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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.
Horses and Zebras: complex cardiac anatomy in a patient with out-of-hospital cardiac arrest. This case report describes a woman presenting after out-of-hospital cardiac arrest with several cardiac anomalies, including a form fruste of Ebstein's anomaly complicated by a large tricuspid valve vegetation. On autopsy, she proved to have unstable plaques in epicardial vessels that likely caused arrhythmic sudden cardiac death, a reminder that even in the presence of rare anomalies, common things are common.
Correlation between jugular and central venous pressures in laterally recumbent horses. To compare and correlate right atrial pressure, which represents central venous pressure (CVP) to jugular vein pressure (JVP) in laterally recumbent horses under anesthesia. Methods: Retrospective clinical trial. Methods: Seven adult healthy horses (411 ± 8.7 kg). Methods: Horses were sedated with IV xylazine and anesthesia was obtained with IV ketamine and diazepam. Anesthesia was maintained with sevoflurane in oxygen. All horses were positioned in left lateral recumbency. An 8F catheter introducer was inserted into the right jugular vein to measure JVP. An 8F catheter introducer was i...
Effects of a constant rate infusion of detomidine on cardiovascular function, isoflurane requirements and recovery quality in horses. To examine the influence of a detomidine constant rate infusion (CRI) on cardiovascular function, isoflurane requirements and recovery quality in horses undergoing elective surgery. Methods: Prospective, randomized, blinded, clinical trial. Methods: Twenty adult healthy horses. Methods: After sedation (detomidine, 10 μg kg(-1) intravenously [IV]) and induction of anaesthesia (midazolam 0.06 mg kg(-1) , ketamine 2.2 mg kg(-1) IV), anaesthesia was maintained with isoflurane in oxygen/air (inspiratory oxygen fraction 55%). When indicated, the lungs were mechanically ventilated. Dobut...
Influence of electrode position on cardioversion energy requirements during transvenous electrical cardioversion in horses. To evaluate influence of electrode position on cardioversion energy (CE; energy delivered in the shock at which cardioversion was achieved) during transvenous electrical cardioversion (TVEC) in horses with atrial fibrillation. Methods: 37 horses with atrial fibrillation (41 cardioversion events). Methods: Records were reviewed to identify horses that underwent TVEC for treatment of atrial fibrillation. Signalment and CE were recorded. Electrode positions in the right atrium and pulmonary artery were identified on intraoperative radiographs. An orthogonal coordinate space was created, and elect...
Heart rate and heart rate variability in pregnant warmblood and Shetland mares as well as their fetuses. Heart rate (HR) is an important parameter of fetal well-being. In horses, HR and heart rate variability (HRV) can be determined by fetomaternal electrocardiography (ECG) from mid-pregnancy to foaling. Normal values for physiological parameters in larger breeds are often used as reference values in ponies. However, HR increases with decreasing size of the animal and in ponies is higher than in warmblood horses. It is not known if fetal HR is affected by breed and if values obtained in larger breeds can be used to assess Shetland fetuses. We have determined fetomaternal beat-to-beat (RR) interva...
The pharmacokinetics and pharmacodynamics of the injectable anaesthetic alfaxalone in the horse. To determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin. Methods: Prospective experimental study. Methods: Ten (five male and five female), adult, healthy, Standardbred horses. Methods: Horses were premedicated with acepromazine (0.03 mg kg(-1) IV). Twenty minutes later they received xylazine (1 mg kg(-1) IV), then after 5 minutes, guaiphenesin (35 mg kg(-1) IV) followed immediately by IV induction of anaesthesia w...
Preliminary investigation of concurrent administration of phenylbutazone and romifidine in healthy horses. To characterize the cardiorespiratory and electrocardiographic effects of the combined administration of phenylbutazone and romifidine. Methods: Prospective four-period, four-treatment, blinded, randomized, crossover trial. Methods: Five, healthy, mixed breed horses. Methods: Prior to treatment administration, a catheter was introduced into the intra-thoracic cranial vena cava via the jugular vein and a subcutaneously located carotid artery was catheterised. All treatments were administered intravenously (IV) and consisted of saline placebo (PLC), phenylbutazone (PBZ, 4.4 mg kg(-1) ) romifidin...
Effect of general anesthesia on plasma cardiac troponin I concentrations in healthy horses. To evaluate the effect of general anesthesia on plasma cTnI concentrations in horses. Methods: Thirty-two horses undergoing general anesthesia and either elective surgery or MRI without surgery were prospectively studied. Twenty-nine horses (22 surgical, 7 imaging) completed the study. Plasma cTnI concentrations were determined prior to anesthesia and at 6, 12 and 24 h following discontinuation of the inhalant anesthetic. Results: All horses had cTnI values within the reference range at all time points. Six horses (21%) developed detectable cTnI 6 or 12 h following anesthesia. Risk factors f...
Cardiovascular effects of N-butylscopolammonium bromide and xylazine in horses. N-butylscopolammonium bromide (NBB) and xylazine are commonly used medications for the treatment of spasmodic colic and other forms of abdominal pain in horses. Both NBB and xylazine exert significant effects on the cardiovascular system and other vital systems of horses. Objective: To evaluate the effects of i.v. administration of NBB, xylazine, and the combination of NBB and xylazine on heart rate, other commonly measured physiological parameters, cardiac rhythm and blood pressure. Methods: Six mature horses of mixed breed were used. In a random cross-over design, each horse was given 0.3 mg...
Subclinical diseases underlying poor performance in endurance horses: diagnostic methods and predictive tests. Thirty-eight endurance horses underwent clinical and ancillary examinations, including haematological and biochemical evaluation, standardised exercise tests both on a treadmill and in the field, Doppler echocardiography, impulse oscillometry, video endoscopy and collection of respiratory fluids. All of the examined poorly performing horses were affected by subclinical diseases, and most of them had multiple concomitant disorders. On the contrary, the well-performing horses were free of any subclinical disease. The most frequently diagnosed diseases were respiratory disorders, followed by musc...
Long-term facial artery catheter implantation for serial arterial blood sampling and invasive arterial blood pressure measurement in horses. The purpose of this investigation was to evaluate surgical catheter implantation in the facial artery of horses and the long-term maintenance of such arteries using heparin and ascorbic acid as filling solution. Nine horses were implanted with a polyurethane catheter. The catheters were flushed with a heparin/ascorbic acid solution every 8h and remained patent for 25 days. Arterial blood samples were collected twice a day, and one exercise test that included serial blood samples and arterial pressure recordings was performed on a treadmill. Polyurethane catheters surgically implanted in the fa...
Plasma atrial natriuretic peptide concentrations in horses with heart disease: a pilot study. Atrial natriuretic peptide (ANP) is a cardiovascular biomarker that might be useful in assessing the severity of cardiac disease in horses. Plasma ANP concentrations (Cp(ANP)) were compared between horses with heart disease but normal chamber size and function (Group A; n=6), horses with heart disease associated with left atrial (LA) enlargement, LA dysfunction, and/or left ventricular (LV) enlargement (Group B; n=5), and horses with no clinically apparent cardiovascular disease (Group C; n=13). The median (min-max) for Cp(ANP) was significantly higher in Group B (53.5 (36.0-70.7) pg/mL), comp...
Physiological and blood biochemical variables in horses exercising on a treadmill submerged in water. The blood lactate concentration (LA) and heart rate (HR) of 10 horses exercising in water on a treadmill were examined. With the water at 10 and 50% of the withers height (WH), the blood LA increased up to mean values around 1.9 mm during the standardized exercise test (SET) until after step 3 of 5 (each step lasted 5 min, speed increasing step by step). Thereafter, blood LA of horses remained constant, while with the water at 80% of WH, the blood LA decreased from the mean peak of 2.16 ± 0.62 mm after the 4th step. The HR of the horses increased to 132 ± 14 beats/min until the 3rd step of S...
Cardiac troponin I and the occurrence of cardiac arrhythmias in horses with experimentally induced endotoxaemia. The aim of this study was to determine whether experimentally-induced endotoxaemia induced elevations in plasma cardiac troponin I (cTnI) concentrations in horses and how this might affect the incidence of cardiac arrhythmias. Eight Standardbred horses received an intravenous continuous rate infusion of endotoxin (total dose 500 ng/kg) for 6 h while being monitored using electrocardiography (ECG). Blood samples were collected before the start of the endotoxin infusion, every 60 min during the infusion, then 1, 2, 3, 8, 10 and 24 h post-infusion, and analysed for cTnI concentrations. One horse ...
Altered systolic left ventricular function in horses completing a long distance endurance race. It is unknown whether or not exercise-induced cardiac fatigue (EICF), as demonstrated in human athletes performing long duration exercise, occurs in endurance horses. Objective: To examine the effects of a long distance endurance race on left ventricular systolic function in horses. Methods: Echocardiography was performed before, and after, a 2 or 3 star international endurance race (106-132 km) in 11 horses. Systolic (s) and diastolic (d) interventricular and left ventricular free wall thickness (IVS and LVFW, respectively), left ventricular, left atrial and aortic internal diameter (LVID, LA...
Efficacy of single-dose intravenous phenylbutazone and flunixin meglumine before, during and after exercise in an experimental reversible model of foot lameness in horses. Objective blinded efficacy data during exercise are lacking on the use of single-dose i.v. nonsteroidal anti-inflammatory drugs (NSAIDs) before, during and after exercise. Objective: Single i.v. doses of either phenylbutazone (PBZ) or flunixin meglumine (FM) would prove more efficacious than negative saline control (SAL) before, during and after exercise in a reversible model of foot lameness. Methods: Six Quarter Horse mares had lameness induced by tightening a set screw against a heart bar shoe 1 h prior to treatment. Randomised blinded treatments included PBZ (4.4 mg/kg bwt i.v.), FM (1.1 m...
Plasma aldosterone concentration and cardiovascular response to low sodium intake in horses in training. Horses in training lose large amounts of sodium but little is known about the cardiovascular response to low sodium intake. Objective: To investigate the effect of low sodium intake on plasma aldosterone (pAldo) concentrations and the cardiovascular system of athletic horses, and to identify markers of low sodium intake. Methods: Seven Standardbred geldings in training (trained twice a week) were randomly offered a standardised diet supplemented (NaS, 58 mg Na/kg bwt) and not supplemented (NaN, 3 mg Na/kg bwt) with NaCl for 5 weeks in a changeover design. Blood samples were taken once a week a...
Age related decreases in thermoregulation and cardiovascular function in horses. Older horses have an increased risk of hyperthermia due to impaired cardiovascular function. While many studies have investigated thermoregulation in horses during exercise, none have investigated the effects of ageing. Objective: To test the hypothesis that there is a difference in thermoregulation during exercise and plasma volume (PV) in young and old horses. Methods: Study 1: 6 young (Y, 7.7 ± 0.5 years) and 5 old (O, 26.0 ± 0.8 years) unfit Standardbred mares (507 ± 11 kg, mean ± s.e.) ran on a treadmill (6% grade, velocity calculated to generate a work rate of 1625 watts) until core ...
Cardiac arrhythmias in clinically healthy showjumping horses. Electrocardiographic reference values of clinically normal horses during exercise are a prerequisite when evaluating horses with poor performance or horses presented with cardiac abnormalities (e.g. valvular regurgitation). No published studies have reported cardiac rhythms of clinically normal showjumping horses. Objective: To demonstrate the feasibility of obtaining exercise electrocardiogram (ECG) in normal horses during showjumping and also to document the prevalence and frequency of arrhythmias in association with exercise. Methods: Thirty-four healthy showjumping horses aged 4-13 years (...
Effects of flunixin on cardiorespiratory, plasma lactate and stride length responses to intense treadmill exercise in Standardbred trotters. Since nonsteroidal anti-inflammatory drugs, such as flunixin, on account of their anti-inflammatory and analgesic properties, are used in both racing and equestrian sport horses, the question has been raised as to whether these drugs affect the physiological responses to exercise and thus performance potential. Objective: The aims of this investigation were to study the effects of flunixin on cardiorespiratory, metabolic and locomotor parameters in horses during intense treadmill exercise. Methods: Six Standardbred trotters underwent an incremental treadmill exercise test to fatigue, without d...
Prevalence of exercise-associated arrhythmias in normal performing dressage horses. Exercise-associated arrhythmias are important differentials when evaluating poor performance sport horses. However, most studies of arrhythmias have been conducted in racehorses and therefore there is a paucity of knowledge concerning the prevalence and significance of exercise-associated arrhythmias in riding horses. Objective: The objective of this study was to examine the prevalence of arrhythmias, particularly supraventricular premature complex (SVPCs) and ventricular premature complex (VPCs), associated with exercise in normal performing dressage horses. Methods: In total, 21 normal perfo...
Observer agreement for detection of cardiac arrhythmias on telemetric ECG recordings obtained at rest, during and after exercise in 10 Warmblood horses. Frequent supraventricular or ventricular arrhythmias during and after exercise are considered pathological in horses. Prevalence of arrhythmias seen in apparently healthy horses is still a matter of debate and may depend on breed, athletic condition and exercise intensity. Objective: To determine intra- and interobserver agreement for detection of arrhythmias at rest, during and after exercise using a telemetric electrocardiography device. Methods: The electrocardiogram (ECG) recordings of 10 healthy Warmblood horses (5 of which had an intracardiac catheter in place) undergoing a standardised ...
Comparison of the cardiovascular effects of equipotent anesthetic doses of sevoflurane alone and sevoflurane plus an intravenous infusion of lidocaine in horses. To compare cardiovascular effects of sevoflurane alone and sevoflurane plus an IV infusion of lidocaine in horses. Animals-8 adult horses. Methods: Each horse was anesthetized twice via IV administration of xylazine, diazepam, and ketamine. During 1 anesthetic episode, anesthesia was maintained by administration of sevoflurane in oxygen at 1.0 and 1.5 times the minimum alveolar concentration (MAC). During the other episode, anesthesia was maintained at the same MAC multiples via a reduced concentration of sevoflurane plus an IV infusion of lidocaine. Heart rate, arterial blood pressures, blood...
Effects of intravenous administration of lidocaine on the minimum alveolar concentration of sevoflurane in horses. To determine effects of a continuous rate infusion of lidocaine on the minimum alveolar concentration (MAC) of sevoflurane in horses. Methods: 8 healthy adult horses. Methods: Horses were anesthetized via IV administration of xylazine, ketamine, and diazepam; anesthesia was maintained with sevoflurane in oxygen. Approximately 1 hour after induction, sevoflurane MAC determination was initiated via standard techniques. Following sevoflurane MAC determination, lidocaine was administered as a bolus (1.3 mg/kg, IV, over 15 minutes), followed by constant rate infusion at 50 μg/kg/min. Determination...
Effects of two training protocols on Angiotensin I-converting enzyme (ACE) activity in horses. Studies in man have shown a correlation between Angiotensin I-converting enzyme (ACE) genetic polymorphisms, ACE activity in the blood and superior athletic performance in sports requiring endurance. It has been hypothesised that the same correlation occurs in horses. There is no information in the literature concerning the effects of training on ACE activity in equine plasma. Objective: Exercise training influences the activity of circulating ACE and the response observed is dependent on the exercise protocol. Methods: Thirteen horses of mixed breeds were randomly allocated 2 different traini...
Endocrine dysregulation in critically ill foals and horses. Critical illness challenges many endocrine homeostatic systems to overcome diseases, stress, and hostile conditions that threaten survival. Coordinated and consecutive responses by the autonomic nervous system, endocrine metabolic adaptations to mobilize and conserve energy and electrolytes, cardiovascular adjustments to maintain organ perfusion, and immunomodulation to overcome infections and inflammation are required. Because most admissions to equine intensive care units are related to horses with gastrointestinal disease and septic foals, most endocrine information during critical disease ...
Equine metabolic syndrome. The concept of an equine metabolic syndrome (EMS) was first proposed in 2002. This concept has developed over time, and EMS was recently described in a consensus statement released by the American College of Veterinary Internal Medicine. In human medicine, metabolic syndrome (MetS) refers to a set of risk factors that predict the risk of cardiovascular disease, including obesity, glucose intolerance and insulin resistance (IR), dyslipidemia, microalbuminuria, and hypertension. EMS shares some of the features of MetS, including increased adiposity, hyperinsulinemia, IR, but differs in that lami...
