Echocardiography is a diagnostic imaging technique used to assess the heart's structure and function in horses. It utilizes ultrasound waves to create detailed images of the heart, allowing veterinarians to evaluate cardiac anatomy, blood flow, and heart motion. Echocardiography is instrumental in diagnosing various cardiac conditions, such as valvular disorders, congenital heart defects, and myocardial diseases in equine patients. The procedure provides valuable information on heart size, wall thickness, and chamber dimensions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and clinical implications of echocardiography in equine cardiology.
Young LE, Blissitt KJ, Clutton RE, Molony V.To describe the haemodynamic effects of a 60 min infusion of dopamine 4 microg/kg bwt/min during halothane anaesthesia, 7 mature Thoroughbred horses were studied. The infusion began 1 h after induction of anaesthesia by romifidine (100 microg/kg) and ketamine (2.2 mg/kg bwt). Throughout the period of dopamine infusion and for 30 min after its discontinuation, the horses were ventilated by intermittent positive pressure to maintain PaCO2 between 4.6-5.4 KPa. Inspired halothane concentration was adjusted to maintain an end tidal halothane concentration of 0.9%. Haemodynamic variables were measur...
Maxson-Sage A, Parente EJ, Beech J, Lindborg S, May LL, Teleis DC.To determine the effect of exercise on arterial blood gas tensions and upper airway and cardiac function in clinically normal Quarter Horses and horses heterozygous and homozygous for hyperkalemic periodic paralysis (HYPP). ANIMALS AND PROCEDURE: 5 clinically normal Quarter Horses, and 5 heterozygous and 2 homozygous HYPP-affected horses were examined before, during, and after exercise on a high-speed treadmill. Arterial blood gas tensions, ECG, and echocardiogram were obtained prior to exercise. Upper airway endoscopy, collection of arterial blood samples, and continuous electrocardiography w...
Young LE, Scott GR.In order to assess the reliability and repeatability of transthoracic echocardiography for detecting serial changes in cardiac function in horses, day to day variability of a number of echocardiographic indices of ventricular function were studied. The variables investigated were, from 2-dimensional (2-D) and M-mode echocardiography - aortic diameter in systole (Aos), pulmonary artery diameter in systole (Pas), left ventricular internal diameter in systole (LLVIDs) and diastole (LLVIDd), and left ventricular fractional shortening (%FS) and estimated ejection fraction (EF). From pulsed Doppler ...
Marr CM, Reef VB, Brazil TJ, Thomas WP, Knottenbelt DC, Kelly DF, Baker JR, Reimer JM, Maxson AD, Crowhurst JS.This report describes the history, clinical, electrocardiographic and echocardiographic findings, treatment, outcome and post-mortem findings in seven horses with aorto-cardiac fistula. Affected horses included 5 stallions, one gelding and one mare; 2 each of the Thoroughbred, Arabian and Standardbred breeds and one Thoroughbred-cross with a mean +/- s.d. age of 12 +/- 4 years, range 6-18 years. The presenting signs were acute distress (four horses), exercise intolerance (two horses) and the lesion was detected during a routine examination in one horse. Five horses had monomorphic ventricular ...
Reef VB, Bain FT, Spencer PA.Forty-three horses with mitral regurgitation (MR) and congestive heart failure were examined, using M-mode, 2-dimensional real-time and Doppler echocardiography. There was no breed or sex predisposition when compared to the general hospital population. The mean +/- s.d. age of affected horses was 7.6 +/- 8.1 years. Horses with MR and congestive heart failure had significant increases in mean values for left ventricular chamber size, left atrial size and heart rate and significant decreases in interventricular septal and left ventricular free wall thickness. Significant increases in pulmonary a...
Worth LT, Reef VB.To determine clinical signs of pericarditis in horses and to determine whether there were any relationships among clinical signs, echocardiographic findings, treatment, and outcome. Methods: Retrospective study. Methods: 18 horses. Results: Physical examination was performed on 16 horses. Cardiovascular abnormalities included tachycardia (n = 16), pericardial friction rub (10), venous distention (7), murmur (7), muffled heart sounds (6), weak arterial pulse (6), jugular pulse (6), and edema (5). Twelve horses also had respiratory abnormalities; the most common was dull lung sounds, ventrally, ...
Maxson AD, Reef VB.A retrospective study of 10 horses with bacterial endocarditis was performed in order to describe the echocardiographic findings in horses with bacterial endocarditis, in conjunction with clinical signs and post mortem findings, and to evaluate the usefulness and the formulation of a prognosis. Echocardiographic and post mortem examinations were performed in 7 horses. Post mortem examination alone was performed in 2 horses and echocardiographic examination alone performed in one horse. No breed or sex predilection was obvious. Mean age +/- s.d. was 2.12 +/- 3.32 years. Predominant clinical sig...
Young LE, Blissitt KJ, Clutton RE, Molony V.To evaluate the hemodynamic effects of a 60-minute infusion of dopexamine in horses anesthetized with halothane. Methods: 7 adult Thoroughbreds. Methods: Measurements of left ventricular function obtained by transesophageal Doppler echocardiography and cardiac catheterization. Results: Infusion of dopexamine (4 micrograms/kg of body weight/min) significantly increased heart rate, cardiac output, maximal rates of increase and decrease of left ventricular pressure, and maximal acceleration and maximal velocity of aortic blood flow. Left ventricular ejection time significantly increased, and pre-...
Vörös K.Quantitative two-dimensional echocardiography (2DE) was introduced into equine cardiology in the early 1990s. At first, linear and area dimensions and left ventricular volume were validated by the comparison of parameters determined during in vitro 2DE and autopsy measurements. Based on these studies, tomographic planes and intracardiac reference points for in vivo measurements were established and 2DE values have been determined for healthy adult horses by various authors. These data were similar to each other and proved to be comparable with M-mode echocardiography measurements. However, dif...
Young LE, Blissitt KJ, Bartram DH, Clutton RE, Molony V, Jones RS.In order to determine if transoesophageal Doppler echocardiography could be used to estimate cardiac output in anaesthetized horses, we have compared the technique with estimations of cardiac output by thermodilution in eight healthy adult thoroughbreds. Measurements of aortic blood flow velocity were made by high pulse repetition frequency (HPRF) and continuous wave (CW) Doppler echocardiography from a 3.5-MHz transoesophageal probe. Cardiac output was increased during the study by administration of dobutamine, providing a range of cardiac output measurements by thermodilution from 15.0 to 64...
Mitten LA.Exercise intolerance, due to cardiovascular disease in horses, may be caused by cardiac arrhythmias, valvular regurgitation, congenital abnormalities, myocardial dysfunction, pericardial disease, and vascular thrombosis. The most common cardiovascular cause of exercise intolerance in horses is atrial fibrillation. Cardiovascular abnormalities such as cardiac arrhythmias or murmurs, however, are common in athletic horses and are not always associated with exercise intolerance. Use of an electrocardiography (during rest and exercise) and echocardiography may be necessary to better determine the ...
Reppas GP, Canfield PJ, Hartley WJ, Hutchins DR, Hoffmann KL.An echocardiographical and clinical pathological investigation of the rapid loss of weight by a yearling thoroughbred filly revealed an atrial septal defect, a ventricular septal defect and hyperfibrinogenaemia. A post mortem examination confirmed the cardiac abnormalities and revealed a severe thoracic aortitis. It is proposed that the idiopathic thoracic aortitis contributed to the horse's compromised cardiovascular homoeostasis.
Slater JD, Herrtage ME.Echocardiographic examinations were performed on 41 clinically normal small ponies, large ponies and horses. Using standardised two-dimensional (2-D) echocardiographic images to guide M-mode studies, the interventricular septal thickness, left ventricular internal dimension and left ventricular wall in systole and diastole, and aortic diameter in diastole were measured. Normal values for these echocardiographic dimensions were obtained across a wide range of bodyweights. Although there was a trend for echocardiographic dimensions to increase with bodyweight across the whole range of animals ex...
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...
Blissitt KJ, Bonagura JD.Colour flow Doppler echocardiography is a technique that is used with two-dimensional (2-D) echocardiography to study blood flow patterns in the heart and blood vessels. This method was used to define normal flow patterns and to evaluate valvular function in 40 clinically normal Thoroughbred and Thoroughbred cross horses. Flow patterns from 10 standardised echocardiographic images were described in relation to anatomic landmarks and timing during the cardiac cycle. Consistent intracardiac flow patterns were identified in the normal horses. High velocity flow signals or regurgitant jets were re...
Blissitt KJ, Bonagura JD.Thirty-two horses with cardiac murmurs typical of tricuspid, mitral and aortic regurgitation were studied using colour flow Doppler echocardiography. The dimensions and duration of any regurgitant signals, recorded at the cardiac valve suspected as being the site of origin of the murmur, were measured. Results were compared with flow signals described at the valves of normal horses (Blissitt and Bonagura 1995). Horses with murmurs suggestive of tricuspid (n = 8) and aortic (n = 8) regurgitation showed larger regurgitant signals at the tricuspid and aortic valves respectively, than has been rep...
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...
Patteson MW, Gibbs C, Wotton PR, Cripps PJ.Twenty-six horses were sedated with detomidine hydrochloride (Domosedan, SmithKline Beecham Animal Health, Tadworth, Surrey, UK) at a dose of 10 micrograms/kg bwt, administered i.v. Echocardiograms were recorded before and after sedation, measurements of cardiac dimensions were made and functional indices were calculated. The pre- and post sedation values were compared. No significant change was detected following sedation in the ejection time (ET), left ventricular dimension, left atrial diameter at the sinotubular junction at end-systole or end-diastole or at the sinus of Valsalva at end-dia...
Patteson MW, Gibbs C, Wotton PR, Cripps PJ.Cardiac dimensions and indices of cardiac function were measured in 29 clinically normal adult Thoroughbreds (TB) which performed minimal exercise using guided M-mode and two-dimensional (2-D) echocardiography, from a variety of image planes and measurement methods, and standardised imaging planes based on intracardiac anatomical landmarks. The different methods of measuring these variables were compared. The variables which were considered to be most valuable for quantitative echocardiography were measured in a further 9 horses. Comparable measurements of cardiac dimensions can be obtained fr...
Reef VB.Physiological flow murmurs occur frequently in horses and may be difficult to distinguish from murmurs associated with underlying cardiac disease. The significance of heart murmurs auscultated in horses is often difficult to determine if the horse is not exhibiting any clinical signs or if the signs, such as poor performance, are nonspecific. A complete echocardiographic examination (M-mode, 2-dimensional (2-D) and Doppler) provides an objective assessment of the severity of the horse's underlying cardiac disease. Valvular regurgitation and ventricular septal defects (VSDs) occur frequently an...
Marr CM, Reef VB.Colour flow Doppler echocardiographic examinations were performed on 15 horses; 10 Thoroughbreds and 5 Standardbreds; 9 mares, 5 geldings and 1 stallion; mean +/- s.d. 3.4 +/- 1.1 years. Cardiac murmurs were audible in 12 horses (80%), but these had characteristics consistent with functional murmurs in all horses. A standardised two-dimensional (2-D) and M-mode echocardiographic examination was unremarkable in all horses except that aortic valve prolapse was identified in 3 horses, tricuspid valve prolapse in 2 horses and mitral valve prolapse was present in one horse. Colour flow Doppler echo...
Travers CW, van den Berg JS.This paper describes the case histories of two Thoroughbred horses, a 2-year-old colt in training and a 7-year-old broodmare, that were presented with histories of weight loss, exercise intolerance, intermittent fever, limb oedema and anaemia. Vegetative endocarditis of the mitral and tricuspid valves was diagnosed in the colt by means of echocardiography. Pseudomonas sp. endocarditis of the mitral valve was diagnosed in the mare using echocardiography and bacterial culture. The colt had secondary congestive heart failure and was euthanased on humane grounds. Pseudomonas cepacia was isolated f...
Young LE, Blissitt KJ, Clutton RE, Molony V, Darke PG.Transoesophageal Doppler echocardiography was performed in 7 Thoroughbred horses anaesthetised with halothane. The procedure was performed on 4 occasions under standard conditions. On one occasion dobutamine hydrochloride was infused at 4 micrograms/kg/min for 20 min. Recordings of aortic blood velocity, obtained using high pulsed repetition frequency Doppler echocardiography (HPRF), were used to derive maximum acceleration (dv/dtmax), maximum velocity (Vmax), left ventricular ejection time (ET), pre-ejection period (PEP), velocity time integral (VTI) and cardiac output (CO). The coefficient o...
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...
Traub-Dargatz JL, Schlipf JW, Boon J, Ogilvie GK, Bennett DG, Wingfield WE, Hutchison JM.Ventricular tachycardia develops less frequently than supraventricular dysrhythmias and generally is more indicative of cardiac disease. The horse in this report had clinical signs of lethargy and hypophagia and was determined to have sustained ventricular tachycardia. Echocardiography was a valuable diagnostic tool and revealed an echodense area in the left ventricle that had subnormal ventricular performance. A primary heart problem of an inflammatory nature was suspected. The horse responded favorably to treatment with lidocaine, antimicrobials, and aspirin, as well as stall rest. The horse...
Marr CM.Echocardiography is an extremely versatile tool for both the equine clinician and physiologist. There are three useful forms of echocardiography, B mode, M mode and Doppler. Together they provide complementary information on cardiac disease and haemodynamic status. B mode is used to image the cardiac chambers, valves, myocardium and pericardium. M mode allows determination of motion of cardiac structures; it is superior to B mode for timing of events and it is used to make precise measurements of the heart. Doppler echocardiography can assess intracardiac blood flow and its velocity. Echocardi...
Stadler P, Kinkel N, Deegen E.In 14 horses without heart disease stroke volume determination were established by pulsed wave doppler echocardiography. Thermodilution and doppler echocardiography were used simultaneously. The doppler echocardiographic volume determinations were carried out in left and right outflow tracts. Echocardiographically Velocity Time Integral, Maximum Flow Velocity, Mean Flow Velocity and Acceleration Time were ascertained. To be able to compare heart volumes of horses with different body weight stroke volume was applied to 1 kg of body weight (= heart index). Heart Index determined with thermodilut...
Hiraga A, Hobo S, Birks EK, Takahashi T, Hada T, Smith BL, Carr EA, Pascoe JR, Jones JH.Three mature Thoroughbred horses were prepared surgically with ultrasonic sonomicrometer crystals affixed to their ventricular pericardia. Signals from crystals recorded dimensions of axes across the left ventricle. Cubic algorithms were fitted to dimensional data to generate volume estimates that matched stroke volumes simultaneously measured using the Fick principle. As horses stood at rest or exercised at various intensities (approx 7, 12, 24, 47 and 100% maximal rate of O2 consumption VO2max[), left ventricular dimensions were recorded and 20 consecutive diastolic and systolic volumes calc...
Drábková Z, Amory H, Kabeš R, Melková P, van Loon G.A partial atrioventricular septal defect, represented as a large ostium primum atrial septal defect and common (bridging) atrioventricular valve leaflets with cleft septal leaflet of the mitral valve, was diagnosed incidentally in a nine-year-old warmblood gelding used for show jumping. Initial examination findings and a three-year follow-up are documented in this report. The horse was first presented for the evaluation of chronic coughing. A left-sided, grade 4/6 holosystolic (band-shaped) murmur was identified along with a similar right-sided, grade 3/6 heart murmur. Echocardiography reveale...
Kvart C, Carlsten J, Jeffcott LB, Nilsfors L.M-mode echocardiography is a safe and practical means of using ultrasound to evaluate the dynamic movements of cardiac structures. The technique can be refined by using a simple contrast medium in the form of carbon dioxide mixed with heparinised blood to provide a strong echogenic result. This technique was employed in a series of 15 normal conscious standing horses and in three animals with specific cardiac defects. In the clinical cases it was possible to confirm the diagnosis and differentiate between a congenital septal defect and mitral regurgitation. The method was found to be safe and ...
Gehlen H, Sundermann T, Rohn K, Stadler P.This study measured plasma atrial natriuretic peptide (ANP) concentration in horses with heart valve regurgitations (HVR) with and without atrial and ventricular dilatation. Background: In humans and small animals, plasma ANP concentration is increased in heart disease and correlates with the severity of clinical signs and heart enlargement. Methods: Ten healthy horses (control) and 36 horses with HVR were evaluated by auscultation, electrocardiography, echocardiography, and determination of plasma ANP. Results: Control horses demonstrated mean plasma ANP concentration of 21+/-5.4 pg/mL. Of th...
Walders W, Gehlen H.This study evaluated a device for blood pressure measurement using high definition oscillometry (HDO) for its acceptability and practicability in the horse. Furthermore, we evaluated whether this device can determine differences in blood pressure between healthy horses and horses with heart diseases and between different measurement times. Methods: The study population consisted of 60 horses (aged 4-31 years). All horses underwent clinical examination, conventional echocardiography (including cardiac output measurement at the pulmonary artery), repeated noninvasive blood pressure measurement a...
Reimer JM, Reef VB, Sommer M.Pulmonic valve rupture was determined to be the cause of severe right-sided heart failure in a 20-year-old Thoroughbred gelding. A flail in the intermediate pulmonic valve cusp was detected by 2-dimensional echocardiography. Significant pulmonic and tricuspid valvular regurgitation were confirmed by Doppler echocardiography. Despite treatment, the horse's condition deteriorated, and euthanasia was performed. At necropsy, a tear in the pulmonary artery extending into the right valve cusp and a tear at the base of the intermediate valve cusp were identified at the junction of the right and inter...
Reef VB.Mitral valvular insufficiency associated with ruptured chordae tendineae was diagnosed in 3 foals with signs of congestive heart failure, which were believed to be secondary to the development of pulmonary hypertension associated with the valvular insufficiency. The septal leaflet of the mitral valve was affected in all 3 foals, and foal 2 also had ruptured chordae tendineae associated with the caudal mitral valve leaflet. Bacterial endocarditis and myocardial necrosis were associated with the ruptured chordae tendineae in foals 3 and 2, respectively. Idiopathic rupture was considered in foal ...
Fregin GF.The approach to pre-purchase evaluation of the equine cardiovascular system is discussed with emphasis on cardiac auscultation and on the terminology that should be used when reporting clinical findings. Innocent cardiac murmurs and arrhythmias are contrasted with those that should be considered as reliable signs of cardiovascular disease. Ultrasonography and electrocardiography are recommended to establish baseline values for future reference, to support opinions rendered by the examining veterinarians, or to provide for diagnosis and treatment.
Stadler P, Weinberger T, Deegen E.Twenty adult warm blooded horses (body weight 585 +/- 59 kg) were evaluated with pulsed doppler echocardiography. Locations for the transducer and the sample volume were determined to get typical blood flow tracings of the equine heart. Angle of doppler beam was between 37 degrees and 40 degrees in right heart atrioventricular flow tract and between 44 degrees and 47 degrees in left heart atrioventricular flow tract. Peak blood flow velocity (angle corrected) was 0.71 +/- 0.17 m/s in tricuspid valve and 0.92 +/- 0.22 in mitral valve. In right and left atrioventricular flow tracts in all sample...
Lightowler C, Piccione G, Giudice E, del Olmo GR, Cattaneo ML.Prediction of potential performance is one of the goals of exercise physiology investigations. When Selecting a horse for competition, one of the main objectives is to choose the one that predictably will reveal a competitive aptitude above the average. The horses used in this study underwent a two-dimensional echocardiography study and a conventional 3 leads electrocardiogram. The results show that heart score is not an appropriate index to evaluate the heart size in the horse. On the other hand, there are currently more suitable and accurate procedures such as echocardiography that allow per...
Holmes JR, Miller PJ.The paper describes clinical observations in three horses with ruptured mitral valve chordae. Horses with ruptured mitral valve chordae may have a history of sudden onset of acute distress with predominantly respiratory symptoms. On auscultation there will be a widespread pansystolic murmur with an extension of the area of cardiac auscultation. The third heart sound may be very pronounced and unduly prolonged, associated with high volume flow during early ventricular filling in diastole. However, these sounds are not specific for chordal rupture--they are typical of severe mitral regurgitation...
Stadler P, Kinkel N, Deegen E.In 14 horses without heart disease stroke volume determination were established by pulsed wave doppler echocardiography. Thermodilution and doppler echocardiography were used simultaneously. The doppler echocardiographic volume determinations were carried out in left and right outflow tracts. Echocardiographically Velocity Time Integral, Maximum Flow Velocity, Mean Flow Velocity and Acceleration Time were ascertained. To be able to compare heart volumes of horses with different body weight stroke volume was applied to 1 kg of body weight (= heart index). Heart Index determined with thermodilut...
Mahony C, Rantanen NW, DeMichael JA, Kincaid B.Spontaneous echocardiographic contrast is the term used by ultrasonographers to describe particulate material visible in intracardiac blood by ultrasound. The purpose of the present study was to determine the prevalence of spontaneous contrast in a farm population of Thoroughbreds and in the farm's racehorses. The results showed that spontaneous echocardiographic contrast is common in Thoroughbreds, and that the prevalence of contrast is affected by age, male gender, racing and pregnancy. The amount of right-sided cardiac contrast was quantitated by videodensitometry and was increased in horse...
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...
Vörös K, Felkai C, Szilágyi Z, Papp A.Two-dimensional echocardiographic (2DE) examination was performed on a horse with clinical signs of pericardial effusion. Thickening of the pericardium, excess amount of pericardial fluid, elevation of the cardiac apex, and right ventricular compression, characteristic of cardiac tamponade, could be seen on 2DE recordings. Fibrinous pericarditis was suspected by observation of fibrinous strands in the pericardial fluid and epicardial fibrin deposits. Echocardiographically guided pericardiocentesis was performed, and 4 L of fluid was removed from the pericardial sac. Streptococcus zooepidemicus...
Kis J, Rózsa L, Husvéth F, Mezőszentgyörgyi D, Kovács S, Bakos Z, Zsolnai A, Anton I.The g.66493737C/T polymorphism of the myostatin gene (MSTN) majorly influences muscle fiber composition and best race distance of Thoroughbreds. Thus, a better understanding of this process may lead to superior genetic exploitation for maximizing Thoroughbred athletic potential. Our objective is to investigate whether myostatin genotypes are associated with muscular development and cardiac variables of Thoroughbreds. Echocardiography and muscular ultrasonography were performed on three groups having C/C, C/T, and T/T genotypes, respectively. Each group consisted of 22 animals. Homogeneity of v...
van Aarde MN, Littlejohn A, Van der Walt JJ.A method was developed for determining the ratio of cardiopulmonary blood volume to stroke volume, in horses. The radioisotope 99 Tc (technetium 99m pertechnetate) was injected into the jugular vein as a bolus, which was then detected in the right and left ventricles consecutively by a scanning device consisting of a Na I crystal, a collimator, an amplifier and a discriminator. The radiocardiogram (RCG) and the ECG were recorded simultaneously by a two-channel writing device. The ratio of cardiopulmonary blood volume to stroke volume (cardiopulmonary flow index = CPFI) was then determined from...
Bertone JJ, Paull KS, Wingfield WE, Boon JA.M-mode echocardiographic structures, and cardiac function indices, PCV, and total plasma protein values were determined for 34 endurance equine athletes before (base line) and after (after race) a 161-km endurance competition and were compared. The PCV (base-line mean, 37%; after-race mean, 46%) and total plasma protein value (base-line mean, 6.9 g/dl; after-race mean, 7.5 g/dl) increased. Compared with base-line echocardiography, after-race echocardiography indicated an increase in heart rate, as determined from the simultaneous ECG recorded on the echocardiograph (base-line mean, 41 beats/mi...
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...
Traub-Dargatz JL, Schlipf JW, Boon J, Ogilvie GK, Bennett DG, Wingfield WE, Hutchison JM.Ventricular tachycardia develops less frequently than supraventricular dysrhythmias and generally is more indicative of cardiac disease. The horse in this report had clinical signs of lethargy and hypophagia and was determined to have sustained ventricular tachycardia. Echocardiography was a valuable diagnostic tool and revealed an echodense area in the left ventricle that had subnormal ventricular performance. A primary heart problem of an inflammatory nature was suspected. The horse responded favorably to treatment with lidocaine, antimicrobials, and aspirin, as well as stall rest. The horse...
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 ...
Khalesi H, Sakha M, Veshkini A, Rezakhani A.Heart murmurs and valvular regurgitation are common in horses and often have no effect on their performance. However, when structural changes occur in the heart size, they can affect performance adversely. This study aimed to examine the correlation between cardiac valves disease and poor performance in athletic horses. A total of 300 athletic Thoroughbred and mix-breed horses including 164 mares and 136 stallions, with a history of poor performance, were selected. Horses with cardiac murmurs were identified and further cardiac examination including precise auscultation, base-apex electrocardi...
Maxson-Sage A, Parente EJ, Beech J, Lindborg S, May LL, Teleis DC.To determine the effect of exercise on arterial blood gas tensions and upper airway and cardiac function in clinically normal Quarter Horses and horses heterozygous and homozygous for hyperkalemic periodic paralysis (HYPP). ANIMALS AND PROCEDURE: 5 clinically normal Quarter Horses, and 5 heterozygous and 2 homozygous HYPP-affected horses were examined before, during, and after exercise on a high-speed treadmill. Arterial blood gas tensions, ECG, and echocardiogram were obtained prior to exercise. Upper airway endoscopy, collection of arterial blood samples, and continuous electrocardiography w...
Reef VB, Mann PC, Orsini PG.M-mode, 2-dimensional, and contrast echocardiographic studies were used to detect tricuspid atresia in 2 foals. M-mode echocardiographic findings included a small right ventricle, large left ventricle, large mitral valve excursion, large left atrium (foal 2), dropout of the cranial aspect of the aortic root, and a thick band of echoes in the tricuspid valve region. These findings were confirmed by 2-dimensional echocardiography. In addition, a large right atrium, persistent foramen ovale, ventricular septal defect, and large mitral valve apparatus were imaged. One foal also had a thick right a...
Thompson JA, Eades SC, Chapman AM, Paulsen DB, Barker SA, McConnico RS.To determine the effects of clenbuterol, at a dosage of up to 3.2 μg/kg for 14 days, PO, on skeletal and cardiac muscle in healthy horses undergoing treadmill exercise. Methods: 12 healthy horses from 3 to 10 years old. Methods: Horses were randomly assigned to a control group (n = 6) or clenbuterol group (6) and received either saline (0.9% NaCl) solution or clenbuterol, PO, every 12 hours for 14 days. Horses were subjected to submaximal treadmill exercise daily during treatment. Muscle biopsy specimens were collected before and after treatment for determination of apoptosis. Echocardiograph...
Vörös K, Holmes JR, Gibbs C.This study was designed to evaluate the accuracy of two-dimensional echocardiography (2DE) in determining the left ventricular volume (LVV) of the horse in vitro. After examining the shape of the left ventricular silicon rubber casts of four equine hearts, two modified Simpson's rule methods (Model A and Model B) as combinations of conical shapes and one biplane area-length method as a single cone (Model C) were chosen for volume calculations. One long axis and three short axis planes were used for linear and area 2DE measurements, respectively. The ventricular length (L) was calculated from t...
Ramos GV, Santos MM, Gava FN, de Lacerda-Neto JC.The effects of conditioning on cardiac function in young horses is still unknown. For this reason, this study evaluated the left ventricular (LV) function of young horses by echocardiography after six weeks of conditioning. Fourteen untrained young purebred Arabian horses were evaluated at rest and after a stress test (ST) before and after a six-week conditioning program. There was an increase in V4 (p < 0.001) after conditioning, as well as a reduction in both heart rate (HR) at rest and peak HR during the ST (p < 0.001). There was also a reduction in internal diameter, along with an in...
Calewaert A, Palarea-Albaladejo J, Coultous R, Capewell P, Hanks E, Decloedt A, van Loon G.MicroRNA (miRNA) has previously been used as a biomarker for cardiac disease in humans and dogs, however, studies in horses are not yet available. Objective: To determine if adult horses with moderate or severe mitral valve regurgitation have a different serum miRNA expression profile compared to healthy controls. Methods: Retrospective cross-sectional. Methods: Serum samples from 77 adult horses with moderate or severe mitral valve regurgitation and 77 healthy control horses were analysed using a commercial cardiac disease-specific miRNA panel previously used in dogs. Results: The commercial ...
Santosuosso E, Léguillette R, Shoemaker S, Baumwart R, Temple S, Hemmerling K, Kell T, Bayly W.Fitness assessment of horses remains challenging. Heart rate variability (HRV) can be used to monitor human athlete's training, but its value is unknown in horses. Objective: The linear domain HRV variables are affected by fitness. Methods: Twelve healthy untrained thoroughbreds were randomly split into a training group (6 weeks of incremental racetrack training) and a control group (no training). Methods: Linear domain HRV variables were analyzed (high frequency [HF], low frequency [LF], their normalized units [Hf, Lf], root mean square of successive differences between beats [RMSSD], Poinc...
