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.
Buhl R, Carstensen H, Hesselkilde EZ, Klein BZ, Hougaard KM, Ravn KB, Loft-Andersen AV, Fenner MF, Pipper C, Jespersen T.Atrial fibrillation (AF) is the most common arrhythmia affecting performance in horses. However, no previous studies have quantified the performance reduction in horses suffering from AF. Objective: To quantify the effect of AF on maximum velocity (Vmax ), maximum heart rate (HRmax ), heart rate recovery (T100 ), hematologic parameters and development of abnormal QRS complexes. Methods: Nine Standardbred trotters. Methods: Two-arm controlled trial. Six horses had AF induced by means of a pacemaker and 3 served as sham-operated controls. All horses were subjected to an exercise test to fatigue ...
Gehlen H, Bildheim LM.An effect of aging on cardiac morphology and function has been shown in humans. In horses, cardiac wall motion analysis using two-dimensional speckle tracking (2D-ST) has not yet been reported. Our study included 57 horses of different warmblood breeds between 3 and 30 years old. Age had a significant influence on left ventricular free wall (LVFW) systolic strain rate ( ≤ 0.05) and early diastolic relaxation ( ≤ 0.01). In the interventricular septum (IVS), systolic ( ≤ 0.01) and late diastolic ( ≤ 0.05) contraction velocities also increased with age. In our study, 2D-ST revealed import...
Freccero F, Cordella A, Dondi F, Castagnetti C, Niinistö K, Cipone M.In dogs, due to better alignment with the aortic outflow, the subcostal (SC) transducer site provides greater Doppler-derived velocities than those obtained from the left parasternal view. The feasibility of this imaging approach has never been described in equine echocardiography. Objective: The objective of this study was to evaluate the feasibility of the SC view in newborn foals and compare aortic two-dimensional and Doppler-derived velocity measurements with those of standard parasternal long-axis (LAX) views. Methods: A prospective observational study. Methods: Twenty-three newborn healt...
Rassoli A, Fatouraee N, Guidoin R.The benefit of bioprosthetic aortic valve over mechanical valve replacements is the release of thromboembolism and digression of long-term anticoagulation treatment. The function of bioprostheses and their efficiency is known to depend on the mechanical properties of the leaflet tissue. So it is necessary to select a suitable tissue for the bioprosthesis. The purpose of the present study is to clarify the viscoelastic behavior of bovine, equine, and porcine pericardium. In this study, pericardiums were compared mechanically from the viscoelastic aspect. After fixation of the tissues in glutara...
Trachsel DS, Tejada MA, Groesfjeld Christensen V, Pedersen PJ, Kanters JK, Buhl R, Calloe K, Klaerke DA.The long QT syndrome (LQTS) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. Pharmacologically induced LQTS is caused by interaction between drugs and potassium channels, especially the K 11.1 channel. Due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. However, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. Therefore, we investigate the effect of trimethoprim-sulfadiazine (TMS), trimethoprim, sulfadiazine, and detomidine...
De Clercq D, Broux B, Vera L, Decloedt A, van Loon G.In human and veterinary medicine, monophasic action potential (MAP) analysis and determination of local refractory periods by contact electrode technique gives valuable information about local cardiac electrophysiological properties. It is used to investigate dysrhythmias and the impact of drugs on the myocardium. Precise measurement of total MAP duration is difficult, therefore the MAP duration is usually determined at a repolarization level of 90% (APD90). Until now, no studies are published about the feasibility of this technique in the standing non-sedated horse. In 6 healthy Warmblood hor...
Decloedt A, Broux B, De Clercq D, Deprez P, Van Steenkiste G, Vera L, Ven S, van Loon G.Based on its pharmacokinetic profile and electrophysiological effects in healthy horses, sotalol potentially could be used as a long-term PO antiarrhythmic drug in horses. Objective: To evaluate the effect of sotalol on heart rate (HR), QT interval, atrial fibrillatory rate, and success of cardioversion in horses with naturally occurring chronic atrial fibrillation (AF). Methods: Twenty-eight horses referred for transvenous electrical cardioversion of AF were treated with 2 mg/kg sotalol PO q12h for 3 days before cardioversion, and 13 horses underwent the same protocol without sotalol administ...
Malinowski K, Yee C, Tevlin JM, Birks EK, Durando MM, Pournajafi-Nazarloo H, Cavaiola AA, McKeever KH.With the increase in the number of horses being used in Equine-Assisted Activities and Therapies (EAAT) programs and with the increasing concern for animal welfare, it is important to understand the impact of such interventions on the stress level and quality of life for the horses involved. The purpose of the present pilot study was to test the hypothesis that participation in EAAT would acutely alter physiological markers of stress and well-being, including plasma cortisol, plasma oxytocin, and heart rate variability (HRV), in horses and that symptoms of posttraumatic stress disorder (PTSD) ...
Ven S, Decloedt A, De Clercq D, Vera L, Rademakers F, van Loon G.Aortic regurgitation (AR) can have an important clinical impact and in some cases leads to left ventricular (LV) failure. Tissue Doppler imaging (TDI) is an echocardiographic technique that has been used in horses to detect LV dysfunction. Objective: To examine whether TDI detects changes in radial myocardial wall motion in horses with AR compared with control horses. Methods: Case-control study. Methods: Echocardiography was performed in 30 healthy Warmblood horses and 34 Warmblood horses with AR, subdivided in groups with mild, moderate or severe AR. TDI measurements were performed on six se...
Kokubun T, Oikawa M, Ichijo Y, Matsumoto Y, Yokokawa T, Nakazato K, Sato Y, Takase S, Shinjo H, Yokoyama H, Suzuki H, Saitoh SI, Takeishi Y.A 40-year-old man was transferred to our hospital following an isolated horse kick injury to the anterior chest wall. The case showed bi-fascicular block, severe tricuspid valve regurgitation due to ruptured chordae tendineae of the anterior leaflet, moderate mitral valve regurgitation due to prolapse of mitral anterior leaflet, and hypokinetic motion of the inferior septal wall. Both tricuspid and mitral insufficiency were completely repaired by a surgical operation. Fortunately, these injuries were not fatal in this case, but the comprehensive assessment of cardiac damage and careful observa...
Rossi TM, Kavsak PA, Maxie MG, Pearl DL, Pyle WG, Physick-Sheard PW.Human cardiac troponin I (cTnI) assays have been used in equine medicine, often without prior analytical validation for equine use. In the absence of appropriate validation, the clinical significance of assay results is uncertain and can lead to misdiagnosis. We followed the American Society for Veterinary Clinical Pathology guidelines and investigated linearity, precision, limit of quantification (LoQ), and comparative recovery for 6 commercial cTnI assays developed for use in human medicine. Clinically acceptable linearity was observed in assays A-D, whereas assay E did not detect equine cTn...
Hesselkilde EZ, Carstensen H, Haugaard MM, Carlson J, Pehrson S, Jespersen T, Buhl R, Platonov PG.Atrial fibrillatory cycle length has been considered one of the indices of atrial electrical remodelling during atrial fibrillation (AF), which can be assessed from surface ECG by computer-assisted calculation of atrial fibrillatory rate (AFR). Horses have been suggested as a bona fide model for AF studies since horses too, develop lone AF, however data on AF characteristics in horses are extremely sparse and non-invasive characterization of AF complexity using surface ECG processing has not been reported. Objective: The aim was to study characteristics of induced AF and its modification by fl...
Afonso T, Giguère S, Brown SA, Barton MH, Rapoport G, Barba M, Dembek KA, Toribio RE, Coleman AE.Despite the paucity of data available, orally administered angiotensin-converting enzyme (ACE) inhibitors are empirically used in horses with valvular regurgitation. Objective: Evaluate the echocardiographic and hormonal changes in response to oral benazepril in horses with left-sided valvular regurgitation. Methods: Prospective, randomised double-blind, placebo-controlled trial. Methods: Horses with mitral valve (MR) and/or aortic valve regurgitation (AR) received oral benazepril (n = 6) at a dosage of 1 mg/kg q 12 h or a placebo (n = 5) for 28 days. Echocardiography was performed before drug...
Kohnken R, Schober K, Godman J, Gardner A, Jenkins T, Schroeder E, Baker P, Dunbar L.A 4-week-old American Quarter Horse colt presented with a recent history of diarrhea and decreased activity level. On initial physical examination, the animal was bright and alert and major findings were limited to a loud systolic heart murmur radiating widely over both sides of the thorax. While in the hospital, the clinical condition of the foal warranted further imaging to determine the cause and extent of cardiac disease. A variety of congenital cardiac malformations were identified during echocardiographic examination and autopsy, including a double outlet right ventricle and a subpulmona...
Carstensen H, Kjær L, Haugaard MM, Flethøj M, Hesselkilde EZ, Kanters JK, Pehrson S, Buhl R, Jespersen T.Antiarrhythmic compounds against atrial fibrillation (AF) often have reduced efficacy and may display cardiac and/or noncardiac toxicity. Efficacy can be improved by combining 2 compounds with distinct mechanisms, and it may be possible to use lower doses of each compound, thereby reducing the likelihood of adverse side effects. The purpose of this study was to investigate whether the effective doses of dofetilide and ranolazine can be reduced if the drugs are combined. Dofetilide, ranolazine, and a combination of these were administered in 4 incremental dosing regimens to horses with acutely ...
Lenoir A, Trachsel DS, Younes M, Barrey E, Robert C.Analysis of the heart rate variability (HRV) gains more and more importance in the assessment of training practice and welfare in equine industry. It relies on mathematical analyses of reliably and accurately measured variations in successive inter-beat intervals, measured as RR intervals. Nowadays, the RR intervals can be obtained through two different techniques: a heart rate meter (HRM) or an electrocardiogram (ECG). The agreement and reliability of these devices has not been fully assessed, especially for recordings during exercise. The purpose of this study was to assess the agreement of ...
Decloedt A, De Clercq D, Ven S, Vera L, van Loon G.The disproportionate rise of pulmonary artery pressure compared to systemic blood pressure during exercise can lead to detrimental right ventricular remodelling in endurance athletes. Horses may act as an extreme model of these athletic cardiovascular adaptations, as they show a three fold increase in pulmonary pressures during exercise. Right ventricular function was examined in ten healthy horses using post-exercise and pharmacological stress echocardiography in a randomised cross-over design. Exercise testing was performed on a treadmill while pharmacological testing was performed using an ...
Dube S, Chionuma H, Matoq A, Alshiekh-Nasany R, Abbott L, Poiesz BJ, Dube DK.In order to better understand the training and athletic activity of horses, we must have complete understanding of the isoform diversity of various myofibrillar protein genes like tropomyosin. Tropomyosin (TPM), a coiled-coil dimeric protein, is a component of thin filament in striated muscles. In mammals, four TPM genes (TPM1, TPM2, TPM3, and TPM4) generate a multitude of TPM isoforms via alternate splicing and/or using different promoters. Unfortunately, our knowledge of TPM isoform diversity in the horse is very limited. Hence, we undertook a comprehensive exploratory study of various TPM i...
Kraus M, Physick-Sheard PW, Brito LF, Schenkel FS.The number of Standardbred racehorses admitted to the Ontario Veterinary College Teaching Hospital (Guelph, Canada) for treatment of atrial fibrillation (AF) has been on the rise since the early 1990s. A small number of sires have been contributing to a large proportion of cases, indicating there may be a genetic predisposition to the arrhythmia in this breed. Objective: The objectives of this study were to determine the heritability of AF in Standardbred horses and whether heritability of the arrhythmia differs across gaits and/or sexes. Methods: Heritability study based on retrospective revi...
Sleeper MM.Heart disease can be defined as any abnormality of the heart whether it is a cardiac dysrhythmia or structural heart disease, either congenital or acquired. Heart failure occurs when a cardiac abnormality results in the inability of the heart to pump enough blood to meet the body's needs. Heart disease can be present without leading to heart failure. Heart failure, however, is a consequence of heart disease. There are 4 main areas where the clinician can intervene to improve cardiac output with heart failure: preload, afterload, myocardial contractility, and heart rate.
Heliczer N, Mitchell K, Lorello O, Dauvillier J, Burger D, Schwarzwald CC, Navas de Solis C.A 20-year-old warmblood breeding stallion presented to a University practice for semen collection and evaluation was incidentally diagnosed with atrial fibrillation (AF). Electrocardiogram recordings during breeding revealed inappropriately rapid tachycardia and occasional ventricular premature depolarizations/aberrant ventricular conduction. Transvenous electrical cardioversion was performed. After successful cardioversion the horse displayed supraventricular ectopy and atrial contractile dysfunction and was administered sotalol hydrochloride in an attempt to decrease the risk of AF recurrenc...
Portella LP, Cadore GC, Sangioni LA, Pellegrini LF, Fighera R, Ramos F, Vogel FS.Sarcocystis spp., Neospora spp., and Toxoplasma gondii are Apicomplexa protozoa that can infect horses. This study aimed to investigate the occurrence of antibodies against Sarcocystis spp., Neospora spp., and T. gondii in horses slaughtered in southern Brazil. The presence of histological lesions, tissue cysts, and Sarcocystis spp. DNA in the hearts of these horses was also investigated. A total of 197 paired serum and heart samples were evaluated by serology and direct microscopic examination; 50 of these samples were subjected to histopathological and PCR analyses. Antibodies against at lea...
Luethy D, Slack J, Kraus MS, Gelzer AR, Habecker P, Johnson AL.Third-degree atrioventricular block (AVB) and primary inflammatory myocarditis are uncommon findings in horses. The horse of this report presented for collapse at rest and was found to have multiple cardiac arrhythmias, most notably 3rd-degree AVB. The horse was subsequently diagnosed with eosinophilic myocarditis on necropsy, a rare form of myocarditis not previously reported in horses. Despite extensive testing, an etiologic agent could not be identified, illustrating the difficulty in identifying a specific cause of myocarditis in horses.
Whelchel DD, Tennent-Brown BS, Coleman AE, Rapoport GS, Blas-Machado U, Maisenbacher HW, Credille BC, Giguère S.To describe the treatment of persistent supraventricular tachycardia (SVT) in a young horse in endurance training. Methods: A 6-year-old Arab gelding in endurance training presented for a dysrhythmia and decreased performance. SVT was diagnosed and conversion to a normal sinus rhythm was achieved following administration of a constant rate infusion of amiodarone. However, reversion to SVT occurred shortly after initiation of ridden exercise. A second attempt to convert the dysrhythmia with amiodarone failed, but normal sinus rhythm was achieved with transvenous electrical cardioversion (TVEC)....
Brinkman EL, Weed BC, Patnaik SS, Brazile BL, Centini RM, Wills RW, Olivier B, Sledge DG, Cooley J, Liao J, Rashmir-Raven AM.OBJECTIVE To compare biomechanical and histologic features of heart valves and echocardiographic findings between Quarter Horses with and without heritable equine regional dermal asthenia (HERDA). DESIGN Prospective case-control study. ANIMALS 41 Quarter Horses. PROCEDURES Ultimate tensile strength (UTS) of aortic and mitral valve leaflets was assessed by biomechanical testing in 5 horses with HERDA and 5 horses without HERDA (controls). Histologic evaluation of aortic and mitral valves was performed for 6 HERDA-affected and 3 control horses. Echocardiography was performed in 14 HERDA-affected...
Shave R, Howatson G, Dickson D, Young L.Physical activity is dependent upon the cardiovascular system adequately delivering blood to meet the metabolic and thermoregulatory demands of exercise. Animals who regularly exercise therefore require a well-adapted heart to support this delivery. The purpose of this review is to examine cardiac structure, and the potential for exercise-induced cardiac remodeling, in animals that regularly engage in strenuous activity. Specifically, we draw upon the literature that has studied the "athlete's heart" in humans, horses, and dogs, to enable the reader to compare and contrast cardiac remodeling i...
Koenig TR, Mitchell KJ, Schwarzwald CC.Assessment of left ventricular (LV) function by tissue Doppler imaging (TDI) is not well established in horses with heart disease. Objective: To describe the use of pulsed-wave (PW) TDI for the assessment of LV function, establish reference intervals, investigate effects of mitral regurgitation (MR), aortic regurgitation (AR), and primary myocardial disease (MD), and provide proof of concept for the use of PW TDI in Warmblood horses with heart disease. Methods: Thirty healthy horses, 38 horses with MR, 25 with AR, 8 with MD. Methods: Echocardiograms were retrospectively analyzed. Reference int...
da Costa CF, Samesima N, Pastore CA.Different methodologies for electrocardiographic acquisition in horses have been used since the first ECG recordings in equines were reported early in the last century. This study aimed to determine the best ECG electrodes positioning method and the most reliable calculation of mean cardiac axis (MEA) in equines. Methods: We evaluated the electrocardiographic profile of 53 clinically healthy Thoroughbreds, 38 males and 15 females, with ages ranging 2-7 years old, all reared at the São Paulo Jockey Club, in Brazil. Two ECG tracings were recorded from each animal, one using the Dubois lead posi...
Vitanova K, Cleuziou J, Pabst von Ohain J, Burri M, Eicken A, Lange R.The development of recoarctation after the Norwood I procedure is a known complication in patients with hypoplastic left heart syndrome (HLHS). Methods: We reviewed data on 194 consecutive patients with HLHS who underwent the Norwood I procedure between 2000 and 2015. All patients who survived until the second stage of the procedure were included. Recoarctation was defined by the need for intervention, either catheter based or surgical. The aim of our study was to determine if the patch material used for the initial arch reconstruction had an influence on the development of recoarctation. Resu...
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...
Scansen BA.Congenital heart disease (CHD) represents a small proportion of horses undergoing clinical evaluation; however, both simple and complex defects occur during cardiac development leading to many unique malformations. This article reviews cardiac development and the fetal circulation, describes the morphologic method and the sequential segmental approach to CHD analysis, presents a summary of CHD in horses, and offers an overview of lesions that should be considered during evaluation of horses suspected to have CHD. For many forms of equine CHD, therapies are limited because cardiac interventions...
Bonagura JD, Blissitt KJ.Echocardiography encompasses a number of specific imaging techniques. The two-dimensional (2-D) echocardiogram is used to identify lesions of the heart and great vessels, assess myocardial function and provide a template for guiding contrast echocardiography, colour-coded Doppler echocardiography and spectral Doppler studies. M-mode echocardiography is used to measure cardiac size and ventricular function and can be combined with contrast or colour-coded Doppler studies for accurate timing of flow events. Pulsed wave and continuous wave Doppler echocardiography display the direction and veloci...
Rassoli A, Fatouraee N, Guidoin R.The benefit of bioprosthetic aortic valve over mechanical valve replacements is the release of thromboembolism and digression of long-term anticoagulation treatment. The function of bioprostheses and their efficiency is known to depend on the mechanical properties of the leaflet tissue. So it is necessary to select a suitable tissue for the bioprosthesis. The purpose of the present study is to clarify the viscoelastic behavior of bovine, equine, and porcine pericardium. In this study, pericardiums were compared mechanically from the viscoelastic aspect. After fixation of the tissues in glutara...
Bayly WM, Reed SM, Leathers CW, Brown CM, Traub JL, Paradis MR, Palmer GH.Five Arabian or half-Arabian foals with suspected multiple cardiac anomalies were examined. Various combinations of clinical examination, electrocardiography, angiocardiography, cardiac catheterization, blood gas analysis, radiography, and echocardiography resulted in clinical data that allowed accurate antemortem diagnoses to be made. In 4 cases, the clinical diagnosis was substantiated by postmortem findings. The confirmed diagnoses were: pseudotruncus arteriosus, a combination of patent ductus arteriosus, pulmonic stenosis, and tricuspid stenosis, pentalogy of Fallot, and tricuspid atresia....
Hinchcliff KW, Muir WW.Furosemide, a diuretic, is frequently administered to horses for the prophylaxis of exercise-induced pulmonary hemorrhage and the treatment of a number of clinical conditions, including acute renal failure and congestive heart failure. Furosemide increases the rate of urinary sodium, chloride, and hydrogen ion excretion. Plasma potassium concentration decreases after furosemide administration but urinary potassium excretion in horses is minimally affected. Renal blood flow increases after furosemide administration. Systemically, furosemide increases venous compliance and decreases right atrial...
Lorello O, Ramseyer A, Burger D, Gerber V, Navas de Solis C.The objectives of this study were to describe the changes in clinical cardiovascular examination variables over a competition season in groups of competitive eventing and endurance horses and to compare these findings to non-competitive controls of the same breeds. Methods: This study included two eventing horses, 11 endurance horses, and 13 eventing and seven endurance control breed-matched horses. Methods: Cardiovascular examinations were performed before starting the competition season, in the middle and at the peak/end of the competition season. Examinations included auscultation of the he...
Schipke J, Mayhew TM, Mühlfeld C.Body mass (BM) of terrestrial mammalian species ranges from a few grams in the case of the Etruscan shrew to a few tonnes for an elephant. The mass-specific metabolic rate, as well as heart rate, decrease with increasing BM, whereas heart mass is proportional to BM. In the present study, we investigated the scaling behaviour of several compartments of the left ventricular myocardium, notably its innervation, capillaries and cardiomyocytes. Myocardial samples were taken from 10 mammalian species with BM between approximately 2 g and 900 kg. Samples were analysed by design-based stereology and e...
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 ...
Farag AMM, Ibrahim HMM.Donkey (Equus asinus), the cheapest form of agricultural power in Egypt, is used principally as draught or pack animals and may also be ridden, or used for threshing, raising water, milling, and other work. The aim of the present study was to provide B-mode and M-mode echocardiographic reference ranges from a sample of population of donkeys (E. asinus) based on the probability theory and statistics. In the present study, B-mode and 2-dimensional guided M-mode echocardiography were performed on 44 clinically healthy donkeys (E. asinus) (22 males and 22 females), without any neither clinical nor...
Ennezat PV, Darchis J, Lamblin N, Tricot O, Elkohen M, Aumégeat V, Equine O, Dujardin X, Saadouni H, Le Tourneau T, de Groote P, Bauters C.Although mitral regurgitation (MR) has been associated with an increased risk of death and heart failure after myocardial infarction (MI), the relationship between post-MI MR and left ventricular (LV) remodeling has not been entirely clarified. In addition, the optimal timing for assessing MR after MI remains unknown. Methods: Post-MI MR was assessed by Doppler echocardiography at hospital discharge (baseline) and after 3 months in 261 patients with an inaugural anterior MI. We studied LV remodeling during a 1-year period and clinical follow-up after 3 years, according to MR severity at baseli...
Decloedt A, De Clercq D, Ven S, Vera L, van Loon G.The disproportionate rise of pulmonary artery pressure compared to systemic blood pressure during exercise can lead to detrimental right ventricular remodelling in endurance athletes. Horses may act as an extreme model of these athletic cardiovascular adaptations, as they show a three fold increase in pulmonary pressures during exercise. Right ventricular function was examined in ten healthy horses using post-exercise and pharmacological stress echocardiography in a randomised cross-over design. Exercise testing was performed on a treadmill while pharmacological testing was performed using an ...
Elbrønd VS, Thomsen MB, Isaksen JL, Lunde ED, Vincenti S, Wang T, Tranum-Jensen J, Calloe K.The Purkinje fibers convey the electrical impulses at much higher speed than the working myocardial cells. Thus, the distribution of the Purkinje network is of paramount importance for the timing and coordination of ventricular activation. The Purkinje fibers are found in the subendocardium of all species of mammals, but some mammals also possess an intramural Purkinje fiber network that provides for relatively instantaneous, burst-like activation of the entire ventricular wall, and gives rise to an rS configuration in lead II of the ECG. To relate the topography of the horse heart and the dis...
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 ...
Zuber N, Zuber M, Schwarzwald CC.Assessment of cardiac electromechanical function in horses requires training, experience and specialised equipment and does not allow continuous monitoring over time. Objective: The objective of this study was to establish the use of an acoustic ECG monitor (Audicor ) in healthy horses. It provides noninvasive, examiner-independent, continuous analyses combining ECG and phonocardiography to calculate indices of cardiac mechanical activity and haemodynamics. Device usability was investigated, reference intervals calculated and reproducibility of analyses assessed. Methods: Prospective descripti...
Marr CM.Degenerative myxomatous disease is common and is associated with aging. Poor prognostic indicators for equine aortic regurgitation specifically include ventricular ectopy, increased pulse pressure, and hyperkinetic pulses. Valvular prolapse is a functional abnormality diagnosed echocardiographically, about which knowledge is limited. A better understanding of its role in valvular regurgitation is needed. Infective endocarditis presents with fever and other systemic signs accompanying valvular regurgitation. The prognosis is poor, warranting aggressive therapy. Other forms of valvular disease o...
Brown CC, Meyer RF, Grubman MJ.In a retrospective study, a negative-sense digoxigenin-labeled RNA probe, corresponding to the gene encoding nonstructural protein-1 of African horse sickness virus (AHSV) serotype 4, was applied to formalin-fixed, paraffin-embedded tissue taken from horses in the terminal stages of infection with AHSV. Fifteen infected ponies and one noninfected control were studied. Ponies exhibited a range of clinical signs and lesions. Thirteen ponies were infected with serotype 4, one with serotype 1, and one with serotype 2. Ponies were monitored clinically and euthanatized when severely clinically ill. ...
Bakos Z, Vörös K, Järvinen T, Reiczigel J.The aim of the study was to establish normal echocardiographic values of healthy Standardbred trotters not published previously. Twenty-three clinically normal horses weighing between 350 and 490 kg were examined in the same manner: first a thorough physical and then detailed echocardiographic examination were performed. Standardised two-dimensional (2D) and guided M-mode echocardiographic imaging techniques were used to measure interventricular septal thickness (IVS), left ventricular internal diameter (LVID), left ventricular wall thickness (LVW), left atrial internal diameter (LAID) in end-...
Manohar M, Bisgard GE, Bullard V, Will JA, Anderson D, Rankin JH.Hemodynamics, myocardial function, and regional myocardial blood flow (MBF) were measured in 6 closed-chest ponies anesthetized with ketamine hydrochloride before (control) and after creation of acute right ventricular systolic hypertension (RVSH) during normoxia and isocapnic hypoxia. The right ventricular (RV) systolic pressure during each RVSH approached 90 mmHg. There were significant alterations in the pattern of total ventricular MBG distribution in favor of the RV. Because RV myocardium received proportionate increments to its endocardium as well as epicardium, it is concluded that auto...
Poochipakorn C, Wonghanchao T, Huangsaksri O, Sanigavatee K, Joongpan W, Tongsangiam P, Charoenchanikran P, Chanda M.During an African horse sickness (AHS) outbreak, horses were able to exercise daily in a net-covered arena, yet the physiological responses to exercise in a netted arena was unknown. In a cross-over study design, eight horses performed a 39-minute aerobic exercise in conventional (CA) and vector-protected arenas (VPA). Horses were slower in some gaits and covered less distance in the VPA arena (P < .01). Cortisol release, hematology, and heart rate variability (HRV) were also examined. An interaction between the riding arena and time was observed in hematocrit (P = .0013), hemoglobin (P = ...
Eichler F, Ehrle A, Machnik M, Jensen KC, Wagner S, Baudisch N, Bolk J, Pötzsch M, Thevis M, Bäumer W, Lischer C, Wiegard M.As a remedy against stress and anxiety, cannabidiol (CBD) products are of increasing interest in veterinary medicine. Limited data is available describing the actual effectiveness of CBD in horses. The aim of this study (part 2 of 2) was to analyze stress parameters via behavioral observation, heart rate monitoring and assessment of blood and saliva cortisol levels in healthy horses treated repeatedly with a CBD containing paste. Twelve horses were randomly assigned to a treatment or a control group. Two pastes were orally administered in a double-blinded study design, one paste containing CBD...
Adler DMT, Hopster K, Hopster-Iversen C, Fenner M, Buhl R, Jacobsen S.Thoracotomy is an uncommon procedure in horses but remains essential in a variety of cases of pleuropneumonia, pericarditis, thoracic trauma or diaphragmatic herniation, and for experimental thoracic and cardiac procedures. This study aimed at developing an experimental surgical procedure allowing access to the entire circumference of the heart and describing the effect of thoracotomy on pulmonary gas exchange in these horses. The study consisted of two arms, arm one (undergoing thoracotomy), was a terminal experimental study that included 11 Standardbred horses with experimentally induced (by...
Aida H, Steffey EP, Pascoe JR, Yarbrough TB, Takahashi T, Hiraga A, Hobo S, Smith BL, Steffey MA, Jones JH.To evaluate sevoflurane as an inhalation anesthetic for thoracotomy in horses. Methods: 18 horses between 2 and 15 years old. Methods: 4 horses were used to develop surgical techniques and were euthanatized at the end of the procedure. The remaining 14 horses were selected, because they had an episode of bleeding from their lungs during strenuous exercise. General anesthesia was induced with xylazine (1.0 mg/kg of body weight, IV) followed by ketamine (2.0 mg/kg, IV). Anesthesia was maintained with sevoflurane in oxygen delivered via a circle anesthetic breathing circuit. Ventilation was contr...
Yamada K, Sato F, Horiuchi N, Higuchi T, Kobayashi Y, Sasaki N, Nambo Y.Autopsy imaging (Ai), postmortem imaging before necropsy, is used in human forensic medicine. Ai was performed using computed tomography (CT) for a 1-month-old Thoroughbred foal cadaver found in a pasture. CT revealed pericardial effusion, collapse of the aorta, bleeding in the lung lobe, gas in the ventricles and liver parenchyma, and distension of the digestive tract. Rupture in the left auricle was confirmed by necropsy; however, it was not depicted on CT. Therefore, Ai and conventional necropsy are considered to complement each other. The cause of death was determined to be traumatic cardi...
Vandecasteele T, van Loon G, Vandevelde K, De Pauw B, Simoens P, Cornillie P.Information on ultrasound examination of equine pulmonary veins is scarce due to a lack of in-depth anatomical information. Each pulmonary vein drains a specific lung lobe region, after which those veins merge into a collecting antrum, before opening into the left atrium through their respective ostia. The aim of this study was, by using anatomical dissection and silicone casting of equine cardiopulmonary sets, to study the venous drainage of both lungs and the position of the ostia and to investigate whether the ostia can be identified and differentiated using ultrasound. Three out of the fou...
Cornelisse CJ, Schott HC, Olivier NB, Mullaney TP, Koller A, Wilson DV, Derksen FJ.An 18-year-old Thoroughbred gelding was evaluated because of sudden onset of ventricular tachycardia and signs of colic. Three years earlier, a diastolic decrescendo murmur, consistent with aortic regurgitation, had been detected, but the horse continued to perform well and compete successfully. Cardiac ultrasonographic examination revealed a defect in the interventricular septum below the aortic root, and serum concentrations of cardiac troponin I (cTnI) were higher than those measured in clinically normal horses. Repeated development of tachyarrhythmia during hospitalization prompted a decis...
Frye MA, Selders CG, Mama KR, Wagner AE, Bright JM.Rectilinear biphasic cardioversion was used in 2 horses with idiopathic sustained atrial fibrillation; 1 horse converted to sustained sinus rhythm. Variables that potentially affected outcome of the electrical cardioversion procedures in these horses included duration of arrhythmia, placement of cardioverter pads and paddles, serum electrolyte concentrations, and treatment with quinidine. Serum cardiac troponin I concentration, measured to determine whether the myocardium was damaged from the electrical shocks, was within the reference range in both horses after the procedure. Biphasic electri...
