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Topic:Cardiovascular Health
Cardiovascular health in horses encompasses the study of the heart and blood vessels, focusing on their structure, function, and associated disorders. The equine cardiovascular system is responsible for the circulation of blood, delivering oxygen and nutrients to tissues, and removing waste products. Research in this area includes the examination of cardiac anatomy, the electrophysiology of the heart, and common cardiovascular conditions such as arrhythmias, valvular diseases, and heart murmurs. Diagnostic tools such as echocardiography, electrocardiography, and cardiac biomarkers are utilized to assess cardiovascular function and detect abnormalities. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological mechanisms, diagnostic approaches, and therapeutic strategies related to cardiovascular health in horses.
Investigating the TASK1 potassium channel in equine atrial myocardium as a potential treatment target for atrial fibrillation. Atrial fibrillation (AF) is the most common clinically relevant arrhythmia in horses, with limited pharmacological treatment options in both veterinary and human medicine. TASK1 potassium channels represent a promising atrial-selective antiarrhythmic target, but their relevance in horses has not been established. To characterize equine TASK1 (eqTASK1) channels regarding structural conservation, electrophysiological function, pharmacological sensitivity, cardiac expression pattern and in vivo electrophysiological effects of TASK1 inhibition. Methods: Sixteen horses killed for non-cardiovascular...
Auscultation for pre-exercise screening in the horse. To describe the highlights of cardiac auscultation of the equine athlete in the context of pre-exercise screening for cardiac adverse event prevention. Unassigned: Horses. Unassigned: Tutorial description. Unassigned: Description of the highlights of cardiac auscultation of the equine athlete in the context of pre-exercise screening for cardiac adverse event and exercise-associated sudden death prevention. Unassigned: Cardiac adverse events and exercise-associated deaths are problems that affect horses' health, riders' safety, and the public perception of welfare during equestrian sports. Scre...
Left Ventricular Volume Indexing in Athletic Brazilian Sport Horses Using Body Weight. Left ventricular (LV) volume assessment evaluates cardiac size and remodelling in horses. Single-plane Simpson method of discs (SMOD) provides volumetric measurements requiring body size normalization. Objective: We described LV volumes using SMOD in healthy Brazilian Sport Horses (BH) and evaluated thoracic-girth-estimated body weight (BWe) versus scale-measured weight (BWs) for indexing. Methods: Thirty BH horses (15 males, 15 females; 4-16 years) underwent echocardiography. LV end-diastolic (LVEDV), end-systolic volumes (LVESV), and ejection fraction (EF%) were obtained using SMOD. Body wei...
Echocardiographic characteristics and evidence of ventricular remodeling in subclinical insulin-dysregulated Warmblood horses. In humans, systemic hypertension and left ventricular (LV) hypertrophy are common sequelae of metabolic syndrome and pre-diabetes warranting investigation in horses with insulin dysregulation (ID). Objective: To compare echocardiographic variables, non-invasive blood pressure (NIBP), and adipokines between Warmblood (WB) horses with and without ID. Methods: Nineteen client-owned WB horses, 5-15 years of age, presenting for elective procedures were included. Horses had no history of metabolic disease, ID, laminitis, renal or cardiac disease. Methods: Blinded cross-sectional study. Horses were ...
Antinociceptive effects of subcutaneous butorphanol administration in healthy horses. Subcutaneous (SQ) butorphanol administration maintains target plasma concentrations in horses longer than intravenous administration with fewer adverse effects. This study aimed to evaluate whether SQ butorphanol also produces clinically relevant antinociception in healthy horses. Unassigned: In a blinded, randomized, cross-over study, eight horses received 0.1 mg/kg butorphanol or equal volume (0.01 mL/kg) saline SQ in the cervical region. Thermal (TT) and pain pressure (PPT) thresholds at different body locations, along with physiological and behavioral variables, were assessed at baseli...
Comparison of arterial blood pressure and quality of induction and recovery in horses anesthetized with diazepam or guaifenesin co-induction combined with xylazine and ketamine and maintained on isoflurane. The objective of this prospective alternating crossover study was to compare quality of induction and recovery and cardiopulmonary function in horses administered guaifenesin or diazepam as co-induction drugs. Six healthy horses were anesthetized twice to undergo an MRI and surgical biopsies, with 5 wk between treatments. Horses were sedated intravenously (IV) with xylazine, 0.6 mg/kg BW, and IV induction started 4 min later. Group G received guaifenesin, 100 mg/kg BW, over 2 min and ketamine, 2 mg/kg BW, within 1 to 2 min of starting the guaifenesin. Group D received diazepam, 0.1 mg/kg BW, w...
Effects of constant rate infusion of a fixed-dose combination of medetomidine and vatinoxan on sedation, cardiorespiratory variables, and gastrointestinal activity in standing Thoroughbred horses. A fixed-dose combination of medetomidine (MED) and vatinoxan (VTX), a peripherally selective α2-adrenoceptor antagonist, is commercially available, but its constant rate infusion (CRI) has not been evaluated. Objective: To compare the sedative effects, cardiorespiratory variables, and gastrointestinal activity of MED-VTX and MED-atipamezole (ATIP) with MED alone in Thoroughbred horses. Methods: Six healthy Thoroughbreds underwent a blinded three-treatment, three-period crossover study. Horses received MED (7 μg/kg IV; 5 μg/kg/h CRI for 60 min) alone (gM), with VTX (140 μg/kg IV; 100 μg/kg...
Effects of sympathomimetic agents on heart rate variability during general anesthesia in Thoroughbred horses. Heart rate variability (HRV) is widely used as a noninvasive index of autonomic nervous system activity. The objective of this study was to determine whether the administration of sympathomimetic agents alters HRV indices during general anesthesia in Thoroughbred horses. Five healthy Thoroughbred horses were anesthetized with sevoflurane in oxygen. During 2-5 hr of general anesthesia, five treatments were administered to each horse in a randomized order. Two doses (µg·kg·min) of epinephrine (0.1 and 0.5), norepinephrine (0.5 and 1), dobutamine (1 and 5), dopamine (5 and 15), and saline (as ...
Blood pressure, electrolyte and fluid balance in horses with insulin dysregulation after short-term treatment with canagliflozin. Short-term treatment with SGLT-2 inhibitors decreases blood pressure in people with type 2 diabetes. The aim was to investigate the impact of a 3-week treatment with canagliflozin on blood pressure in insulin dysregulated (ID) horses and to study effects on fluid balance. This was a single-centre, randomised, double-blind, placebo-controlled, parallel design study. The primary study evaluated glucose and insulin responses during an oral sugar test, and these results have been published previously. Here we report the effect of canagliflozin treatment on blood pressure, PCV, serum proteins and e...
Effects of two different fluid rates on tissue oxygenation and haemodynamic stability in anaesthetised horses. Perianaesthetic fluid therapy can influence oxygen delivery and tissue oxygenation, yet the optimal fluid rate in horses remains undefined. Objective: To compare two fluid strategies on peripheral tissue oxygenation (StO) and cardiorespiratory variables in isoflurane-anaesthetised horses. Methods: Randomised, controlled, experimental design with two independent groups. Methods: Sixteen euvolemic adult horses undergoing coeliotomy were anaesthetised with xylazine, ketamine, and midazolam, maintained on isoflurane with lidocaine infusion, and randomised to lactated Ringer's solution at 2.5 mL/...
Electrocardiographic recording in horses at rest: a concordance analysis of two methods. Cardiac arrhythmias are frequently detected during routine auscultation in athletic horses. Assessment of their clinical significance requires electrocardiography (ECG) to analyze waveforms and intervals. In recent years, portable ECG devices have been introduced to simplify electrocardiographic examination, offering advantages such as ease of use and the ability to review results via a smartphone. This study evaluated the utility and accuracy of a portable ECG device compared with a standard electrocardiograph. Simultaneous ECG recordings were obtained from 28 healthy adult horses at rest usi...
Agreement between invasive and oscillometric blood pressure measurements during controlled haemorrhage in anaesthetised horses. Defining the reliability of oscillometry (NIBP) for measuring mean arterial pressure (MAP) during normotension and hypovolaemic hypotension could help with cardiovascular monitoring and management in horses anaesthetised in dorsal recumbency. Objective: To assess agreement between NIBP and invasive MAP during normotension and hypovolaemic hypotension in dorsally-recumbent, anaesthetised horses. Methods: Prospective experimental study using 11 horses. Methods: Under isoflurane anaesthesia, blood was removed at 5 mL/kg bwt increments up to 25 mL/kg bwt and returned in a similar fashion. Pair...
Intraoperative monitoring and anaesthetic complications in horses: A secondary analysis of the CEPEF4 multicentre cohort. CEPEF4 provides the most comprehensive contemporary dataset on perianaesthetic risk in horses. Intraoperative complications, monitoring and American Society of Anesthesiologists (ASA)-stratified associations with death remain incompletely described. Objective: To describe monitoring and complication incidence, assess associations with ASA physical status, and compare ASA-stratified mortality by complication status. Methods: Secondary analysis of a prospective, multicentre cohort study. Methods: Data from 47,371 equine general anaesthetics were analysed. Monitoring was described overall and by ...
Cycle length variation assists in differentiation of atrial, ventricular, and sinus arrhythmias in horses at rest. Criteria for arrhythmia classification in horses are insufficient, particularly when differentiating atrial premature complexes (APCs) from sinus arrhythmia (SA). This study investigated RR and PP interval changes between SA, APCs, and ventricular premature complexes (VPCs). Unassigned: 30 resting ECGs were reviewed: 10 each containing SA, APC, and VPC. Sequences of 10 RR and PP intervals were recorded for each arrhythmia (20 events/ECG). Percent RR and PP deviations were calculated (1) between sequential intervals (%ΔSEQPP and %ΔSEQRR, respectively) and (2) compared to averaged baseline int...
Pulsed wave tissue Doppler imaging of the left ventricle in foals: Feasibility, inter- and intra-observer variability and wave pattern over the first days of life. Tissue Doppler imaging (TDI) may improve the assessment of myocardial function in neonatal foals. Objective: To document the feasibility of left ventricular pulsed wave (PW) TDI, inter- and intra-observer variability and wave pattern over the first 5 days of life. Methods: Prospective observational study. Methods: Transthoracic echocardiography was performed in 25 healthy Standardbred foals within the first 24 h after birth (T1), between 60-84 h (T2), and 108-132 h (T3) after birth using right parasternal short-axis (R-LV SAX) and subcostal long-axis views at the mitral annulus, both a...
Plasma Homocysteine Concentrations in Horses with Left-Sided Valvular Heart Disease. In human medicine, homocysteine, a sulfur-containing amino acid, is used as a biomarker reflecting endothelial dysfunction, inflammation, thrombogenesis, oxidative stress and cardiovascular disease. An automated enzyme-cycling assay for homocysteine, established for humans, has been validated and reference ranges have been created for horses. In this study the homocysteine assay was further evaluated by assessing short-term stability (whole blood and plasma samples stored at 4 °C and room temperature for 24 h), long-term stability (two years), the effect of different anticoagulants (lithium h...
First experience with radiofrequency catheter ablation in horses with recurrent, persistent naturally occurring atrial fibrillation. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial fibrillation (AF) in horses. Objective: Isolation of myocardial sleeves in the caudal vena cava or pulmonary veins might reduce the risk for AF recurrence. Methods: Case series. Methods: Records from seven horses with persistent, recurrent, naturally-occurring AF that were treated with three-dimensional electro-anatomical mapping and radiofrequency catheter ablation (RFCA) in order to reduce recurrence risk were reviewed. Mapping of the caudal vena cava was performed...
Effect of lingual gauze swab placement and light exclusion on pulse oximeter agreement with arterial haemoglobin-oxygen saturation derived from blood-gas analysis in healthy anaesthetised horses. To compare peripheral arterial haemoglobin-oxygen saturation values obtained using pulse oximetry (SpO) with and without a lingual gauze swab under ambient light and light-exclusion conditions, with arterial haemoglobin-oxygen saturation derived from arterial blood-gas analysis (SaO). Methods: Prospective method-comparison study. Methods: A group of 60 healthy adult horses undergoing elective general anaesthesia. Methods: In American Society of Anesthesiologists (ASA) physical status classification I-II horses, SpO readings were obtained under six conditions during anaesthesia: no swab, no swa...
Morphological investigation of myocardial sleeves with potential relevance to atrial fibrillation in Norwegian-Swedish Coldblooded Trotters. Myocardial sleeves (MSs) are thin layers of cardiac muscle that extend from the atria into the caval and pulmonary veins. They are recognised as important structures in both initiating and maintaining atrial tachycardia, and especially atrial fibrillation (AF), which is the most clinically important cardiac arrhythmia in horses with a reported prevalence of 1.3-2% in Standardbred racehorses. In contrast, the Norwegian-Swedish Coldblooded Trotter (NSCT) has a much lower prevalence of AF despite experiencing similar physical demands. The purpose of this study was to describe the macro-, and micr...
The Utility and Reliability of Treadmill Tests for Monitoring Thoroughbreds in Training. This study evaluated the reliability of five treadmill protocols that assess heart rate (HR) and blood lactate (Bla) responses in Thoroughbred horses to determine their effectiveness in serving as potential tools for monitoring fitness and the wellbeing of racehorses. Of the five exercise tests, four consisted of repeated interval gallops at constant speeds (8 m/s and 10 m/s) and grade (6°) and one test of a continuous gallop at constant speeds (8 m/s) and grade (6°). Eight hundred and twenty-three gallops in total were performed by 64 horses. The test-retest reliability and absolute agreeme...
Circadian rhythm of heart rate variability in tropical horses: age-associated autonomic alterations and environmental air pollution effects in an urban field setting. Heart rate variability (HRV) reflects autonomic nervous system activity and is influenced by age, environmental conditions, and circadian rhythms. Information regarding these interactions in horses maintained under tropical conditions remains limited. This study aimed to characterize 24-h heart rate (HR) and HRV patterns in horses raised under tropical conditions and to investigate the effects of aging and environmental factors, including air pollution, on autonomic regulation. Unassigned: Fifteen clinically healthy horses aged 4-20 years were allocated to three age groups: 4-7 years, 8-14 yea...
Agreement of a veterinary-specific oscillometric noninvasive arterial blood pressure monitor (SunTech Vet30) with invasive arterial blood pressure in anaesthetised horses. To evaluate agreement between a veterinary-specific oscillometric noninvasive arterial blood pressure monitor and invasive arterial blood pressure (IBP) measurements in anaesthetised horses. Methods: Prospective clinical method-comparison study. Methods: A group of 46 horses undergoing general anaesthesia in dorsal recumbency. Methods: Paired invasive and oscillometric blood pressure measurements were recorded at 15-minute intervals. IBP was measured via a facial artery catheter, and systolic (SAP), diastolic (DAP), and mean arterial pressures (MAP) were recorded. Oscillometric measurements we...
Case report: exercise-associated sudden death in a Thoroughbred racehorse with cardiac lesions. Exercise-associated sudden death (EASD), defined as acute collapse and death in an apparently healthy racehorse during or within ~1 h after exercise, is currently among the top concerns in the racing industry. Cases of EASD with no cause of death identified at necropsy are frequently presumed to be of cardiac origin. In such cases, in addition to a regular necropsy, a cardiac examination protocol is performed that includes a detailed gross examination and microscopic evaluation of 11 regions of the heart. Very often this protocol is unrewarding because there are no microscopic lesions to expl...
Effects of flow-controlled expiration on oxygenation and early recovery in horses undergoing general anaesthesia. FLow-controlled EXpiration (FLEX) has been shown to significantly enhance oxygenation in horses under clinical and experimental conditions. Objective: To compare pulmonary gas exchange during early recovery following general anaesthesia in horses ventilated with FLEX compared with conventional intermittent positive pressure ventilation (IPPV) and to assess recovery characteristics between ventilation modes. Methods: Randomised, crossover in vivo experiments. Methods: Six adult horses underwent two 2-h anaesthetic episodes in a randomised crossover design (FLEX vs. IPPV), separated by a two-wee...
Auscultatory findings and left atrial function as indicators of mitral valve regurgitation severity in horses. Mitral valve regurgitation (MR) is frequently detected in horses, but its classification and prognostication remain challenging. This study investigated whether auscultatory findings and left atrial function are associated with MR severity. Methods: Fifty controls (no/trivial MR) and 101 MR horses (58 mild, 36 moderate, seven severe) were retrospectively evaluated. All were in sinus rhythm and underwent auscultation and echocardiography. Mitral regurgitation severity was graded using a scoring system. Systolic murmur characteristics (duration, type and grade) were recorded. Left atrial functio...
The progression values of heart rate and biochemical plasma parameters during training of 3-years old warmblood stallions for breeding licensing. Physiological adaptation to training in young sport horses remains incompletely characterized, particularly during standardized preparation for breeding licensing. Objective: The aim of this study was to evaluate cardiovascular and plasma biochemical responses to acute exercise and long-term training in three-year-old Czech Warmblood stallions during standardized free jumping exercise. Methods: Thirteen Czech Warmblood stallions were monitored over a 112-day training period. Heart rate parameters (minimum, maximum, and mean) were recorded during standardized free jumping tests. Plasma biochemi...
Feasibility and safety of repeated 23% hypertonic saline boluses for electrical impedance tomography contrast enhancement in anaesthetised horses. Hypertonic saline (HS) has been used to enhance electrical impedance tomography (EIT) cardiac-related signals associated with pulmonary perfusion in other species, but its suitability and physiological effects in horses are unknown. This exploratory study aimed to determine whether intravenous administration of 100 mL of 23% HS produces a detectable change in thoracic impedance in anaesthetised horses, and to evaluate the physiological effects of repeated bolus administration. Six adult horses were anaesthetised twice using total intravenous anaesthesia. Hypertonic saline 23% was administered ...
Signal-averaged electrocardiography in horses: characteristics of ventricular late potentials in healthy Thoroughbreds and horses with cardiac abnormalities. Sudden death in horses, often attributed to lethal arrhythmias, poses significant welfare and economic risks, yet its prediction remains challenging. This study aimed to characterize ventricular micro-potentials using signal-averaged electrocardiography (SAECG) and evaluate their potential for assessing sudden death risk. High-resolution orthogonal X-, Y-, and Z-lead ECGs were recorded in 24 healthy Thoroughbreds (aged 2-31 years), one horse with bupivacaine-induced myocardial injury, and three horses with persistent pathological murmurs. SAECG parameters, including filtered QRS duration (fQRS...
Evidence of Physiological Comodulation During Human-Animal Interaction: A Systematic Review. This review examines the evidence in the literature for physiological co-modulation during human-animal interaction, identifying studies that assessed comodulation via simultaneous measurement of physiological signals in both species, performing quantitative comparisons. We searched (last search: August 5, 2025) PubMed, EMBASE, Scopus, Google Scholar, Animal Studies Repository, Cochrane, and the Consensus App academic search engine. Risk of bias was assessed using an adapted version of the ROBINS-I V2 tool. The results, grouped by data analysis method, interaction context, and physiological pa...
Comparative cardiac histopathology and toxicology screens in horses succumbing to exercise-associated sudden cardiac death and control horses. Horse racing has faced increased scrutiny because of concerns about equine welfare and the safety of both equine and human participants. Sudden death (SD) in racehorses is relatively uncommon, and its causes are still unclear. Little information and considerable confusion exist regarding the clinical significance of microscopic lesions in the hearts of horses with SD. We examined the hearts of 29 horses that suffered exercise-associated sudden cardiac death (EASCD) and 29 clinically healthy control horses that were euthanized because of catastrophic musculoskeletal injuries. Acute cardiomyocyt...
