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.
Heterospecific Fear and Avoidance Behaviour in Domestic Horses (Equus caballus). Ridden horses have been reported to be fearful of cows. We tested whether cows could provoke behavioural and cardiac fear responses in horses, and whether these responses differ in magnitude to those shown to other potential dangers. Twenty horses were exposed to cow, a mobile object or no object. The time spent at different distances from the stimulus was measured. In a separate test, heart rate (HR), root mean square of successive differences between heartbeats (RMSSD) and the horses' perceived fear were assessed at various distances from the stimuli. The horses avoided the area nearest to a...
Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation. Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis ...
Effect of thermodilution injectate volume and temperature on the accuracy and precision of cardiac output measurements for healthy anesthetized horses. To compare the accuracy and precision of cardiac output (CO) measurements derived from 4 thermodilution protocols that used different injectate temperatures and volumes in healthy adult horses. Methods: 8 healthy adult horses. Methods: Horses were anesthetized and instrumented with Swan-Ganz catheters. The CO was derived from each of 4 thermodilution protocols (IV injection of physiologic saline [0.9% NaCl] solution chilled to < 5 °C at volumes of 1 mL/15 kg of body weight [protocol A; control], 1 mL/25 kg [protocol B], and 1 mL/35 kg [protocol C] or maintained at 17 °C at a volume of 1 m...
Preliminary study on the effects of pergolide on left ventricular function in the horses with pituitary pars intermedia dysfunction. Pituitary pars intermedia dysfunction (PPID), a neurodegenerative disease leading to reduced dopamine production, is a common disease in aged horses. The treatment is based on administration of the dopamine agonist pergolide. This drug has been related to valvular fibrosis in humans, but the cardiovascular effect of this drug has not yet been investigated in horses. Objective: To determine whether pergolide induces valvular disease in horses or affects the cardiac function. Methods: Standard, tissue Doppler (TDE) and two-dimensional speckle tracking (STE) echocardiography were performed in hor...
Cardiopulmonary function and intestinal blood flow in anaesthetised, experimentally endotoxaemic horses given a constant rate infusion of dexmedetomidine. Endotoxaemia causes untoward inflammatory-mediated effects that might be attenuated by dexmedetomidine. Objective: To evaluate the effects of a dexmedetomidine intravenous (IV) infusion on systemic and intestinal haemodynamics and arterial blood gas values in sevoflurane-anaesthetised horses administered Escherichia coli O55:B5 lipopolysaccharides (LPS). Methods: Randomised controlled in vivo experiment. Methods: A total of 13 horses weighing 456 ± 86 kg (mean ± standard deviation) and aged 13.9 ± 9.0 years donated for euthanasia underwent ventral midline celiotomy using sevoflurane...
A Preliminary Investigation into Ridden Water Submersion Training as an Adjunct to Current Condition Training Protocols in Performance Horses. This observational study aimed to elucidate the effects of RWST on the cardiovascular and musculoskeletal systems of horses and concurrently determine whether RWST limits distal limb temperature increases previously reported during gallop training on land. A group of 15 clinically sound international event horses were recruited, and heart rate (HR), speed (km/h) and thermal images of the distal limb were analysed at set intervals during RWST training. Intervals of RWST produced a total mean HR value of 65.18 ± 3.76%, which is within the parameters for increased aerobic stamina. Mean HR increa...
Effect of a long-term high-energy diet on cardiovascular parameters in Shetland pony mares. Changes in cardiovascular parameters, including blood pressure (BP) and cardiac anatomical dimensions, are an inconsistent feature of the equine metabolic syndrome. The order in which these changes arise is unknown. Objective: Determine the order in which EMS-associated changes in cardiovascular parameters arise. Methods: Twenty Shetland pony mares. Methods: High-energy (HE) diet mares were fed 200% of net energy requirements for 1 (n = 3) or 2 (n = 7) consecutive diet-years, with 17 weeks of hay-only between years. Noninvasive BP measurements and echocardiograms were performed during bo...
Evaluation of a new portable 1-lead digital cardiac monitor (eKuore) compared with standard base-apex electrocardiography in healthy horses. Recently, the use of smartphone ECG devices has been reported in humans and animals. Nevertheless, as the electrodes of these devices are inseparable, they can create only a precordial reading in veterinary species. Thus, although the smartphone ECG devices are considered valuable as a screening tool for the detection of some common arrhythmias, they are not always a reliable method for the measurement of the duration of the electrical deflections. The objectives of this study were to evaluate the feasibility of a novel smartphone ECG device, to report the readings obtained recorded simultaneo...
A randomised, controlled trial to determine the effect of levothyroxine on Standardbred racehorses. The use of thyroid supplement is pervasive in athletic horses although its effects on measures of performance are not known. Objective: One purpose of this study was to determine whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was greater than 4 mmol/L (VLa4 ) and heart rate was over 150 (V150 ) and 200 (V200 ) beats per minute respectively. Additionally, a survey of post-race blood samples was also conducted to determine whether high thyroxine concentrations were common in racehorses. Methods: A randomised, crossover, trial was performed in six h...
Total Intravenous Anaesthesia with Ketamine, Medetomidine and Midazolam as Part of a Balanced Anaesthesia Technique in Horses Undergoing Castration. To evaluate the use of ketamine-medetomidine-midazolam total intravenous infusion as part of a balanced anaesthetic technique for surgical castration in horses. Five healthy Standardbred cross colts were premedicated with IV acepromazine (0.01-0.02 mg/kg), medetomidine (7 µg/kg) and methadone (0.1 mg/kg) and anaesthesia induced with IV ketamine (2.2 mg/kg) and midazolam (0.06 mg/kg). Horses were anaesthetised for 40 min with an IV infusion of ketamine (3 mg/kg/h), medetomidine (5 µg/kg/h) and midazolam (0.1 mg/kg/h) while routine surgical castration was performed. Cardiorespiratory variables...
Accuracy of a heart rate monitor for calculating heart rate variability parameters in exercising horses. Heart rate is evaluated in exercising horses to monitor the level of fitness to exercise, and it is usually acquired using heart rate monitors (HRM) or telemetric electrocardiograms (ECG). While HRM are commonly available and easy-to-use for horse's owners, ECG is a more expensive equipment requiring user's experience. Interest for heart rate variability (HRV) in horses is increasing for both research and clinical purposes. HRV is usually calculated from interbeat intervals (IBI) obtained by ECG. The aim of this study was to determine the accuracy of an HRM to detect IBI for the calculation of...
Histological and biomechanical properties of systemic arteries in young and old Warmblood horses. Arterial rupture is a well-recognized cause of sudden death in horses, which mainly affects older horses. The arterial wall is known to stiffen with age, although the underlying age-related histological and biomechanical changes remain unclear. The purpose of this study was to investigate the effect of aging by histological analysis of the arterial wall and examination of the arterial wall biomechanical properties using an inflation-extension test. Entire circular samples of the proximal and distal aorta, cranial and caudal common carotid, external iliac, femoral and median artery were collect...
Causes, Effects and Methods of Monitoring Gas Exchange Disturbances during Equine General Anaesthesia. Horses, due to their unique anatomy and physiology, are particularly prone to intraoperative cardiopulmonary disorders. In dorsally recumbent horses, chest wall movement is restricted and the lungs are compressed by the abdominal organs, leading to the collapse of the alveoli. This results in hypoventilation, leading to hypercapnia and respiratory acidosis as well as impaired tissue oxygen supply (hypoxia). The most common mechanisms disturbing gas exchange are hypoventilation, atelectasis, ventilation-perfusion (V/Q) mismatch and shunt. Gas exchange disturbances are considered to be an import...
Performance of the Parasympathetic Tone Activity (PTA) index to predict changes in mean arterial pressure in anaesthetized horses with different health conditions. The parasympathetic tone activity (PTA) index is based on heart rate variability and has been developed recently in animals to assess their relative parasympathetic tone. This study aimed to evaluate PTA index in anaesthetized horses with different health conditions and the performance of PTA variations (∆PTA) to predict changes in mean arterial pressure (MAP). Thirty-nine client-horses were anaesthetized for elective or colic surgery and divided into "Elective" and "Colic" groups. During anaesthesia, dobutamine was administered as treatment of hypotension (MAP <60 mmHg). In both groups, no...
Pharmacodynamics and plasma concentrations of dexmedetomidine with or without vatinoxan as a constant-rate infusion in horses anaesthetized with isoflurane-A pilot study. The aim was to determine the effects of vatinoxan on dexmedetomidine plasma concentrations and effects on cardiovascular and intestinal tissue pharmacodynamics. In a prospective randomized study, six horses were premedicated intravenously with dexmedetomidine 3.5 µg kg followed by a constant-rate infusion of 7 µg kg h (group DEX) and six horses with dexmedetomidine of the same dose (bolus and constant-rate infusion) combined with vatinoxan 130 µg kg followed by 40 µg kg h (group VAT). Anaesthesia was induced with ketamine and diazepam and maintained with isoflurane. Venous bloo...
Exercise-Associated Sudden Death in Finnish Standardbred and Coldblooded Trotters – A Case Series With Pedigree Analysis. Exercise-associated sudden deaths (EASDs) are deaths occurring unexpectedly during or immediately after exercise. Sudden cardiac death (SCD) is one cause of EASD. Cardiac arrhythmias caused by genetic variants have been linked to SCD in humans. We hypothesize that genetic variants may be associated with SCD in animals, including horses. Genetic variants are transmitted to offspring and their frequency might increase within a family. Therefore, the frequency of such variants might increase with the inbreeding factor. Higher inbreeding could have a negative impact on racing performance. Pedigree...
Evaluation of Different Blood Parameters From Endurance Horses Competing at 160 km. The purpose of this study was to assess a change in different blood parameters before and after a 160 km endurance race and to evaluate differences in cardiac biomarkers between horses that completed the race and horses that did not. The study population consisted of 52 healthy endurance horses. Horses participating in the study were assigned to three groups: horses that successfully completed the race ("finishers"), horses that failed to qualify at the veterinary check for primarily metabolic reasons ("metabolic") and horses that failed to qualify at the veterinary check for primarily gait re...
The effect of xylazine on intracranial pressure in anesthetized and standing horses. To determine the effect of xylazine on intracranial pressure (ICP) in standing compared to isoflurane-anesthetized horses. Methods: Prospective, crossover study design. Methods: University Teaching Hospital. Methods: Six adult horses donated to the University. Horses were determined to be healthy via physical examination, complete blood count, and neurological evaluation. Methods: Horses were anesthetized, maintained on isoflurane in oxygen in left lateral recumbency, and ventilated to normocapnia. Horses were instrumented for intraparenchymal measurement of ICP, invasive blood pressure, pulse...
Blood lactate concentrations and heart rates of Colombian Paso horses during a field exercise test. Information on performance indices in Paso horses is scarce. Field exercise tests are necessary to recreate the exertion that occurs during training and competition. To describe blood lactate concentrations and heart rates of untrained Colombian Paso horses (CPHs) in response to a field exercise test. A 30-minutes-long standardized field exercise test was carried out on 11 untrained adult CPHs of both sexes. Blood lactate concentration (BLConc) and heart rate (HR) were measured before, during each step of the test, and at recovery. The BLConc and HR were used to calculate the HR at which a BLC...
The use of electrical impedance tomography (EIT) to evaluate pulse rate in anaesthetised horses. Electrical impedance tomography (EIT) provides clinically useful lung images; however, it would be an advantage to extract additional cardiovascular information from the data. The aim of this study was to evaluate if cardiac-related changes measured by EIT can be used to measure pulse rate (PR) under physiological as well as high and low blood pressure states in anaesthetised horses. Electrical impedance tomography data and PR from seven horses anaesthetised in dorsal recumbency were recorded over 1 min during mechanical ventilation and 1 min of apnoea. Data were collected at four measurement ...
Balloon valvuloplasty of valvular pulmonary stenosis in a neonatal foal. In a 1-day old filly with a loud heart murmur, transthoracic echocardiography revealed right ventricular hypertrophy associated with severe pulmonary valvular stenosis and a transvalvular pressure gradient (between right ventricle and pulmonary artery) of 125 mmHg. Computed tomographic angiography confirmed the finding, with no evidence of other relevant concurrent abnormalities. Balloon valvuloplasty was performed using a single balloon technique. The foal recovered well from anaesthesia. Following the procedure, the right ventricle-pulmonary artery transvalvular gradient decreased to 38 mm...
Effects of head position on internal and external carotid pressures in standing sedated horses. The effects of head position on internal carotid artery (ICA) and external carotid artery (ECA) pressures in standing sedated horses were evaluated in this study. The common carotid artery (CCA) was catheterized in 6 horses using an ultrasound-guided technique to facilitate placement of a pressure transducer within the ICA and ECA at the level of the guttural pouch. Transducer position was confirmed by endoscopic visualization. Mean arterial pressure (MAP) was measured with horses in both a head-up and head-down position. The dorsal metatarsal artery was catheterized as a control. Maintaining ...
Rider Energy Expenditure During High Intensity Horse Activity. Despite the fact that horseback riding is a popular sport, there is little information available on horseback riding as a physical activity. The objective of this experiment was to quantify energy expenditure of participants (n=20) during three riding tests: a 45min walk-trot-canter ride (WTC), a reining pattern ride and a cutting simulation ride while wearing a telemetric gas analyzer. Total energy expenditure (tEE), mean and peak metabolic equivalents of task (MET), heart rate (HR), respiratory frequency (RF), relative oxygen consumption (relVO2), and respiratory exchange ratio (RER) were as...
Analgesic and Cardiopulmonary Effects of Epidural Romifidine and Morphine Combination in Horses. The study aim is to compare the effects of epidural administration of two different doses of romifidine combined with morphine in horses. A prospective crossover blinded experimental design was used. Five adult healthy horses two males and three females with a mean body weight of 380 ± 45 Kg (335-425 kg), were studied. Treatments consisted of romifidine 30 μg/kg (R30) or 60 μg/kg (R60) combined with morphine 0.1 mg/kg with a washout interval of 72 hours, administered through an epidural catheter placed at the first intercoccygeal space. Heart rate (HR) and respiratory rate (f), pH, blood ga...
Horse Preferences for Insolation, Shade or Mist Curtain in the Paddock under Heat Conditions: Cardiac and Behavioural Response Analysis. The horse's welfare and, consequently, the emotional arousal may be connected with stressful environmental conditions. This study aimed to determine whether horses show behavioural or physiological symptoms of thermal discomfort and if their behaviour and cardiac parameters are related to freely chosen insolated (IS), shaded (SH), or water sprayed (with a mist curtain (MC)) areas in a paddock under heat conditions (29-32 °C, 42.0 ± 1.5% humidity). Twelve adult horses freely moving in the paddock were studied during a 45 min solitary turnout. Six cardiac variables, locomotor, and non-locomoto...
Quantification of left atrial contractile function using two-dimensional speckle tracking echocardiography in horses after conversion of atrial fibrillation to sinus rhythm. 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...
Prevalence and characteristics of ventricular septal defects in a non-racehorse equine population (2008-2019). Ventricular septal defects (VSDs) are the most common congenital cardiac defect in horses. Objective: To identify prevalence, age, breed, and sex distribution of VSD and to describe associated clinical and ultrasonographic findings. Methods: Hospital-based population of 21 136 horses presented to the equine internal medicine department. Methods: Medical records over a 12-year period were reviewed for VSD confirmed by ultrasonography. Age, breed, sex, sport discipline, murmur, clinical signs, outcome, VSD type, VSD size, shunt velocity, cardiac dimensions, concomitant cardiac anomalies, and v...
Exodontia associated bacteremia in horses characterized by next generation sequencing. Bacteremia resulting from dental surgery is increasingly recognized as a health risk, especially in older and immunocompromised patients. Dentistry-associated bacteremia can lead to remote infections, as exemplified by valvular endocarditis. Emerging evidence points to a novel role played by oral cavity commensals in the pathogenesis of diabetes, respiratory disease, cardiovascular disease, and adverse pregnancy outcomes. Whether dental extraction, a commonly undertaken procedure in old horses, causes bacteremia has not been reported extensively. In a prospective clinical study using next gene...