Electrocardiography (ECG) in horses is a diagnostic tool used to assess the electrical activity of the heart. It involves recording the electrical impulses that govern heartbeats, providing insights into cardiac function and rhythm. This non-invasive method is useful for identifying arrhythmias, conduction disturbances, and other cardiac abnormalities in equine patients. Electrocardiography can be performed at rest or during exercise to evaluate cardiac performance under different physiological conditions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodology, interpretation, and clinical applications of electrocardiography in equine health.
Darke PG, Holmes JR.The paper describes the use of a four-electrode cancellation technique, employing a bridge circuit to cancel mirror-image ECGs on the body surface of six horses. The axes joining points at which good cancellations were obtained were plotted on planar diagrams. Evidence is presented which suggests that a considerable proportion of cardiac activity could be regarded as though arising from the activity of a single resultant dipole although there is probably some mobility of the dipole centre during different parts of the cardiac cycle.
Holmes JR, Alps BJ.The paper describes the changes in P, QRS and T vector orientations in the H plane in the aberrant beats in cases of partial atrioventricular block and premature atrial and ventricular systoles. The sites of possible atrial ectopic foci are discussed in relation to the anatomy of the atrial chambers and the orientation of the P vectors associated with atrial ectopic beats.
Holmes JR, Alps BJ.The paper describes observations on the distributions of the P, QRS and T cardiac vectors in the horizontal plane, comparing healthy horses with those with arrhythmia and cardiac murmurs. Deviation of the T vector from the normal range appeared to occur most commonly in association with cardiac murmurs, particularly those involving the semilunar valves and aorta.
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.
Holmes JR, Alps BJ.Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed.
The effects of cryopreservation on the acrosomal status of equine spermatozoa were investigated. Ejaculates (n=10) from six stallions were processed fresh, after cooled storage at 4-6 degrees C for 24 h in either a milk-based or lactose-EDTA freezing extender and after freeze-thawing in lactose-EDTA extender in liquid nitrogen at either 5 x 10(7) or 2 x 10(8) spermatozoa ml(-1). All samples were incubated in TALP-TEST for 2 h at 39 degrees C in 5% CO2. Subsamples were challenged with calcium ionophore A23187 for 10 min. The acrosomal status of the spermatozoa was evaluated by staining the sper...
Rankins EM, Faremi BE, Hartmann K, Quinn A, Posada-Quintero HF, McKeever KH, Malinowski K.Heart rate variability (HRV) can be measured as an indicator of autonomic nervous system (ANS) balance and thus, stress and affective arousal. Mixed results have been reported in the limited literature addressing the effects of equine-assisted services (EAS) on HRV in the human and horse participants. The aims of the present study were to determine the effects of ground-based adaptive horsemanship (AH) lessons on veterans' and horses' HRV during weekly lessons as well as veterans' resting HRV outside of lessons. Veterans with post-traumatic stress disorder (PTSD) were randomly assigned to 8 w...
Hartwig S, Rankovic A, McCrae P, Gagliardi K, Burron S, Ellis J, Ma DWL, Shoveller AK.Behavioural reactivity in horses poses a welfare and safety risk to both the horse and the handler, however, beneficial effects have been observed when dietary fat is increased in replacement of sugar. Supplementation with the fatty acids (FA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) appear to improve negative behaviours in rodents and humans, but the effect of α-linolenic acid (ALA), EPA, and DHA, specifically, on reactivity in horses is unknown. The objective of this study was to evaluate the effects of camelina oil (CAM; ALA-enriched) and a mix of camelina and algal oil (ALG; ...
Vitale V, Velloso Álvarez A, de la Cuesta-Torrado M, Neira-Egea P, Vandecandelaere M, Tee E, Gimeno M, van Galen G.In human medicine, neurological diseases have been associated with transient cardiac abnormalities. In horses, myocardial disease is rarely diagnosed and has been associated with a wide variety of causes. The aim of this article is to describe three horses with no previous cardiac disease, which all developed severe cardiomyopathy following neurological disease. A 5-year-old Shetland pony stallion was diagnosed with cardiomyopathy with arrhythmias following an episode of seizures caused by an accidental intra-arterial xylazine injection. A 20-year-old crossbred mare was hospitalised for an ope...
Liu J, Baumwart R, Kwon S.Ventriculophasic response (VR) in atrioventricular nodal (AVN) block is characterized by a shortening of the sinoatrial cycle length when a QRS complex is interposed between two P waves. This has been well documented in humans and dogs with AVN blocks but not in horses. Herein, we describe a horse with second-degree AVN blocks and constant PR intervals that exhibited 5:3 conduction and suspected VR at rest but less consistently after submaximal exercise. Proposed VR mechanisms include (1) inhibition of the Bezold-Jarisch reflex from reduced end-systolic volume during ventricular contraction; (...
Schneider MJ, Piotrowski IL, Junge HK, van Steenkiste G, Vernemmen I, van Loon G, Schwarzwald CC.Left atrial mechanical dysfunction is common in horses following the treatment of atrial fibrillation (AF). This study aimed to evaluate the use of an acoustic cardiography monitor (Audicor) in quantifying cardiac mechanical and hemodynamic function in horses with AF before and after treatment and to correlate these findings with echocardiographic measures. Twenty-eight horses with AF and successful transvenous electrical cardioversion were included. Audicor recordings with concomitant echocardiographic examinations were performed one day before, one day after, and two to seven days after card...
Kisilevich Q, O'Connor SGP, Bayly WM, Léguillette R.To validate a single-lead ECG fitness tracker device (FT) against the reference multilead ECG recording device (RM) for heart rate (HR) and HR variability (HRV) monitoring of horses during routine swimming. Unassigned: 40 race-fit Thoroughbred racehorses were used for 5 days in May 2024. Surface ECG recordings were obtained simultaneously from the FT and RM devices in horses swimming 63.65 m across a pool. Electrocardiograms were reviewed and artifacts corrected when necessary, and correlations were analyzed between the 2 devices for HR and HRV parameters. Descriptive statistics and Bland-Altm...
Rollet M, Flyps J, Vernemmen I, van Loon G, Schauvliege S.Hyperkalaemia is an uncommon complication of general anaesthesia in healthy horses. This case report describes the occurrence of life-threatening acute hyperkalaemia in a 13-year-old, female French Trotter anaesthetised for experimental right and left atrial 3D electro-anatomical mapping. Intra-operative development of hyperkalaemia (7.55 mmol/L) (Ref. 3.00-4.00 mmol/L) with atrial standstill on ECG necessitated transvenous ventricular pacing while initial treatment with insulin and glucose was initiated. Plasma potassium levels continued to increase (8.00 mmol/L) prompting adjunctive tr...
Paulussen E, Delhaas T, Decloedt A, van Loon G, Van Steenkiste G.Twelve-lead electrocardiography (ECG) is essential in human cardiology but remains poorly investigated in equine medicine due to a lack of standardization and inconsistent findings. Objective: Describe the normal vectorcardiogram (VCG) variation in horses at rest and during exercise using Delta 12-lead ECG, including repeatability and intra- and interobserver variations. Methods: One hundred two healthy Warmblood horses, aged 3-20 years, were examined at rest, of which 30 also during exercise. Methods: Prospective, observational study. Electrocardiograms were recorded using a Δ 12-lead confi...
Avison A, Pyle WG, Sears W, Physick-Sheard PW.Sudden cardiac death is a leading cause of athletic death in both humans and horses, making racehorses a potentially valuable model for investigating sudden cardiac death. Cardiac restitution ratio (QT/TQ interval) is used to assess arrhythmia risk in humans, but investigations in athletes are scarce. The objective was to characterize QT interval and cardiac restitution ratio in Thoroughbred racehorses during maximal effort. Automated restitution analysis was performed using 2709 pairs of cardiac cycles from 30 Thoroughbred horses during races. Cardiac cycles were obtained during: pre-race; ac...
Alexeenko V, Tavanaeimanesh H, Stein F, Gold J, Hughes L, McCue M, Marr C, Durward-Akhurst S, Jeevaratnam K.Cardiac arrhythmias are common in healthy athletic horses and may lead to poor athletic performance or exercise-associated sudden death. Early detection of high-risk horses is an important goal of cardiovascular diagnostics. We hypothesised that non-linear analysis of electrocardiogram disorderliness can be used to identify horses exhibiting intermittent ectopic atrial and ventricular heart rhythm abnormalities at exercise using brief, artifact-free recordings of normal sinus rhythm electrocardiograms collected at submaximal heart rates. In a convenience prospective cross-sectional study, ambu...
Buschmann E, Van Steenkiste G, Bulckens H, Schauvliege S, Decloedt A, van Loon G.Frequent premature atrial complexes (PACs) can increase the risk of atrial fibrillation or atrial tachycardia, and pharmacological therapy can be challenging. Objective: To report the use of three-dimensional electro-anatomical mapping of PAC originating from the right atrial free wall and treatment by radiofrequency ablation in three horses. Methods: Retrospective case report. Methods: Frequent premature atrial complexes (PACs) were diagnosed in three horses. Twelve-lead ECG and vectorcardiography suggested an origin in the right lateral free wall in two horses and the caudal right atrium in ...
Avison A, Goderre BG, Pyle WG, Physick-Sheard PW.Sudden cardiac death is common in racehorses. Factors associated with the QT interval that could predispose to fatal cardiac arrhythmias are unknown. Cardiac restitution, expressed as a ratio of QT/TQ, has been used in humans to assess arrhythmia risk but has not been described in horses during maximal intensity exercise. Objective: Describe factors associated with the QT interval and cardiac restitution ratio (CRR) in clinically normal Standardbred racehorses under race-day conditions. Methods: Archival electrocardiograms from 42 Standardbred horses during live racing in Ontario. Methods: Obs...
Buschmann E, Van Steenkiste G, Vernemmen I, Demeyere M, Schauvliege S, Decloedt A, van Loon G.Detailed characterization of arrhythmias can be performed by multiple catheter mapping; but this has not yet been explored in horses. Objective: Perform ultrasound-guided multiple catheter mapping of the right heart during sinus rhythm and right and left atrial pacing to identify activation patterns characteristic of the origin of ectopy. Obtain His signals and effective refractory periods (ERP). Methods: Eight healthy adult horses. Methods: Experimental study. Recording catheters were placed at the terminal crest, intervenous tubercle, caudal vena cava, and coronary sinus. Right atrial pacing...
Dufourni A, Demeyere M, Vernemmen I, Van Steenkiste G, Verhaeghe LM, van Loon G, Decloedt A.Administration of N-butylscopolammonium bromide (NBB) with metamizol sodium (NBBM) causes tachycardia and hypertension, and has been associated with accentuated cardiac murmurs. Objective: To evaluate the effect of a pharmacological challenge using NBBM on valvular regurgitation and cardiac murmurs in horses with aortic (AR) and mitral valve regurgitation (MR). Methods: Twenty Warmblood horses with AR and 20 with MR. Methods: Cardiac auscultation and two-dimensional (2D), M-mode, color flow, pulsed wave Doppler flow, and tissue Doppler echocardiography were performed with simultaneous ECG reco...
Sande A, Santosuosso E, Scharf JE, Shoemaker SJ, Temple S, Hemmerling K, Kell T, Leguillette R, Bayly WM.To compare maximal lactate steady-state (MLSS) speeds determined using a treadmill-dependent invasive reference method (RM) with 2 noninvasive methods based on heart rate variability-focused analysis of exercise ECGs. Unassigned: This was a randomized, blinded study using 7 fit Thoroughbreds. A standardized incremental exercise treadmill test (SET) where blood lactate concentration ([La]) was measured after every step facilitated calculation of speeds at which [La] was 1.5, 2.0, and 2.5 mmol/L. The RM required steady-state exercise (SS) at each of these speeds for 25 minutes or until [La] incr...
A Mangalarga Marchador mare was referred to treatment with a history of poisoning with evident tachyarrhythmia detected on cardiac auscultation. The electrocardiogram was performed and detected occurrences of paroxysmal monomorphic ventricular bigeminy (pMVB), pMVB with pairs of premature ventricular contractions (PVC) (pMVBPC), and paroxysmal monomorphic ventricular tachycardia (pMVT). In all cases, incomplete atrioventricular dissociation and coupling variation are observed. These characteristics, associated with non-reduction of successive subsequent coupling intervals and the absence of ty...
Giannone C, Atallah E, Dalla Costa E, Benetti E, Santolini E, Tassinari P, Bovo M.Technology for monitoring behaviour and health of horses has evolved significantly, presenting new opportunities and challenges in equine management and healthcare. This scoping review consolidates recent findings on wearable sensors and non-contact technologies, discussing their benefits and limitations. Among these advancements, heart rate monitors stand out as a key point in equine monitoring. By tracking heart rate variability, devices help monitor cardiac autonomic regulation, optimise training regimens and allow early detection of cardiac issues, although accuracy can be compromised by i...
McCrae P, Spong H, Moorehead J, Pearson W.A smart textile device has been developed for the recording of electrocardiograms (ECGs) in horses; however, the utility of this device for long-duration heart rate variability (HRV) monitoring and detection of physiological arrhythmias is unknown. Therefore, the objective of this study was to validate a smart textile device for HRV over long durations (6 h) in resting horses. ECGs were recorded simultaneously via the Myant Skiin Equine textile device and a reference device (Televet 100) in 12 horses. ECGs were evaluated by a blinded observer for arrhythmias, and HRV metrics were calculated. ...
Alexeenko V, Anchan DS, Ter Woort F, Ribonnet C, van Erck E, Marr C, Jeevaratnam K.Non-linear equine electrocardiography (ECG) analysis is an actively developing study area which has the potential to lead to novel, artificial intelligence-based diagnostic tools in equine cardiology. As more ECG recording devices are becoming available, there is a need to ensure results are interchangeable regardless of the equipment used to record the equine ECG. Objective: To evaluate the agreement of ECG complexity values obtained using the Televet™ and Equimetre™ systems. Methods: Cross-sectional clinical. Methods: ECGs were recorded using two devices simultaneously from 37 healthy Th...
Shroff K, Underwood C, Stefanovski D, Hopster K, Slack J.To determine transthoracic impedance (TTI) in adult horses using an exponential biphasic defibrillator and investigate patient and technique factors influencing TTI. Unassigned: A randomized crossover design with 2 phases was used. Phase 1: TTI was measured in dorsal and lateral recumbency, with and without manual pressure on the electrodes in deceased horses immediately following euthanasia. Phase 2: TTI was measured in dorsal recumbency during inspiration and expiration using anesthetized live horses sourced from 2 terminal studies. Mixed-effects linear regression modeling was performed to a...
Kapusniak A, Lara NM, Hitchens PL, Bailey S, Nath L, Franklin S.Artificial intelligence (AI) is increasingly used to enhance electrocardiogram (ECG) interpretation in human medicine. In equine athletes, exercise-associated arrhythmias are common and linked to sudden cardiac death at rates higher than in humans. However, ECG interpretation in horses remains time-consuming and subjective, with the clinical relevance of mild rhythm disturbances often unclear. Objective: Evaluate the application of AI to ECG interpretation for arrhythmia detection, with emphasis on current and potential use in athletic species, particularly horses. Methods: About 17 studies we...
Smith CM, Weimann K, Widick M, Merritt T, Christensen H, Siegel M, Pan Z, Gabriels RL.The purpose of this paper is to serve as a catalyst for the human-animal interaction research field to improve scientific rigor and accelerate the knowledge of field-based physiological responses during equine-assisted services in youth with autism spectrum disorder. This paper outlines the best practices for collecting and analyzing electrocardiogram and electrodermal activity in youth with autism spectrum disorder, utilized during a 10-week therapeutic horseback riding intervention.•Motivation strategies such as device choice, reward systems, and a visual schedule should be implemented to ...
