ± 61 kg bwt, 9 ± 3 years old) admitted for transvenous electrical cardioversion. The AFCLEGM was measured from an intracardiac electrogram using a bipolar sensi...
Bowser JE, Elder SH, Pasquali M, Grady JG, Rashmir-Raven AM, Wills R, Swiderski CE.Hereditary equine regional dermal asthenia (HERDA) is an autosomal recessive disorder of Quarter Horses characterised by skin fragility. Horses with HERDA have a missense mutation in peptidyl-prolyl cis-trans isomerase B (PPIB), which encodes cyclophilin B and alters folding and post translational modifications of fibrillar collagen. Objective: The study aimed to test the hypothesis that tendons, ligaments and great vessels, which, like skin, are rich in fibrillar collagen, will also have abnormal biomechanical properties in horses with HERDA. Methods: Ex vivo biomechanical study comparing...
Rendle DI, Litchfield E, Heller J, Hughes KJ.There is little published information on whether measurement of plasma ACTH concentration at a single timepoint is a repeatable indicator of pituitary pars intermedia dysfunction (PPID). Objective: To determine whether ultradian or circadian fluctuations in ACTH production influence plasma ACTH concentration in normal horses and horses with PPID. Methods: Prospective observational study. Methods: Plasma ACTH concentration in 8 non-PPID horses and 8 horses with PPID was measured at 08.00, 11.00, 14.00 and 17.00 h on 5 nonconsecutive days within a 3 week period. In addition, at 08.30 h on one da...
Peffers M, Liu X, Clegg P.Age is an important factor in the development of osteoarthritis. Microarray studies provide insight into cartilage aging but do not reveal the full transcriptomic phenotype of chondrocytes such as small noncoding RNAs, pseudogenes, and microRNAs. RNA-Seq is a powerful technique for the interrogation of large numbers of transcripts including nonprotein coding RNAs. The aim of the study was to characterise molecular mechanisms associated with age-related changes in gene signatures. Methods: RNA for gene expression analysis using RNA-Seq and real-time PCR analysis was isolated from macroscopicall...
Gross S, Wilms D, Krause J, Brezesinski G, Andrä J.Equine sarcoid is a topically accessible model for the evaluation of anticancer peptides acting by physical membrane disruption avoiding the complexity of a systemic application. We aim at evaluating and improving natural peptides for host defence as lead structures, where we focus on the cationic and amphipathic peptide NK-2. Cytotoxicity tests, fluorescence microscopy and a chip-based biosensor, which enabled real-time monitoring of cell metabolism, were applied. Cancer cell killing was dynamic with an initial phase of increased cellular respiration, followed by membrane destruction. NK-2 wa...
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...
Altamura G, Corteggio A, Nasir L, Yuan ZQ, Roperto F, Borzacchiello G.Equine sarcoids are skin tumours of fibroblastic origin affecting equids worldwide. Bovine papillomavirus type-1 (BPV-1) and, less commonly, type-2 are recognized as etiological factors of sarcoids. The transforming activity of BPV is related to the functions of its major oncoprotein E5 which binds to the platelet-derived growth factor β receptor (PDGFβR) causing its phosphorylation and activation. In this study, we demonstrate, by coimmunoprecipitation and immunoblotting, that in equine sarcoid derived cell lines PDGFβR is phosphorylated and binds downstream molecules related to Ras-mitoge...
Koblinger K, Hecker K, Nicol J, Wasko A, Fernandez N, Léguillette R.The bronchoalveolar lavage (BAL) procedure can return variable volumes of fluid, possibly depending on the presence of bronchial collapse during fluid aspiration and on the severity of lung inflammation. Objective: We tested the hypothesis that horses with bronchial collapse during BAL are at higher risk of having severe lung inflammation. Methods: Prospective field study. Methods: Bronchial collapse was graded using a new simple scoring method (0, 1 or 2) during a standardised BAL procedure in the field on 131 horses with normal, mild/moderate or severe lower airway inflammation on cytology o...
Haltmayer E, Reiser S, Schramel JP, van den Hoven R.The aim of the study was to show that changes in thoracoabdominal asynchrony (TAA) between quiet breathing and CO2-induced hyperpnoea can be used to differentiate between horses with healthy airways and those suffering from inflammatory airway disease (IAD) or recurrent airway obstruction (RAO). The level of TAA was displayed by the Pearson's correlation coefficient (PCC) of thoracic and abdominal signals, generated by respiratory ultrasonic plethysmography (RUP) during quiet breathing and hyperpnoea. Changes in TAA were expressed as the quotient of the PCCs (PCCQ) during normal breathing and ...
Decloedt A, Verheyen T, Van Der Vekens N, Sys S, De Clercq D, van Loon G.Atrial fibrillation (AF) causes atrial electrical and contractile remodelling in horses. The aim of this study was to quantify left atrial (LA) contractile function and its time course of recovery after cardioversion of naturally-occurring AF in horses. The study population included 42 AF horses which were successfully treated using transvenous electrical cardioversion TVEC (n=39) or quinidine sulfate (n=3), with trivial or mild mitral regurgitation present in 25 horses. Thirty-seven healthy horses were used as controls. AF duration was estimated based on the history and previous examinations....
Miller C, Utter ML, Beech J.To determine effects of age and pituitary pars intermedia dysfunction (PPID) on corneal sensitivity in horses. Methods: 20 adult horses allocated into 3 groups (PPID group, old [> 15 years old] horses with PPID [n = 5]; old group, old [> 15 years old] horses without PPID [9]; and young group, young [≤ 10 years old] horses without PPID [6]). All horses with PPID had hirsutism and abnormal fat deposition or laminitis; none of the old or young horses had hirsutism, abnormal fat deposition, or laminitis. Methods: A Cochet-Bonnet aesthesiometer was used to measure the corneal touch threshold (CTT...
Behan AL, Hauptman JG, Robinson NE.To use noninvasive respiratory inductance plethysmography (RIP) to investigate differences in breathing patterns between horses with and without recurrent airway obstruction (RAO) during the onset of airway obstruction induced through confinement to stables. Methods: 12 horses with no history or clinical signs of respiratory disease (control horses) and 7 RAO-affected horses. Methods: The study involved 2 phases. In phase 1, the optimal position of RIP bands for recording pulmonary function was investigated in 12 control horses. In phase 2, 7 RAO-affected and 7 control horses were confined to ...
Malekipour F, Whitton C, Oetomo D, Lee PV.Despite the important role of subchondral bone in maintaining the integrity of the overlying articular cartilage, little research has focused on measuring its mechanical behavior, particularly under injurious load conditions such as impact compression. In this study, the stiffness and the absorbed energy of subchondral bone were compared to that of its overlying cartilage by applying impact compression to equine cartilage-bone specimens. Deformations of the cartilage and subchondral bone were examined independently within the cartilage-bone unit by analyzing real-time images of cartilage-bone ...
Pusterla N, Gebhart CJ.Equine proliferative enteropathy (EPE) is a disease of foals caused by the obligate intracellular organism Lawsonia intracellularis. This emerging disease affects mainly weanling foals and causes fever, lethargy, peripheral oedema, diarrhoea, colic and weight loss. The diagnosis of EPE may be challenging and relies on the presence of hypoproteinaemia, thickening of segments of the small intestinal wall observed upon abdominal ultrasonography, positive serology and molecular detection of L. intracellularis in faeces. Although the clinical entity, diagnostic approach and treatment of EPE are w...
Sørensen MA, Jacobsen S, Petersen LJ.Microdialysis is a method for sampling compounds from extracellular fluid with minimal tissue trauma. Small hollow probes that are 0.2-0.5mm in diameter are inserted into the tissue and slowly perfused. The probe membrane is semi-permeable and a flux of the solutes occurs exclusively according to the concentration gradients. The recovered dialysate reflects changes in the composition of the extracellular water phase with a minor time delay. Because microdialysis is a continuous sampling method, it differs from point sample methods, such as blood sampling. The ability to obtain local measuremen...
Morlière P, Mazière JC, Patterson LK, Conte MA, Dupas JL, Ducroix JP, Filipe P, Santus R.Ferritin (Ft) impairment through (•)O2(-), H2O2, and (•)OH production occurs in the cases of ketoses, diabetes mellitus, acute intermittent porphyria and tyrosinemia. In addition to (•)Trp and TyrO(•) radical production, ferrous iron liberation and Ft synthesis stimulation, site-specific oxidation reactions are induced leading to toxic iron accumulation in organs with high Ft content, for example, liver and brain. To elucidate the potential pathways to Ft recovery, repair of oxidative damage to horse spleen apoferritin (apoFt) and Ft by quercetin (QH) or rutin (RH) was studied in the p...
Blong AE, Epstein KL, Brainard BM.To investigate the in vitro effects of 3 hydroxyethyl starch (HES) solutions on viscoelastic coagulation testing and platelet function in horses. Methods: Blood samples collected from 7 healthy adult horses. Methods: Blood samples were diluted with various crystalloid and HES solutions to approximate the dilution of blood in vivo that occurs with administration of a 10 and 20 mL/kg fluid bolus to a horse (1:8 and 1:4 dilutions, respectively). Diluted samples were analyzed through optical platelet aggregometry, platelet function analysis, thromboelastography, and dynamic viscoelastic coagulomet...
Pihl TH, Andersen PH, Kjelgaard-Hansen M, Mørck NB, Jacobsen S.Peritoneal fluid (PF) analysis is a valuable diagnostic tool in equine medicine. Markers such as serum amyloid A (SAA) and haptoglobin (Hp) could facilitate the diagnosis of inflammatory abdominal conditions. Objective: The objectives were to (1) establish reference intervals (RI) for SAA and Hp in serum and PF in healthy horses, (2) compare SAA and Hp concentrations between healthy horses and horses with colic, and (3) to assess the correlation between serum and PF concentrations. Methods: Serum amyloid A and Hp concentrations were determined by automated assays in prospectively enrolled heal...
Burns TA, Watts MR, Weber PS, McCutcheon LJ, Geor RJ, Belknap JK.Acute, massive enteral carbohydrate overload is associated with laminar inflammation in equids; it is unclear if the same is true for a more prolonged period of moderate dietary carbohydrate intake. Objective: To characterise laminar inflammation in ponies exposed to a dietary carbohydrate challenge meant to mimic acute pasture exposure. Methods: In vivo experiment. Methods: Mixed-breed ponies (n = 22) received a diet of hay chop (nonstructural carbohydrate [NSC] ∼7% on a dry matter [DM] basis) for 4 weeks prior to initiation of the experimental feeding protocol. Following dietary acclimatio...
Matera MG, Amorena M, Lucisano A.Equine obstructive pulmonary disease (COPD), or heaves or recurrent airway obstruction, is a common equine pulmonary disease similar to human asthma and/or CODP. Since bronchospasm and inflammation are the key features in heaves, the purpose of this paper is to review the contribution of neural mechanism that may be relevant to this disease. Equine airway receive cholinergic and adrenergic innervation, as well as observed in many species. It was suggested that the autonomic neural control in asthma might be defective with an imbalance between excitatory and inhibitory pathways, resulting in ex...
Sarcoids are the mostcommon skin tumors in horses, characterized by rare regression, invasiveness and high recurrence following surgical intervention and Delta Papillomaviruses are widely recognized as the causative agents of the disease. In order to gain new insights into equine sarcoid development, we have evaluated, in 25 equine sarcoids, by immunohistochemistry and western blotting analysis, the expression levels of VEGF, Ki67 and bcl-2. Moreover, we have measured microvessel density and specific vessel parameters. Results: All sarcoid samples showed a strong and finely granular cytoplasma...
Collins SN, Pollitt C, Wylie CE, Matiasek K.Laminitis poses a threat to all horses, and is widely considered as being one of the most important diseases of horses and a global equine welfare problem. The effects of laminitis lead to debilitation, development of pronounced digital pain, and great suffering in the afflicted animal. The precise pathophysiological processes that result in laminitic pain are poorly defined, and hence the delivery of effective palliative care is clinically challenging. Knowledge and understanding of pain states in other animal species may further aid the elucidation of equine laminitic pain mechanisms, guide ...
Ranjithkumar M, Malik TA, Saxena A, Dan A, Sakthivel PC, Dey S.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)...
Patteson MW, Cripps PJ.Auscultation was used to examine 545 horses for cardiac murmurs and some arrhythmias. The most significant finding was the high prevalence of right-sided holosystolic or pansystolic plateau-type murmurs compatible with a diagnosis of tricuspid regurgitation in National Hunt racing Thoroughbreds of all ages (16.4%). This condition was found in 4.7% of flat-racing Thoroughbreds, 3.7% of non-racing Thoroughbreds and Thoroughbred crosses, and in none of the ponies examined. High prevalences of left-sided early systolic murmurs (53%), left-sided early diastolic murmurs (23%), right-sided early dias...
Delesalle C, van de Walle GR, Nolten C, Ver Donck L, van Hemelrijck A, Drinkenburg W, de Bosschere H, Claes P, Deprez P, Lefere L, Torfs S....Increased plasma (5-HT) concentrations are reported in horses predisposed to develop laminitis and after i.v. infusion of endotoxins. In the equine jejunum contractile 5-HT1A-like receptors show tachyphylaxia upon prolonged activation with 5-HT. Therefore, increased systemic 5-HT release in colic horses could play a possible role in the pathophysiology of ileus. Objective: To investigate possible increased systemic release of 5-HT in colic horses with compromised bowel and to identify the source of 5-HT overload. Methods: Concentrations of 5-HT were determined in plasma and peritoneal fluid (P...
Howe DK, Yeargan M, Simpson L, Dangoudoubiyam S.Sarcocystis neurona is a member of the important phylum Apicomplexa and the primary cause of equine protozoal myeloencephalitis (EPM). Moreover, S. neurona is the best-studied species in the genus Sarcocystis, one of the most successful parasite taxa, as virtually all vertebrate animals may be infected by at least one species. Consequently, scientific investigation of S. neurona will aid in the control of EPM and neurologic disease in sea mammals, while also improving our understanding of a prominent branch on the apicomplexan phylogenetic tree. These protocols describe methods that expand the...
Toribio RE.Knowledge of urinary tract anatomy and the numerous functions of the kidney in regulating fluids, electrolytes, acid-base balance, and waste products improves the ability of the clinician to diagnose, treat, and make appropriate recommendations for the management of the horse with renal disease. Several conditions can directly or indirectly affect renal function on a temporary or permanent basis. Endogenous and exogenous compounds (eg, drugs, toxins, hemoglobin) alone or in combination with inappropriate renal blood flow can promote or exacerbate renal disease.
Buntenkötter S, Deegen E.Cardioversion through varying quinidine sulphate treatments was achieved in 3 riding horses with auricular fibrillation. The horses were subjected to continual telemetric ECG registration before and after reversion in a uniform exercise-tolerance-test. A comparison of the heart rate curves showed a strong decline of the heart beat frequency during the exercise phase after synchronisation. The decrease in heart rate during exercise was greater than 30% in all 3 patients. Anti-arrhythmic treatment is, therefore, recommended for horses with auricular fibrillation and without concurrent heart dise...
Rizzo A, Sciorsci RL.Homocysteine (Hcy) is a thiol-containing essential amino acid, important for the growth of cells and tissues. Several hypotheses exist regarding Hcy toxicity in humans; Hcy is involved in protein structural modifications, oxidative stress, and neurotoxicity induction and is therefore associated with several pathological conditions in humans. In veterinary science, knowledge regarding Hcy has increased recently due to several studies; however, many aspects remain undiscovered. Many details remain unknown regarding the effect of Hcy levels on pregnancy and the optimal management of pathological ...
Belknap JK.The treatment of laminitis has been fraught with confusion and controversy for several decades, mainly because of a lack of understanding of the pathophysiology of the disease process. However, recent advances in laminitis research have greatly improved our understanding of the disease process. This article discusses the various treatment options for laminitis in the context of the findings of recent scientific investigations of laminitis pathophysiology.
Marr CM, Reef VB, Reimer JM, Sweeney RW, Reid SW.Two-dimensional and M-mode echocardiograms were recorded from 41 horses before they were successfully treated for atrial fibrillation. In addition, these examinations were performed in a subgroup of 20 horses after treatment, and the results were compared with pretreatment values. Atrial fibrillation in this group of horses was associated with a reduction of mean left ventricular fractional shortening (mean 31% +/- 5.24%), and 22 of the 41 horses were below the reference range. The remaining mean M-mode variables were within the normal reference range, although 12 horses had increased left ven...
Dyson SJ, Arthur RM, Palmer SE, Richardson D.The gross and functional anatomy of the suspensory ligament (SL) and its ultrasonographic variability are described. Injuries of the suspensory apparatus are divided into lesions confined to the proximal one third of the metacarpus or metatarsus (proximal suspensory desmitis and avulsion fractures), lesions of the body, and branch lesions. Complete breakdown injuries are also discussed. In view of the close association of the SL, the second, third, and fourth metacarpal or metatarsal bones, and the proximal sesamoid bones, associated bony lesions are also considered.
Laverty S, Ionescu M, Marcoux M, Bouré L, Doizé B, Poole AR.The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C-propeptide of cartilage type-...
Bousquet-Mélou A, Formentini E, Picard-Hagen N, Delage L, Laroute V, Toutain PL.The present study aimed to characterize the adrenal response to ACTH. A model was developed that coupled the nonlinear disposition of cortisol with a physiologically based model for cortisol secretion by the adrenals. It was assumed that the response to ACTH resulted from two mechanisms: a stimulation of the cortisol secretion rate and control of the duration of the secretion. Seven dose levels of ACTH were tested in horses, a species similar to man as regards adrenal function. The main result was that the secretion rate of the adrenal gland can be modelized by a zero order process that is max...
Lavoie JP, Phan ST, Blais D.To evaluate the effects of detomidine and butorphanol in combination on respiratory function in horses and to determine whether these effects are more severe in horses with pre-existing respiratory dysfunction, Methods: Pulmonary function testing and arterial blood gas analyses were performed before and after administration of a combination of detomidine (10 micrograms/kg of body weight, i.v.) and butorphanol (20 micrograms/kg, i.v.). Methods: 5 horses with chronic obstructive pulmonary disease and 5 horses free of respiratory disease (controls). Methods: Flow rates were obtained from a pneumo...
Khanna AK, McDonell WN, Dyson DH, Taylor PM.The cardiopulmonary effects of eucapnia (arterial CO2 tension [PaCO2] 40.4 +/- 2.9 mm Hg, mean +/- SD), mild hypercapnia (PaCO2, 59.1 +/- 3.5 mm Hg), moderate hypercapnia (PaCO2, 82.6 +/- 4.9 mm Hg), and severe hypercapnia (PaCO2, 110.3 +/- 12.2 mm Hg) were studied in 8 horses during isoflurane anesthesia with volume controlled intermittent positive pressure ventilation (IPPV) and neuromuscular blockade. The sequence of changes in PaCO2 was randomized. Mild hypercapnia produced bradycardia resulting in a significant (P < 0.05) decrease in cardiac index (CI) and oxygen delivery (DO2), while ...
Eckert RE, Sharief Y, Jones SL.Equine laminar tissues do not contain resident neutrophils and have less superoxide dismutase (SOD) activity than other equine tissues, which makes them inherently more vulnerable to damage induced by reactive oxygen species (ROS) produced by neutrophils that enter the tissues. In the advanced clinical stages of acute laminitis, pathologic events in affected feet include a breakdown in the basement membrane, neutrophil infiltration, and platelet-neutrophil aggregates in laminar dermal veins, highlighting the contribution of neutrophils to the pathophysiology of the disease. The aim of this stu...
Smyth TT, Carmalt JL, Treen TT, Lanovaz JL.Diseases of the temporomandibular joint (TMJ) are well reported in man and some domestic animals other than the horse. The pathophysiology of equine TMJ disease and the effects of disease on the kinematics of mastication are unknown. Objective: To determine whether transient unilateral inflammation of the equine TMJ results in alterations in the masticatory cycle. Methods: An experimental controlled study utilising 6 horses of various ages with normal dentition. Methods: Each horse was equipped with an optical motion tracking (kinematic) system. Horses were observed chewing grass hay over 3 m...
Erickson BK, Seaman J, Kubo K, Hiraga A, Kai M, Yamaya Y, Wagner PD.In a previous study we evaluated the mechanism of alveolar-arterial PO2 (AaPO2) reduction when nitrogen is replaced with helium in normoxia (FIO2 = 0.21). The reduction in AaPO2 was not due to changes in VA/Q inequality, pulmonary O2 diffusing capacity, or cardiac output, but to more complete diffusion equilibration as a consequence of the higher ventilation and thus PAO2 (which reduced the average slope of the hemoglobin O2 dissociation curve (ODC), and thus enhanced diffusive equilibration). We hypothesized that hypoxic He/O2 breathing in contrast would not reduce the AaPO2 because PAO2 and ...
Bacci B, Stent AW, Walmsley EA.Lymphoma is the most common intestinal neoplasm in horses, but its clinical-pathological features are poorly characterized. Primary intestinal lymphoma was diagnosed in 20 horses on biopsy samples and further confirmed by postmortem examination in 16 cases. Lymphoma was found in the small intestine in 12 of 20 (60%), in the colon in 5 of 20 (25%), and in both small and large intestines in 3 of 20 (15%) cases. Gross findings included thickening of the intestinal wall (45%), mural nodules or masses (30%), and both thickening and nodules (10%). Cases were classified according to the human World H...
Hood DM, Wagner IP, Brumbaugh GW.To evaluate the use of hoof wall surface temperature (HWST) as an indirect indicator of digital perfusion and to describe HWST patterns during the prodromal and acute phases of carbohydrate-induced laminitis in horses. Methods: 30 adult horses without foot abnormalities. Methods: Three experiments were performed. In the first, HWST was measured in 2 groups of horses acclimatized to hot (n = 6), or cold (6) environments and exposed to cold (15 C) ambient temperature. In the second experiment, HWST were measured in both forefeet of 6 horses before and after application of a tourniquet to 1 foref...
Jean D, Vrins A, Lavoie JP.To determine temporal variations of pulmonary function in horses without respiratory tract disease (controls) and horses with chronic obstructive pulmonary disease (COPD) and determine whether reversibility of airway obstruction after environmental control can be predicted by response to atropine administration. Methods: 7 COPD-affected and 5 control horses. Methods: Pulmonary function testing was performed monthly during 3 consecutive months, daily for 5 consecutive days, and at 6-hour intervals for 24 hours before and after administration of atropine (0.02 mg/kg of body weight, i.v.) and aft...
du Preez S, Raidal SL, Doran GS, Prescott M, Hughes KJ.Exhaled breath condensate (EBC) analysis is a noninvasive method to assess the lower respiratory tract. In human subjects, EBC hydrogen peroxide (H O ), pH and leukotriene B (LTB ) are useful for detection and monitoring of inflammatory lung diseases, including asthma. Objective: To determine associations between EBC biomarkers and cytological and endoscopic definitions of lower airway inflammation (LAI) while controlling for sampling and environmental variables. Methods: Prospective, cross-sectional study. Methods: Clinical, endoscopic and airway cytological findings from 47 horses were compa...
Luethy D, Habecker P, Murphy B, Nolen-Walston R.Pheochromocytoma is the most common adrenal medullary neoplasm of domestic animals, but it is rare in horses. Antemortem diagnosis in horses is difficult, with clinical signs often being vague or non-specific. Objective: The objective of this study was to describe the clinical, laboratory, and pathologic findings of pheochromocytoma in horses. Methods: Thirty-seven horses diagnosed with pheochromocytoma based on postmortem examination from 2007 to 2014. Methods: Retrospective case series. Results: Pheochromocytoma was identified in 37/4094 horses during postmortem examination. Clinical signs c...
Manohar M, Goetz TE.Exercise-induced pulmonary hemorrhage (EIPH) is a common occurrence in racehorses. The objective of this study was to compare pulmonary vascular pressures of healthy Thoroughbred horses with and without postexertion endoscopically detectable fresh blood in the trachea. The nasopharynx, larynx, and trachea (down to the carina) of horses were examined weekly with an endoscope 55-60 min postexertion, and the diagnosis of EIPH was confirmed by the presence of fresh blood in the trachea. Measurements of heart rate and right atrial, pulmonary arterial, and pulmonary arterial wedge pressures were mad...
Reef VB, Spencer P.Echocardiographic evaluation of 23 horses with aortic insufficiency was performed, using M-mode (n = 23) and 2-dimensional real-time echocardiography (n = 14 of 23). Echocardiograms were evaluated for abnormalities of aortic and mitral valves and alterations in motion of these valves. Changes in left ventricular chamber size and function, as well as aortic root size, were evaluated. The presence of other cardiac disease was also evaluated. Horses with aortic insufficiency had significant increases (P less than 0.01) in mean values of left ventricular chamber size, aortic root diameter, and sho...
Hosaka YZ, Uratsuji T, Ueda H, Uehara M, Takehana K.This aim of this study was to determine the characteristic differences in tendinocytes derived from three sites of the equine superficial digital flexor tendon (SDFT)-proximally the myotendinous junction (MTJ), mid-metacarpal (mM) and osteotendinous junction (OTJ)-in morphology, proliferation, and ability for synthesis of collagen and matrix metalloproteinases (MMPs). Little difference was observed in cell proliferation. Addition of tumor necrosis factor (TNF) alpha to the culture medium resulted in increased collagen synthesis by tendinocytes from all three sites. The amount of collagen synth...
Fortin JS, Benskey MJ, Lookingland KJ, Patterson JS, Howey EB, Goudreau JL, Schott HC.Pituitary pars intermedia dysfunction (PPID) develops slowly in aged horses as degeneration of hypothalamic dopaminergic neurons leads to proliferation of pars intermedia (PI) melanotropes through hyperplasia and adenoma formation. Dopamine (DA) concentrations and tyrosine hydroxylase (TH) immunoreactivity are markedly reduced in PI tissue of PPID-affected equids and treatment with the DA receptor agonist pergolide results in notable clinical improvement. Thus, we hypothesized that pergolide treatment of PPID-affected horses would result in greater DA and TH levels in PI tissue collected from ...
