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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.
Cortisol release, heart rate and heart rate variability in the horse and its rider: different responses to training and performance. Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n=6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (P<0.001) but did not differ between performan...
Drugs for cardiovascular support in anesthetized horses. Despite the use of balanced anesthesia and fluids, drugs for cardiovascular support are often needed in anesthetized horses. Antimuscarinics can be used to treat bradycardia unrelated to hypertension. Vasopressors can be useful when hypotension is caused by vasodilation and/or when the effect of fluids and inotropes is insufficient. In most cases, however, inotropes, including sympathomimetics, calcium salts, and phosphodiesterase inhibitors, are preferred. Of the β-sympathomimetics, dobutamine remains the agent of choice. Calcium salts are mainly useful in hypocalcemic patients. Phosphodiest...
Plasma drug concentrations and clinical effects of a peripheral alpha-2-adrenoceptor antagonist, MK-467, in horses sedated with detomidine. To investigate plasma drug concentrations and the effect of MK-467 (L-659'066) on sedation, heart rate and gut motility in horses sedated with intravenous (IV) detomidine. Methods: Experimental randomized blinded crossover study. Methods: Six healthy horses. Methods: Detomidine (10 μg kg(-1) IV) was administered alone (DET) and in combination with MK-467 (250 μg kg(-1) IV; DET + MK). The level of sedation and intestinal sounds were scored. Heart rate (HR) and central venous pressure (CVP) were measured. Blood was collected to determine plasma drug concentrations. Repeated measures anova was ...
Anesthesia for the horse with colic. This article discusses anesthesia for horses with colic from acute gastrointestinal disease. Emphasis is placed on new developments in pre-, intra-, and immediate postoperative management over the last decade, including early goal-directed therapy (EGDT) in the resuscitation of septic patients, the controversy over the optimal fluid type to administer, and the management of complications, such as cardiovascular depression, hypoventilation and hypoxemia, and decreased colloid oncotic pressure (COP). An update on analgesia is also provided; older drugs such as ketamine and lidocaine are increasi...
Cardiac output monitoring in horses. Cardiac output (CO) is the volume of blood pumped out by the heart in 1 minute. Monitoring of CO can guide therapy and improve clinical outcome in critically ill patients and during anesthesia. Although there is increasing research into clinically useful methods of monitoring CO in equine patients, there are limitations to the available methods. There are 4 basic methods of measuring CO: (1) indicator methods, (2) a derivation of the Fick principle, (3) arterial pulse wave analysis, and (4) imaging diagnostic techniques. This article discusses the importance of CO, available technology, and ch...
Pharmacokinetics and pharmacodynamic effects of tolazoline following intravenous administration to horses. Tolazoline is an α2-adrenergic receptor antagonist, used in veterinary medicine to antagonize the central nervous system depressant and cardiovascular effects of α2 receptor agonists. The pharmacokinetics and pharmacodynamic effects of tolazoline when administered subsequent to detomidine in the horse were recently reported, although the reversal of the sedative and cardiovascular effects following detomidine may not be complete. The current study therefore investigated the pharmacokinetics and pharmacodynamic effects of tolazoline when administered as a sole agent. Nine healthy adult horses...
Reliability and identification of aortic valve prolapse in the horse. The objectives were to determine and assess the reliability of criteria for identification of aortic valve prolapse (AVP) using echocardiography in the horse. Results: Opinion of equine cardiologists indicated that a long-axis view of the aortic valve (AoV) was most commonly used for identification of AVP (46%; n=13). There was consensus that AVP could be mimicked by ultrasound probe malignment. This was confirmed in 7 healthy horses, where the appearance of AVP could be induced by malalignment. In a study of a further 8 healthy horses (5 with AVP) examined daily for 5 days, by two echocardiog...
Evaluation of tissue Doppler imaging for regional quantification of radial left ventricular wall motion in healthy horses. To compare the feasibility and repeatability of tissue Doppler imaging (TDI) for quantification of radial left ventricular (LV) velocity and deformation from different imaging planes and to correlate cardiac event timing data obtained by TDI to M-mode and pulsed-wave Doppler-derived time intervals in horses. Methods: 10 healthy adult horses. Methods: Repeated echocardiography was performed by 2 observers from right and left parasternal short-axis views at papillary muscle and chordal levels. The TDI measurements of systolic and diastolic velocity, strain rate, strain peak values, and timing we...
Use of continuous positive airway pressure (CPAP) to optimise oxygenation in anaesthetised horses–a clinical study. Hypoxaemia is a common problem during equine anaesthesia. Continuous positive airway pressure (CPAP) is a ventilation mode routinely employed in man to overcome hypoxaemia but has not been objectively assessed in horses. Objective: To test the effects of CPAP on oxygenation and its indices in anaesthetised horses in a clinical setting. Methods: Twenty-four healthy horses requiring anaesthesia in dorsal recumbency were anaesthetised using a standard protocol. Following orotracheal intubation and connection to an anaesthetic machine capable of applying CPAP, horses were randomly allocated to ven...
Use of physiologic and arterial blood gas variables to predict short-term survival in horses with large colon volvulus. To determine if preoperative physical examination and blood work values, intraoperative physiologic variables, and intraoperative treatments can be correlated with survival to anesthetic recovery and short-term survival to hospital discharge in horses that undergo exploratory celiotomy for large colon volvulus (LCV) with and without colon resection. Methods: Retrospective case series. Methods: Horses (n = 156) undergoing exploratory celiotomy for correction of LCV ≥ 360(ο) . Methods: Medical records (January 2000-December 2009) of horses that had surgical correction of LCV ≥ 360(ο) were ...
Traditional and quantitative assessment of acid-base and shock variables in horses with atypical myopathy. Descriptions of acid-base disturbances in atypical myopathy (AM) are limited. Objective: Describe and compare traditional and quantitative acid-base abnormalities and cardiovascular shock status in horses with AM at admission. Methods: 34 horses with AM, 15 healthy controls. Methods: Retrospective case-control study. Records were searched for shock variables (packed cell volume [PCV], blood urea nitrogen [BUN], heart and respiratory rate) and acid-base variables (venous blood gas analysis, electrolytes, total protein, lactate) on admission. Base excess (BE) of free water (BEfw), chloride (BEcl...
Influence of atrioventricular interaction on mitral valve closure and left ventricular isovolumic contraction measured by tissue Doppler imaging. The influence of atrioventricular (AV) interaction on mitral valve closure (MVC) and left ventricular (LV) isovolumic contraction is not fully clarified. We investigated the relationship among AV delay, MVC, and LV isovolumic contraction using a horse model because of the low heart rate and physiologically long AV delay. Results: Six horses were evaluated during sinus rhythm, right ventricular pacing without preceding atrial contraction, and dual-chamber pacing at AV delays of 150 to 350 ms, programmed at a constant rate. Right parasternal 4-chamber views were recorded for simultaneous measure...
Heart rate, heart rate variability and behaviour of horses during air transport. Heart rate (HR), HR variability (HRV) and behaviour score (BS) of nine horses were evaluated during an eight-hour air transport between The Netherlands and New York. HR and HRV parameters were calculated every five minutes during the air transport. Compared with transit (40±3), mean HRs were higher during loading into the jet stall (67±21, P<0.001), loading into the aircraft (47±6, P=0.011), taxiing (50±8, P=0.001), and during periods of in-flight turbulence (46±7, P=0.017). During the flight, individual horses showed differences in mean HR (P=0.005) and peak HR (P<0.001). By contra...
Cardiotoxicity, inflammation, and immune response after rattlesnake envenomation in the horse. Cardiac abnormalities are reported in rattlesnake-bitten horses. The prevalence and cause are unknown. Objective: To detect cardiac damage in rattlesnake-bitten horses by measuring cardiac troponin I (cTnI) and evaluating ECG recordings for presence of arrhythmias, and explore causes of this cardiac damage by measuring venom excretion, anti-venom antibodies, and tumor necrosis factor alpha (TNFα). Methods: A total of 20 adult horses with a clinical diagnosis of rattlesnake bite and 6 healthy adult horses. Methods: In a prospective clinical study, bite site swabs, blood samples, and urine samp...
[Prospective assessment of circulatory sufficiency of the patients after 3F equine pericardial stentless bioprosthesis replacement]. During years more and more advanced Technologies are used for treatment of severe aortic stenosis. One of them is equine pericardial stentless bioprothesis. Objective: the aim of the study was prospective assessment of circulatory sufficiency of the patients after 3F equine pericardial stentless bioprothesis replacement (ATS-Medtronic, Inc, Minneapolis, USA). Methods: Patients qualified to valve replacement were qualified to the study. The procedures were performed in general anesthesia and medial thoracothomy. The New York Heart Association (NYHA) scale was analyzed to estimate clinical resul...
Ventricular response during lungeing exercise in horses with lone atrial fibrillation. Atrial fibrillation (AF) is the most important dysrhythmia affecting performance in horses and has been associated with incoordination, collapse and sudden death. Limited information is available on ventricular response during exercise in horses with lone AF. Objective: To investigate ventricular response in horses with lone AF during a standardised lungeing exercise test. Methods: A modified base-apex electrocardiogram was recorded at rest and during a standardised lungeing exercise test from 43 horses diagnosed with lone AF. During the test horses walked for 7 min, trotted for 10 min, ca...
Anesthetic and cardiorespiratory effects of propofol, medetomidine, lidocaine and butorphanol total intravenous anesthesia in horses. Anesthetic and cardiorespiratory effects of medetomidine, lidocaine, butorphanol and propofol total intravenous anesthesia (MLBP-TIVA) were evaluated in horses undergoing an experimental surgery. Ten horses were premedicated with an intravenous injection (IV) of medetomidine (5 µg/kg) and butorphanol (20 µg/kg). Anesthesia was induced by administration of 1% propofol (3 mg/kg, IV) at a rate of 1 mg/kg/min (n=5, group-1) or 2% propofol administered at a rate of 6 mg/kg/min (n=5, group-2) following administration of lidocaine (1 mg/kg, IV) and then maintained by infusions of propofol, medetomi...
Effect of yohimbine on detomidine induced changes in behavior, cardiac and blood parameters in the horse. To describe selected pharmacodynamic effects of detomidine and yohimbine when administered alone and in sequence. Methods: Randomized crossover design. Methods: Nine healthy adult horses aged 9 ± 4 years and weighing 561 ± 56 kg. Methods: Three dose regimens were employed in the current study. 1) 0.03 mg kg(-1) detomidine IV, 2) 0.2 mg kg(-1) yohimbine IV and 3) 0.03 mg kg(-1) detomidine IV followed 15 minutes later by 0.2 mg kg(-1) yohimbine IV. Each horse received all three treatments with a minimum of 1 week between treatments. Blood samples were obtained and plasma analyzed for detomidin...
Early experience with continuous positive airway pressure (CPAP) in 5 horses — a case series. This case series is the first report of the use of CPAP (continuous positive airway pressure) ventilation in adult horses. Two horses and 3 ponies anesthetized for orthopedic procedures in lateral recumbency received 10 cm H(2)O CPAP. During anesthesia, arterial oxygen partial pressure tended to increase and arterial carbon dioxide pressure tended to increase despite increased minute ventilation index. The measured cardiovascular parameters were within physiologic limits. Cette série de cas est le premier rapport sur l’utilisation de la ventilation spontanée en pression positive continue ...
Alfaxalone and medetomidine intravenous infusion to maintain anaesthesia in colts undergoing field castration. The use of alfaxalone and medetomidine administered as an i.v. infusion to maintain anaesthesia has not previously been reported in the horse. Objective: To investigate the use of alfaxalone in hydroxpropyl-beta-cyclodextrin (Alfaxan) and medetomidine infusion as a field anaesthetic for short-term surgical procedures in the horse. Objective: Alfaxalone-medetomidine anaesthesia is suitable for short-term field anaesthesia in horses. Methods: Eleven healthy colts underwent 45 min of anaesthesia with an i.v. infusion of alfaxalone (2 mg/kg bwt/h) and medetomidine (5 μg/kg bwt/h) for routin...
Short-term incubation of equine laminar veins with cortisol and insulin alters contractility in vitro: possible implications for the pathogenesis of equine laminitis. This study investigated the effects of cortisol and insulin, hormones that affect both glycaemic status and vascular function, on the in vitro contractility of isolated healthy equine small laminar veins. Small veins (150-500 μm) draining the digital laminae from healthy horses or ponies were investigated by wire myography. Concentration response curves were constructed for noradrenaline (NA), phenylephrine (PE), endothelin-1 (ET-1) and 5-hydroxytryptamine (5-HT) in the presence of either cortisol (10(-6 ) m) or insulin (1000 μIU/mL). Cortisol significantly increased the maximum contractilit...
Efficacy of concurrent epidural administration of neostigmine and lidocaine for perineal analgesia in geldings. To evaluate perineal analgesic effects of 3 doses of neostigmine coadministered epidurally with lidocaine to geldings. Methods: 6 healthy geldings. Methods: A few days before each treatment, a catheter was inserted between the first and second coccygeal vertebrae via the caudal approach in each gelding; the catheter tip was threaded approximately 10 cm cranial into the midsacral region. Each horse received 4 epidural treatments: 2% lidocaine (0.2 mg/kg) alone and 3 doses of neostigmine (0.5, 1, or 2 μg/kg) coadministered with that same dose of lidocaine. Horses were restrained in stocks in a ...
Lithium dilution, pulse power analysis, and continuous thermodilution cardiac output measurements compared with bolus thermodilution in anaesthetized ponies. This study compares cardiac output (CO) measurements obtained by lithium dilution (LiDCO), pulse power analysis (PulseCO), and continuous thermodilution (CTD) with bolus thermodilution (BTD) in ponies. Methods: Eight isoflurane-anaesthetized Shetland ponies received xylazine, ketamine, and midazolam infusions (0.3, 1.2, and 0.018 mg kg(-1) h(-1), respectively). CO was measured with BTD, CTD, LiDCO, and PulseCO. Lithium was injected into the jugular vein and blood was sampled from the facial artery for lithium detection and this artery was also used for PulseCO. Measurements were obtained durin...
Effects of a constant-rate infusion of dexmedetomidine on the minimal alveolar concentration of sevoflurane in ponies. Dexmedetomidine has been administered in the equine as a constant-rate infusion (CRI) during inhalation anaesthesia, preserving optimal cardiopulmonary function with calm and coordinated recoveries. Inhalant anaesthetic sparing effects have been demonstrated in other species, but not in horses. Objective: To determine the effects of a CRI of dexmedetomidine on the minimal alveolar concentration (MAC) of sevoflurane in ponies. Methods: Six healthy adult ponies were involved in this prospective, randomised, crossover, blinded, experimental study. Each pony was anaesthetised twice (3 weeks washou...
Tissue Doppler imaging and 2-dimensional speckle tracking of left ventricular function in horses exposed to lasalocid. Tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2DST) can quantify left ventricular (LV) function in horses. Objective: To evaluate LV function by TDI and 2DST in horses with myocardial dysfunction after accidental ionophore intoxication. Methods: Sixty-seven horses exposed to lasalocid in feed. Methods: Prospective study. Horses were included in the study if a full cardiac examination was performed, consisting of determination of cardiac troponin I (cTnI), electrocardiography, and echocardiography. By TDI, radial systolic velocity and strain were measured. By 2DST, circumfere...
Effects on cardiopulmonary function and oxygen delivery of doses of romifidine and xylazine followed by constant rate infusions in standing horses. The objective of this study was to compare the cardiopulmonary effects of a xylazine or romifidine loading-dose, followed by a constant rate infusion (CRI) of the same α(2)-agonist. Nine research horses were treated in a randomized, blinded, crossover design with xylazine or romifidine. After instrumentation, a loading dose of intravenous xylazine (1mg/kg) or romifidine (80μg/kg) was administered, immediately followed by a CRI of xylazine (0.69mg/kg/h) or romifidine (30μg/kg/h) for a duration of 2h. Cardiopulmonary variables were recorded before bolus administration, during CRI, and for 1h ...
Serum cardiac troponin I concentrations in horses with cardiac disease. To measure the cardiac troponin I (cTnI) concentration in horses and determine whether it could be used in the diagnosis of myocardial disease, as well as determining the association between cTnI and survival. Methods: Prospective, observational study. Methods: Physical examination, echocardiography, telemetric electrocardiography and postmortem were used to diagnose cardiac disease. Diagnoses were grouped as myocardial disease, structural heart disease or lone arrhythmia. Blood samples were collected at admission for cTnI analysis and the results were compared with those for 18 healthy horses...
Resolution of sustained narrow complex ventricular tachycardia and tachycardia-induced cardiomyopathy in a Quarter Horse following quinidine therapy. Sustained narrow-QRS tachycardia of three months duration and left ventricular systolic dysfunction were identified in a fifteen-year-old Quarter Horse. No underlying cause for the tachyarrhythmia was found and no predisposing structural cardiac lesions were evident by echocardiography. Intravenous diltiazem and lidocaine were administered without achieving successful conversion of the arrhythmia. Oral quinidine therapy converted the tachyarrhythmia to sinus rhythm. Ventricular systolic dysfunction and chamber dilatation subsequently resolved. As with other species, echocardiographic features ...
Cardiac troponin I in racing standardbreds. Upper reference limits for cTnI have not been established for healthy Standardbred racehorses. Objective: To establish cTnI upper reference limits for Standardbred racehorses and determine if increases in plasma cTnI concentration can be detected in 1-2 hours after a race. Methods: Samples were obtained from 586 apparently healthy Standardbreds aged 2-14 years before racing and from the winners of 144 races 1-2 hours after the end of the race. Methods: Prospective, observational study; convenience sampling; assay validation; and reference limits determinations were performed according to ASCVP...
