The equine cardiovascular system, particularly the heart, is fundamental to maintaining the health and performance of horses. The heart is responsible for pumping oxygenated blood throughout the body, supporting vital functions and physical activity. In horses, the heart's structure and function are adapted to meet the demands of both rest and exertion, with notable features such as a large cardiac output and efficient blood circulation. Conditions affecting the equine heart, such as arrhythmias, valvular diseases, and myocardial disorders, can significantly impact a horse's well-being and athletic capability. This page aggregates peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and pathophysiology of the equine heart, as well as diagnostic and therapeutic approaches to managing cardiac health in horses.
Williams NJ, Furr M, Navas de Solis C, Campolo A, Davis M, Lacombe VA.Metabolic syndrome in humans is commonly associated with cardiovascular dysfunction, including atrial fibrillation and left ventricular diastolic dysfunction. Although many differences exist between human and equine metabolic syndrome, both of these conditions share some degree of insulin resistance. The aims of this pilot study were to investigate the relationship between insulin sensitivity and cardiac function. Seven horses (five mares, two geldings, aged 17.2 ± 4.2 years, weight 524 ± 73 kg) underwent insulin-modified frequently sampled intravenous glucose tolerance testing to determine ...
Magalhaes HB, Canisso IF.Practitioners are frequently requested to diagnose and stage pregnancy in donkeys with unknown breeding dates; however, scant work has been done to stage pregnancy in the species. Therefore, this study aimed to determine the association between measurements of fetal aortic, thoracic, and heartbeat with gestational age in donkeys carrying and delivering healthy foals. Multiparous Dezhou donkeys (n = 50) ranging from 4 to 16 years were enrolled in the study by 150 days of gestation. Transabdominal ultrasonography coupled with a 3.5 MHz sectorial convex transducer was performed at 30 day-interv...
Eberhardt C, Schwarzwald CC.Focused cardiac ultrasound examination (FoCUS) is rapidly emerging for point-of-care cardiac assessment using hand-carried ultrasound (HCU) devices. A specific FoCUS protocol for horses and adequate training guidelines currently are not available. Objective: To gain knowledge about the training necessary to become proficient in performing FoCUS using a HCU device. Methods: Three healthy Warmblood horses were used for practical training of veterinarians and veterinary students in equine focused cardiac ultrasound (eFoCUS). Methods: Prospective educational study. An eFoCUS protocol and 1-day tra...
Vernemmen I, Paulussen E, Dauvillier J, Decloedt A, van Loon G.This case report describes the 2-dimensional transthoracic (2D-TTE), 3-dimensional transthoracic (3D-TTE) and intracardiac echocardiographic (ICE) characterization of the fossa ovalis region in 2 horses. The first case was presented for poor performance and showed an anechoic zone in the interatrial septum on 2D-TTE. Based on 3D-TTE a deepened fossa ovalis could be identified and using ICE the presence of an interatrial shunt could be excluded. The second case was referred for a cardiac murmur and the presence of turbulent flow in and around the interatrial septum on 2D-TTE color flow Doppler....
White A, Cullen P, Hinchion J.A stablehand in his 20s presented with increasing dyspnoea on exertion and chest pain months after being kicked directly in the chest by a horse. Further investigations revealed severe isolated, primary tricuspid regurgitation due to partial avulsion of the anterior leaflet. Open surgical repair was successfully performed from which he recovered uneventfully with resolution of his symptoms and minimal residual tricuspid regurgitation. Although uncommon, blunt force trauma to the chest is becoming increasingly recognised as a rare cause of tricuspid regurgitation. Symptoms may be insidious, and...
Nath L, Stent A, Elliott A, La Gerche A, Franklin S.Cardiac arrhythmias resulting in sudden cardiac death (SCD) are an important cause of racehorse fatalities. The objective of this study was to determine risk factors for SCD in Thoroughbreds by evaluating a sample with a policy of mandatory post-mortem following racing or training fatalities. Risk factors were compared between case horses with SCD (n = 57) and control horses with other fatal injury (OFI, n = 188) by univariable and multivariable logistic regression. Survival in years for horses with SCD was compared to OFI using the Kaplan−Meier method with log rank test. The following varia...
Weis R, Carstensen H, Sattler SM, Buhl R, Hesselkilde EM.During acute myocardial infarction (AMI), the ischemia and necrosis of the infarcted tissue result in local electrophysiological changes, which bring about deviations of the ST segment and T wave. In this case report, the aim was to investigate whether these changes could be detected with a 12-lead electrocardiogram (ECG) during acute occlusion of the coronary artery in a 15-year-old Standardbred mare (scheduled for euthanasia due to non-cardiac health problems). The left anterior descending (LAD) coronary artery was occluded using an angioplasty balloon catheter guided through the carotid art...
Boutet BG, Gordon SG, De Solis CN, Lepiz MA, Saunders AB, Wesselowski S.Intracardiac echocardiography (ICE) is a method of obtaining echocardiographic images with a steerable ultrasound catheter placed within the heart via a venous or arterial approach. The objectives of this study were to assess the feasibility of a 5-10 MHz, 8 French, 90 cm ICE catheter to evaluate cardiac structures and function in standing, sedated horses, and describe standard views in this species. Methods: Ten apparently healthy horses weighing 458.1-618.2 kg from a university teaching herd. Methods: Each horse had a physical examination, transthoracic echocardiography, and ICE performe...
Siwinska N, Janus I, Zak-Bochenek A, Noszczyk-Nowak A.It has been well established that obesity in horses can have a negative impact on their health, including endocrine disturbances. In humans, it is well known that obesity leads to structural and functional changes of the cardiovascular system. The aim of the study was to assess the impact of obesity on the histological structure of the myocardial tissue, as well as great and peripheral arteries in horses. The heart, arteries (aorta, pulmonary artery and palmar arteries) specimens from 7 horses with normal BCS (4-5/9) and 12 extremely obese (BCS 9/9) draft slaughter horses were obtained for his...
Huang YH, Lyle JV, Ab Razak AS, Nandi M, Marr CM, Huang CL, Aston PJ, Jeevaratnam K.Atrial fibrillation (AF) is a common cardiac arrhythmia in both human and equine populations. It is associated with adverse outcomes in humans and decreased athletic performance in both populations. Paroxysmal atrial fibrillation (PAF) presents with intermittent, self-terminating AF episodes, and is difficult to diagnose once sinus rhythm resumes. Unassigned: We aimed to detect PAF subjects from normal sinus rhythm equine electrocardiograms (ECGs) using the Symmetric Projection Attractor Reconstruction (SPAR) method to encapsulate the waveform morphology and variability as the basis of a machi...
Xue C, Cavanaugh SM.Reports of ante-mortem diagnosis of cardiovascular diseases in donkeys (Equus asinus) are rare. This case report describes the echocardiographic findings of suspected mitral valve dysplasia in a 3-year-old Nevisian donkey jenny presented for evaluation of a grade III/VI left-sided systolic murmur. Pertinent findings on transthoracic echocardiography included double mitral regurgitant jets and a bridge of tissue between the septal and mural mitral leaflets. Based upon the mild degree of cardiac remodeling and absence of clinical signs, therapeutic intervention was deemed unnecessary, and the je...
Deacon LJ, Navas de Solis C, Richardson DW, Polkes A, Reef VB.• An ACF developed in a hospitalized horse following orthopedic surgery. • Spontaneous closure of the ACF occurred 6 weeks after initial diagnosis. • Echocardiography is the primary imaging modality to confirm the presence of ACF in equids. [Figure: see text]
Hövener J, Pokar J, Merle R, Gehlen H.Heart murmurs are detected frequently when auscultating horses and certain murmurs can usually be linked to specific valvular regurgitations. Limited information exists about the accuracy of these broad rules in warmblood horses and the influence of grade of the regurgitation and dimensional changes on murmur intensity. This study aims to clarify the accuracy of cardiac auscultation in warmblood horses and the influence of the grade of regurgitation and dimensional changes on the loudness of the murmur. In this retrospective study, 822 warmblood horses presented for cardiac examination in a la...
Nath LC, Forbes G, Elliott AD, Tomren V, Ryan A, Franklin SH.AliveCor is a smartphone electrocardiography device (iECG) providing automated heart rate (HR) and rhythm determination. Atrial fibrillation (AF) in horses often is paroxysmal and rapid ECG acquisition is needed for diagnostic confirmation. iECGs were collected post-race from 15 horses with AF and 64 horses in sinus rhythm (SR). Results of manual assessment were compared to 3 commercial algorithms for HR and rhythm. Agreement between manually derived HR (HRM ) and HR derived by the AliveECG Vet (HRVET ) and Kardia version-1 (KV1 HR) and Kardia advanced (KADV HR) algorithms was quantified by th...
Premont A, Balthes S, Marr CM, Jeevaratnam K.Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis ...
D' Fonseca NMM, Beukers M, Wijnberg ID, Navas de Solis C, de Ruijter-Villani M, van Doorn DA, Stout TAE, Roelfsema E.Changes in cardiovascular parameters, including blood pressure (BP) and cardiac anatomical dimensions, are an inconsistent feature of the equine metabolic syndrome. The order in which these changes arise is unknown. Objective: Determine the order in which EMS-associated changes in cardiovascular parameters arise. Methods: Twenty Shetland pony mares. Methods: High-energy (HE) diet mares were fed 200% of net energy requirements for 1 (n = 3) or 2 (n = 7) consecutive diet-years, with 17 weeks of hay-only between years. Noninvasive BP measurements and echocardiograms were performed during bo...
Kritchevsky J, Olave C, Tinkler S, Tropf M, Ivester K, Forsythe L, Couetil L.The use of thyroid supplement is pervasive in athletic horses although its effects on measures of performance are not known. Objective: One purpose of this study was to determine whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was greater than 4 mmol/L (VLa4 ) and heart rate was over 150 (V150 ) and 200 (V200 ) beats per minute respectively. Additionally, a survey of post-race blood samples was also conducted to determine whether high thyroxine concentrations were common in racehorses. Methods: A randomised, crossover, trial was performed in six h...
Frippiat T, van Beckhoven C, Moyse E, Art T.Heart rate is evaluated in exercising horses to monitor the level of fitness to exercise, and it is usually acquired using heart rate monitors (HRM) or telemetric electrocardiograms (ECG). While HRM are commonly available and easy-to-use for horse's owners, ECG is a more expensive equipment requiring user's experience. Interest for heart rate variability (HRV) in horses is increasing for both research and clinical purposes. HRV is usually calculated from interbeat intervals (IBI) obtained by ECG. The aim of this study was to determine the accuracy of an HRM to detect IBI for the calculation of...
Saljic A, Friederike Fenner M, Winters J, Flethøj M, Eggert Eggertsen C, Carstensen H, Dalgas Nissen S, Melis Hesselkilde E, van Hunnik A....Fibroblasts maintain the extracellular matrix homeostasis and may couple to cardiomyocytes through gap junctions and thereby increase the susceptibility to slow conduction and cardiac arrhythmias, such as atrial fibrillation (AF). In this study, we used an equine model of persistent AF to characterize structural changes and the role of fibroblasts in the development of an arrhythmogenic substrate for AF. Methods: Eleven horses were subjected to atrial tachypacing until self-sustained AF developed and were kept in AF for six weeks. Horses in sinus rhythm (SR) served as control. In terminal open...
Eberhardt C, Schwarzwald CC.In horses, persistent atrial dysfunction is a prognostic indicator of recurrence of atrial fibrillation (AF). The objective of this study was to quantify left atrial (LA) contractile function in Warmblood horses after successful cardioversion of AF to sinus rhythm, using standard two-dimensional echocardiography (2DE) and two-dimensional speckle tracking (2DST) analyses, and to provide proof-of-concept for use of 2DST to detect LA contractile dysfunction in horses. Methods: Nineteen Warmblood horses with AF and successful transvenous electrical cardioversion (TVEC) or medical cardioversion usi...
De Lange L, Vera L, Decloedt A, Van Steenkiste G, Vernemmen I, van Loon G.Ventricular septal defects (VSDs) are the most common congenital cardiac defect in horses. Objective: To identify prevalence, age, breed, and sex distribution of VSD and to describe associated clinical and ultrasonographic findings. Methods: Hospital-based population of 21 136 horses presented to the equine internal medicine department. Methods: Medical records over a 12-year period were reviewed for VSD confirmed by ultrasonography. Age, breed, sex, sport discipline, murmur, clinical signs, outcome, VSD type, VSD size, shunt velocity, cardiac dimensions, concomitant cardiac anomalies, and v...
Vitale V, Laurberg M, van Galen G.Aortic valve malformation is a common congenital abnormality reported in human medicine. The malformation is characterised by an increased or decreased number of cusps. Anatomical variations of the aortic valve that have been documented in humans include unicuspid, bicuspid, quadricuspid and quinticuspid valves. Two reports described a quadricuspid aortic valve in horses associated with either a ventricular septal defect (VSD) or tetralogy of Fallot. In this case report we describe the clinical and echocardiographic findings of a horse with a quadricuspid aortic valve as single congenital abno...
De Silva M, Tagliavia C, Galiazzo G, Gifuni G, Caiazza M, Chiocchetti R, Grandis A.The morphometric studies of the atrioventricular valves are still limited in the horse. Objective: To investigate the anatomy of the atrioventricular valves in the horse, focusing on the morphometric features of the valvular leaflets and the tendinous cords. We hypothesised that accessory leaflets occur commonly and exist as independent structures in the atrioventricular valves of the horse. Methods: Descriptive anatomical study. Methods: Twenty normal hearts from slaughtered half-bred horses were used. The cardiac weight and circumference were recorded. The atrioventricular valves were expose...
Sedlinská M, Kabeš R, Novák M, Kološ F, Melková P.A five-month-old African jenny was presented with a history of exercise intolerance and syncopal episodes. Severe bradycardic arrhythmia due to a high-grade second-degree atrioventricular (AV) block with progression to complete AV block was diagnosed. The jenny underwent a transvenous single-chamber pacemaker implantation. The implantation procedure was performed in a lateral recumbency and the ventricular lead was inserted through the jugular vein. Positioning of the lead was guided by echocardiography. The pacemaker was programmed to VVI mode with a minimal ventricular rate of 40 pulses per ...
Szabó C, Vizesi Z, Vincze A.Heart rate is one of the gold standards used to assess the workload level and fitness of horses. However, when slight differences need to be detected, it is not sensitive enough. Therefore, the aim of this study was to test the effect of competition level and phase of exercise on the heart rate and heart rate variability parameters in show jumpers. Fourteen horses were examined competing on three different levels: 100 cm (n = 4), 120 cm (n = 6), and 130 cm (n = 4). The length of work (min); average and maximum heart rate; average, maximum and minimum RR intervals (ms); SD1 and SD2 (ms); RMSSD ...
Nath LC, Elliott AD, Weir J, Curl P, Rosanowski SM, Franklin S.Atrial fibrillation (AF) impacts performance and horse and jockey safety. Understanding the outcomes of AF identified postrace will better inform regulatory policy. Objective: To investigate the outcomes after episodes of AF identified postrace and determine whether affected horses are at increased risk of additional episodes compared to the general racing population. Methods: Total of 4684 Thoroughbred racehorses. Methods: Race records for Thoroughbred horses racing in Hong Kong from 2007 to 2017 were reviewed. Horses that performed below expectation were examined by cardiac auscultation and ...
Gómez-Torres FA, Estupiñán HY, Ruíz-Saurí A.The principal function of the ventricular conduction system is rapid electrical activation of the ventricles. The aim of this study is to conduct a morphometric study to pinpoint the morphological parameters that define cardiac conduction cells, allowing us to distinguish them from other cells. Five male horse hearts and five male dog hearts were used in the study. The hearts were fixed in a 5% formaldehyde solution. Histological sections of 5 μm thickness were acquired and stained with hematoxylin-eosin and Masson's trichrome and cardiac conduction cells and their junctions were identified ...
Worsman FCF, Miller ZJ, Shaw DJ, Blissitt KJ, Keen JA.Left atrial size predicts cardiac morbidity and mortality in humans and dogs. Real-time three-dimensional echocardiography (3DE) may be reliable for assessing left atrial volume (LAV) in horses. Objective: To determine intra- and interobserver variability estimates of 3DE-LAV and compare it to that of 2DE-LAV estimates. Methods: Method comparison. Methods: 3DE datasets were obtained from 40 horses, then graded for quality, creating a final study population of 22 horses. The 3DE and 2DE maximum LAV (LAV ) and minimum LAV (LAV ) were measured, and left atrial emptying volume (LA EV) and left atr...
Vernemmen I, Vera L, Van Steenkiste G, Deserranno B, Muylle S, Decloedt A, van Loon G.Arrhythmias are common in horses, but catheter-based minimally invasive electrophysiological studies and therapeutic interventions have been poorly explored in equine medicine, partly due to the lack of detailed anatomical knowledge of the equine heart. Objective: To describe the dimensions and anatomical features of some electrophysiologically important landmarks of the right atrium in detail and assess their correlation with bodyweight and aortic diameter. Methods: Ex vivo cadaveric study. Methods: Twenty-one hearts of Warmblood horses, subjected to euthanasia for noncardiovascular reasons, ...
Dirienzo LN, Dirienzo LT, Baceski DA.The study was designed to document the heart rate response to therapeutic riding in children with cerebral palsy having mild-to-severe disability. Methods: Participants consisted of eight youth riders with cerebral palsy, divided into two groups: ambulatory and wheelchair dependent. The riders received continuous digital heart rate monitoring during 10 weekly 20-minute therapeutic horseback riding sessions. Results: The averaged resting, median, and peak heart rate values, as well as the peak percentage heart rate reserve values, were significantly higher in the wheelchair-dependent group. Con...
Gunn HM.The weight of the heart as determined by dissection techniques was compared with liveweight and total muscle weight in different types of horses and dogs as adults and during growth. With increasing body size both within and between species, heart weight forms a lesser proportion of liveweight and of total muscle weight. Heart weight forms a greater proportion of liveweight in Thoroughbreds and Greyhounds (breeds noted for high speed running) than in other less fleet members of their species and Greyhounds have greater heart weights relative to total muscle weight than other dogs.
Slack J, Durandot MM, Belcher CN, Collins N, Palmer L, Ousey J, Birks EK, Marr CM.The repeatability of various echocardiographic measurements is unknown. Objective: To determine the intraoperator, intraobserver and interoperator variability of echocardiographic measures in healthy foals. Methods: Echocardiographic examinations were carried out on 6 healthy foals by 3 experienced echocardiographers. Intraoperator variability was determined by having a single echocardiographer obtain and measure images from 6 foals scanned on 3 consecutive days. Interoperator and intraobserver variability were determined by having 3 echocardiographers each obtain images from an additional 6 s...
Sleeper MM, Kearns CF, McKeever KH.Chronic administration of pharmacological levels of beta2-agonists have been shown to have toxic effects on the heart; however, no data exist on cardiac function after chronic clenbuterol administration. The purpose of this study was to examine the effect of therapeutic levels of clenbuterol on cardiac performance. Methods: Twenty unfit Standardbred mares were divided into four experimental groups: clenbuterol (2.4 microg.kg(-1) twice daily 5 d.wk(-1)) plus exercise (20 min at 50% .VO(2max)) (CLENEX; N = 6), clenbuterol (CLEN; N = 6), exercise (EX; N = 4), and control (CON; N = 4). M-mode and ...
Ibrahim HMM, Abouelnasr KS, Hamed MA, Eltayesh RA, El-Khodery SA.The aim of the present study was to assess and compare the changes of the echocardiographic dimensions and cardiac function indices after epidural injection of xylazine or dexmedetomidine in clinically healthy donkeys. In an experimental prospective randomized cross-over study, 10 healthy adult donkeys were injected with saline solution, xylazine (0.20 mg kg), and dexmedetomidine (0.005 mg kg) into the epidural space between the second and third coccygeal vertebrae. Echocardiographic dimensions as well as cardiac function indices were assessed using a 2-3.9 MHz sector transducer, at the l...
Menzies-Gow NJ.Eight normal thoroughbred horses were examined by echocardiography before and 10 minutes after they had been sedated by the intravenous administration of 0.03 mg/kg acepromazine. There were significant (P<0.025) increases in the diameters of the pulmonary artery and the aorta, measured at end-systole, and in the thickness of the interventricular septum, measured at end-systole and end-diastole. In addition, there was a significant (P<0.001) decrease in the diameter of the left atrium measured at end-diastole. The remaining cardiac dimensions, all the indices of cardiac function, and the ...
Reef VB.Ventricular septal defects (VSDs) were diagnosed in 27 horses; in 26 affected horses systolic murmurs were detected over both sides of the chest. Holodiastolic decrescendo murmurs were also detected in 5 horses. Standardbreds and Arabian horses were over-represented, while Thoroughbred horses were under-represented, when compared to the hospital population (P < 0.0001). Five horses had previously raced successfully, one 2-year-old was training successfully and close to racing, and 4 horses had competed successfully in other types of competition. Eleven horses had a history of exercise intolera...
Blissitt KJ, Bonagura JD.Reference values were established for selected Doppler derived variables from a group of 40 normal Thoroughbred and Thoroughbred cross horses. Standard two-dimensional (2-D) images used for guiding the Doppler sampling site allowed accurate alignment with flow. Tricuspid inflow velocities during rapid filling (E) and atrial contraction (A) were significantly higher when recorded from a right parasternal angled view than from a right parasternal long-axis view. In 8 horses the tricuspid inflow peak A velocity was higher than the peak E velocity. The peak acceleration of blood flow was higher (P...
Buhl R, Ersbøll AK, Eriksen L, Koch J.The purpose of this study was to assess the intraobserver variation of various echocardiographic measures in standardbred trotters. Serial echocardiographic examinations were carried out on eight standardbred mares by one ultrasonographer for 5 separate days. During each examination, five nonconsecutive cardiac cycles (frames) were recorded and an average obtained for each individual measure. Various echocardiographic measures were obtained by use of two-dimensional (2-D), M-mode, color flow Doppler and pulsed wave Doppler echocardiography. The total variation in the echocardiographic measurem...
Parks CM, Manohar M.Transmural distribution of myocardial blood flow and coronary vasodilator reserve (15-microns-diam radionuclide-labeled microspheres) was studied in 11 adult, healthy ponies at rest and during moderate and severe exercise performed on a treadmill (heart rate 56 +/- 4, 154 +/- 3, and 225 +/- 7 beats . min-1, respectively.). Exercise resulted in a marked increase in cardiac output, mean aortic pressure, right ventricular (RV) systolic and end-diastolic pressure, left ventricular (LV) end-diastolic pressure, and the maximum rate of rise of LV pressure LV (dP/dtmax). Accompanying these changes was...
Freitas MS, Pereira AHB, Pereira GO, Menezes IS, Lucena AR, Almeida CRF, Pereira EG, Santos LA, Tozin LRS, Alves FM, Macedo AL, Silva DB, Ubiali DG.Poisoning by avocado (Persea americana) has been confirmed in sheep, goats, dogs, rabbits and ostriches. The clinical signs and lesions are attributed to the acetogenin, persin. Little is known regarding the epidemiology, clinical signs, lesions and therapy caused by acetogenin-induced heart damage. During the two-year study, we investigated a horse farm with six horses that often fed themselves with P. americana leaves or mature fruit pulp and skin on the ground. Two horses died, and one underwent necropsy, histopathology, and immunohistochemistry using the anti-cardiac troponin C (cTnC). Gro...
Buschmann E, Van Steenkiste G, Boussy T, Vernemmen I, Schauvliege S, Decloedt A, van Loon G.We describe the diagnosis and treatment of an atrioventricular accessory pathway (AP) in a horse using 3-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA). During routine evaluation of the horse, intermittent ventricular pre-excitation was identified on the ECG, characterized by a short PQ interval and abnormal QRS morphology. A right cranial location of the AP was suspected from the 12-lead ECG and vectorcardiography. After precise localization of the AP using 3D EAM, ablation was performed and AP conduction was eliminated. Immediately after recovery ...
Clift SJ, Penrith ML.Tissues from 196 experimental and confirmed natural cases of African horse sickness (all 9 serotypes) were examined with a standardized and validated immunohistochemical assay for detection of the causative virus. The study confirmed that heart and lung are the main target tissues for African horse sickness virus (across all serotypes), followed closely by spleen. It also indicated that microvascular endothelial cells and monocyte-macrophages are the main target cells for virus replication. The importance of monocytes as target cells was emphasized, with relatively few tissue macrophages conta...
Bindi F, Vezzosi T, Sala G, Freccero F, Marmorini P, Bonelli F, Sgorbini M.Smartphone-based technology for ECG recording has recently spread as a complementary tool for electrocardiographic screening and monitoring in adult horses and in other animal species. The present study aimed to assess the feasibility and accuracy of a smartphone-based ECG in healthy foals. This was a prospective observational study (authorization n. 45,865/2016) including 22 foals aged less than 21 days. A reference standard base-apex ECG (rECG) was acquired, and a smartphone ECG (sECG) was recorded immediately after by using a smartphone-based single lead electrocardiograph. All ECG tracings...
Underwood C, Norton JL, Nolen-Walston RD, Dallap-Schaer BL, Boston R, Slack J.Hypohydration causes transient echocardiographic changes in pigs, dogs, humans, and cats. These changes mask the diagnosis of some cardiac diseases (valvular regurgitation, dilated cardiomyopathy) and promote the diagnosis of others (hypertropic cardiomyopathy and infiltrative disease), thus inhibiting accurate echocardiographic evaluation. Objective: To describe the echocardiographic changes associated with hypohydration in normal horses. Methods: Ten adult horses without detectable cardiac disease. Methods: Experimental study. Echocardiographic examinations were performed on horses in the eu...
Holmes JR, Alps BJ.The paper describes observations on the distributions of the P, QRS and T cardiac vectors in the horizontal plane in 377 apparently healthy horses. The possible usefulness of vectorcardiography in the clinical evaluation of cardiac function is briefly discussed.
Van Steenkiste G, L V, Decloedt A, Schauvliege S, Boussy T, van Loon G.Understanding the depolarisation pattern of the equine heart under normal physiologic conditions, and its relationship to the surface electrocardiogram (ECG), is of uppermost importance before any further research can be done about the pathophysiology of complex arrhythmias. In the present study, a 3D electro-anatomical mapping system was used to evaluate the qualitative and quantitative depolarisation patterns and correlation to the surface ECG of both the atrial and ventricular endocardium in seven healthy horses in sinus rhythm under general anaesthesia. Bipolar activation maps of the endoc...
Conley KE, Jones C.We test the hypothesis that myoglobin is important for O2 supply near the oxidative capacity of muscle. This hypothesis is evaluated with a simple model that incorporates the properties of heart and skeletal muscle tissue taken from steers and horses exercising at their maximum O2 consumption rate. These tissue samples allowed us to set the bounds on oxidative demand and O2 flux from red blood cells to the core of the muscle fiber, to estimate the blood and tissue capacities for O2 diffusion, and to define the capillary blood PO2 driving this O2 flux. A model combining blood convection with ti...
Vernemmen I, De Clercq D, Decloedt A, Vera L, Van Steenkiste G, van Loon G.The number of atrial premature depolarisations (APDs) is a known risk factor for atrial fibrillation (AF) recurrence in humans. Objective: To evaluate if the number of APDs over a 24-h period 5 days post cardioversion predicts AF recurrence within 1 year in horses, taking the multifactorial nature of AF into account. Methods: Retrospective case series. Methods: Eighty horses met these inclusion criteria: first AF episode, no AF recurrence within 5 days post cardioversion, cardioversion by transvenous electrical cardioversion (TVEC), 24-h ECG recording and echocardiographic examination 5 da...
Decloedt A, Verheyen T, Sys S, De Clercq D, van Loon G.Tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2DST) can quantify left ventricular (LV) function in horses. Objective: To evaluate LV function by TDI and 2DST in horses with myocardial dysfunction after accidental ionophore intoxication. Methods: Sixty-seven horses exposed to lasalocid in feed. Methods: Prospective study. Horses were included in the study if a full cardiac examination was performed, consisting of determination of cardiac troponin I (cTnI), electrocardiography, and echocardiography. By TDI, radial systolic velocity and strain were measured. By 2DST, circumfere...
Broux B, De Clercq D, Vera L, Ven S, Deprez P, Decloedt A, van Loon G.Heart rate variability (HRV) parameters, and especially RMSSD (root mean squared successive differences in RR interval), could distinguish atrial fibrillation (AF) from sinus rhythm(SR) in horses, as was demonstrated in a previous study. If heart rate monitors (HRM) automatically calculating RMSSD could also distinguish AF from SR, they would be useful for the monitoring of AF recurrence. The objective of the study was to assess whether RMSSD values obtained from a HRM can differentiate AF from SR in horses. Furthermore, the impact of artifact correction algorithms, integrated in the analyses ...
Pasing S, von Lewinski M, Wulf M, Erber R, Aurich C.The aim of this study was to evaluate the stress response of stallions (n = 16) aged 3-13 years with previous sexual experience to semen collection by determination of heart rate, heart rate variability, and cortisol in saliva. Recordings were done on two consecutive days. The time intervals from leaving the box until arrival in the collection barn and from first exposure to the teaser mare until ejaculation as well as the number of mounts until ejaculation were neither affected by collection day nor by age, sexual experience (i.e., the number of breeding seasons the stallion experienced), or ...
Karlström K, Essén-Gustavsson B, Lindholm A.Samples were taken at slaughter from heart and both locomotor and nonlocomotor muscles from animals of similar body weight but adapted to different levels of activity: three horses and three steers. All samples were analyzed biochemically to measure the activity of key metabolic enzymes. The skeletal muscles were analyzed histochemically for fibre type composition, fibre area and capillary supply. The general pattern of differences in fibre type composition and metabolic profile between muscle groups was similar in both horses and steers. The hearts of both species had high citrate synthase (C...
Stevens KB, Marr CM, Horn JN, Pfeiffer DU, Perkins JD, Bowen IM, Allan EJ, Campbell J, Elliott J.The effect of left-sided valvular regurgitation (LSVR) on the mortality of middle-aged and older horses was investigated in a prospective cohort study involving 19 yards and 1153 horses. The horses were examined to determine whether they had a cardiac murmur and its type, and their age, sex, breed type and occupation were recorded. They were followed up at intervals of two years by postal questionnaire, and after four years information on 773 horses was available. There was no significant difference in the mortality of the horses with and without LSVR, but small horses had a significantly high...
Vandecasteele T, Cornillie P, van Steenkiste G, Vandevelde K, Gielen I, Vanderperren K, van Loon G.Echocardiography is the imaging technique of choice for the equine heart. Nevertheless, knowledge about ultrasonographic identification of dorsally located structures and vessels, related to the atria, in horses is scarce. Objective: To describe the echocardiographic approach and the identification of structures and vessels in relation to the atria in healthy horses. Methods: CT images from two equine hearts, casted with self-expanding foam, were segmented and used to identify atrial-related structures and vessels. These images were compared with standard and nonstandard ultrasound images from...
Buergelt CD.The few data collections that evaluate the involvement of organ systems in horse diseases are in agreement that the locomotor, gastrointestinal and nervous systems are the sites of primary disease in the vast majority of sick horses. When compared with diseases of these organ systems, equine cardiovascular diseases occur infrequently. The most detailed and comprehensive survey of equine cardiac pathology was reported in 1972 by Else and Holmes, who summarized the gross and microscopic cardiac findings from 1500 abattoir horses. This paper reviews the pathology of the cardiovascular diseases ty...
