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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.
Electroencephalographic and cardiovascular variables as nociceptive indicators in isoflurane-anaesthetized horses. To evaluate Fourier-transformed electroencephalographic (EEG) variables, mean arterial blood pressure (MAP) and pulse rate as nociceptive indicators in isoflurane-anaesthetized horses. Methods: Five standardbred and three Norwegian cold-blooded trotter stallions undergoing castration, aged 2-4 years, mass 378-538 kg. Methods: All horses received intravenous (IV) detomidine (10 microg kg(-1) IV) and butorphanol (0.01 mg kg(-1) IV). Additional detomidine (4 microg kg(-1) IV) was administered in the induction area. Anaesthesia was induced with ketamine (2.5 mg kg(-1) IV) and diazepam (40 microg k...
Anesthetic and cardiovascular effects of balanced anesthesia using constant rate infusion of midazolam-ketamine-medetomidine with inhalation of oxygen-sevoflurane (MKM-OS anesthesia) in horses. The anesthetic sparring and cardiovascular effects produced by midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.05 mg/ml (0.025 ml/kg/hr) drug infusion during sevoflurane in oxygen (MKM-OS) anesthesia was determined in healthy horses. The anesthetic sparring effects of MKM-OS were assessed in 6 healthy thoroughbred horses in which the right carotid artery was surgically relocated to a subcutaneous position. All horses were intubated and ventilated with oxygen using intermittent positive pressure ventilation (IPPV). The end-tidal concentration of sevoflurane (ET(SEV)) required to maintain s...
Changes in the heart rate and plasma epinephrine and norepinephrine concentrations of the stallion during copulation. The physiological indexes of the copulatory behavior of the stallion have not been investigated in detail and may differ from those of other species, such as humans and rats. In order to understand the breeding capability of various stallions, their behavior during copulation was observed, and heart rate (HR) and the plasma concentrations of norepinephrine (NA) and epinephrine (Ad) were measured sequentially for a total of 13 copulations carried out during 2 days. The mean HR at rest was 35.3 ± 0.9 beats per minute (b.p.m.) and it peaked during mounting (162.1 ± 5.4 b.p.m.). The HR a...
Early clinical experience with a new tubular equine pericardial stentless aortic valve. This study details a single-center experience with the 3F Therapeutics stentless aortic bioprosthesis(investigational device) and is part of a prospective,nonrandomized worldwide multicenter study. We assessed the implantation procedure and the valve's efficacy in terms of early mortality and morbidity and early echocardiographic valve performance. Methods: Between June 2001 and March 2004, 24 patients (14 men/10 women) underwent aortic valve replacement(AVR) with a 3F valve. Mean age was 72 +/- 13 years(range, 31-88 years). Combined revascularization was performed in 12 patients; 1 patient re...
[Precision-controlled echocardiographic left ventricular function parameters by repeated measurement on three consecutive days in trained and untrained warmblood horses]. Echocardiographic measurements have to be reliable and reproducible with only a low day to day variability for detecting pathological changes of left ventricular myocardial function in horses. The day dependent fluctuation margin represents an important indicator for the reproducibility of a method. To find out the day to day variability of echocardiographic parameter in healthy warmblood horses, in the present study repeated echocardiographic measurements at three consecutive days were carried out (at the same time and by the same examiner) at 11 untrained and 7 trained warmblood horses. The ...
Development of cardiovascular function in the horse fetus. In mammals, the mechanisms regulating an increase in fetal arterial blood pressure with advancing gestational age remain unidentified. In all species studied to date, the prepartum increase in fetal plasma cortisol has an important role in the maturation of physiological systems essential for neonatal survival. In the horse, the prepartum elevation in fetal cortisol and arterial blood pressure are delayed relative to other species. Hence, the mechanisms governing the ontogenic increase in arterial blood pressure in the horse fetus may mature much closer to term than in other fetal animals. In ...
Atropine reduces dobutamine-induced side effects in ponies undergoing a pharmacological stress protocol. High-dose dobutamine stress echocardiography has been shown to be cardiotoxic and arrhythmogenic in horses. However, the test may have benefit in practice as a pharmacological challenge of exercise without the treadmill being required. Objective: To investigate the effect of low-dose dobutamine on cardiac performance in ponies previously treated with atropine, in order to develop a pharmacological protocol that allows examination of the equine heart under stimulation. Methods: In 13 healthy Shetland ponies, heart rate (HR), stroke index (SI) and cardiac index (CI) were calculated from pulsed-w...
Intrapulmonary arteriovenous shunts of >15 microm in diameter probably do not contribute to arterial hypoxemia in maximally exercising Thoroughbred horses. The present study examined whether Thoroughbred horses performing strenuous exercise exhibit intrapulmonary arteriovenous shunting that may contribute to the observed arterial hypoxemia. Experiments were carried out on seven healthy, exercise-trained Thoroughbreds at rest, maximal exercise (galloping at 14 m/s on a 3.5% uphill grade for 120 s), and submaximal exertion (8 m/s on a 3.5% uphill grade for 150 s). Along with blood gas/hemodynamic parameters, intrapulmonary arteriovenous shunting was studied by injecting 15-microm-diameter microspheres, labeled with different stable isotopes, into t...
Effects of acepromazine on pulmonary gas exchange and circulation during sedation and dissociative anaesthesia in horses. To study pulmonary gas exchange and cardiovascular responses to sedation achieved with romifidine and butorphanol (RB) alone, or combined with acepromazine, and during subsequent tiletamine-zolazepam anaesthesia in horses. Methods: Six (four males and two females) healthy Standardbred trotters aged 3-12 years; mass 423-520 kg. Methods: Randomized, cross-over, experimental study. Methods: Horses were anaesthetized on two occasions (with a minimum interval of 1 week) with intravenous (IV) tiletamine-zolazepam (Z; 1.4 mg kg(-1)) after pre-anaesthetic medication with IV romifidine (R; 0.1 mg kg(-1...
Reliability of cardiorespiratory measurements with a new ergospirometer during intense treadmill exercise in Thoroughbred horses. This study investigated the reliability of measurements with a new equine ergospirometer (Quadflow). Heart rate and blood lactate responses during exercise in horses wearing the Quadflow and an open flow mask were also compared. The mean percentage error of the oxygen uptake measurements was 8.2% (range 2.1-12.5%). Percent error for peak expiratory flow rates ranged from 6.1% to 9.4 %, and for minute ventilation from 2.5% to 7.4%. The coefficients of variation of the means of four measurements in two horses exercising continuously at 9.0 m/s were <5% for variables related to pulmonary venti...
Total anomalous pulmonary venous connection in a foal. An 8-day-old Arabian-Morgan cross colt underwent cardiac evaluation. The foal was tachycardic, tachypneic, exercise intolerant and had a loud right-sided heart murmur and cyanotic mucous membranes. Total anomalous pulmonary venous connection was diagnosed with echocardiography and confirmed at postmortem examination. Total anomalous pulmonary venous connection is a very rare congenital cardiac abnormality that has not been reported before in the horse.
Cardiopulmonary effects and pharmacokinetics of i.v. dexmedetomidine in ponies. Currently available sedatives depress cardiopulmonary function considerably; therefore, it is important to search for new, less depressive sedatives. The study was performed to assess duration and intensity of cardiopulmonary side effects of a new sedative, dexmedetomidine (DEX), in horses. Objective: To study pharmacokinetics and cardiopulmonary effects of i.v. DEX. Methods: Pharmacokinetics of 3.5 microg/kg bwt i.v. DEX were studied in a group of 8 mature (mean age 4.4 years) and 6 old ponies (mean age 20 years). Cardiopulmonary data were recorded in mature ponies before and 5, 10, 20, 30, 4...
Sources and magnitude of variation of echocardiographic measurements in normal standardbred horses. The purpose of this study was to assess the intraobserver variation of various echocardiographic measures in standardbred trotters. Serial echocardiographic examinations were carried out on eight standardbred mares by one ultrasonographer for 5 separate days. During each examination, five nonconsecutive cardiac cycles (frames) were recorded and an average obtained for each individual measure. Various echocardiographic measures were obtained by use of two-dimensional (2-D), M-mode, color flow Doppler and pulsed wave Doppler echocardiography. The total variation in the echocardiographic measurem...
Cardiopulmonary effects of romifidine/ketamine or xylazine/ketamine when used for short duration anesthesia in the horse. The cardiovascular changes associated with anesthesia induced and maintained with romifidine/ketamine versus xylazine/ ketamine were compared using 6 horses in a cross over design. Anesthesia was induced and maintained with romifidine (100 microg/kg, IV)/ketamine (2.0 mg/kg, IV) and ketamine (0.1 mg/kg/min, IV), respectively, in horses assigned to the romifidine/ ketamine group. Horses assigned to the xylazine/ketamine group had anesthesia induced and maintained with xylazine (1.0 mg/kg, IV)/ketamine (2.0 mg/kg, IV) and a combination of xylazine (0.05 mg/kg/min, IV) and ketamine (0.1 mg/kg/min...
Effects of soy isoflavones and conjugated equine estrogens on inflammatory markers in atherosclerotic, ovariectomized monkeys. The effects of dietary soy isoflavones (IF) and conjugated equine estrogens (CEE) on circulating inflammatory markers were determined at the end of a 3-yr study of ovariectomized monkeys consuming a moderately atherogenic diet. Treatments were: 1) control, receiving alcohol-extracted soy-protein-based diet with low IF content (comparable to approximately 5 mg/d); 2) CEE, added to the control diet at a dose comparable to 0.625 mg/d; and 3) IF, consumed as a part of unextracted soy protein isolate at a dose comparable to 129 mg/d. Serum soluble vascular cell adhesion molecule-1 (sVCAM-1) was red...
Infection of immunodeficient horses with Sarcocystis neurona does not result in neurologic disease. Equine protozoal myeloencephalitis is a progressive neurologic disease of horses most commonly caused by infection with the apicomplexan parasite Sarcocystis neurona. Factors affecting neuroinvasion and neurovirulence have not been determined. We investigated the pathogenesis of infection with S. neurona in horses with severe combined immune deficiency (SCID). Two immunocompetent (IC) Arabian horses and two Arabian horses with SCID were infected orally with 5 x 10(5) sporocysts of S. neurona. Four IC horses and one SCID horse were infected intravenously (i.v.) with 5 x 10(8) merozoites of the ...
Pre-operative and anaesthesia-related risk factors for mortality in equine colic cases. Mortality rates for horses that have undergone emergency abdominal surgery are higher than for other procedures. Here, multivariable modelling of data from 774 surgical colic cases is used to identify pre-operative and anaesthesia-related variables associated with intra- and post-operative mortality. Intra-operative mortality was significantly (P<0.05), and positively associated with heart rate and packed cell volume (PCV) at admission, and negatively associated with the severity of pain. Post-operative mortality increased with increasing age and PCV at admission. Draught horses, Thoroughbr...
[Case report: aortic valve endocarditis in a horse]. A case of endocarditis of the aortic valve in a 11 year old thoroughbred is presented. Diagnostic approach, the value of echocardiography, and the various symptoms, complications and prognosis are discussed. The horse with ruptured aortic valves due to endocarditis with severe aortic and mitral regurgitation causing congestive heart failure, was euthanised due to bad prognosis.
Are so many adrenergic receptor subtypes really present in domestic animal tissues? A pharmacological perspective. Adrenergic receptors (ARs) are the cellular membrane binding sites through which natural catecholamines and sympathomimetic drugs exert their physiological and pharmacological effects. In recent decades, studies to clarify the distribution and function of ARs have been performed mostly on cultured cells, laboratory animals and human target tissues, but little is known about these aspects in domestic animals. This review focuses on AR structure, classification and signalling pathways and on AR subtype distribution in target tissues of some domestic animals, namely dogs, horses and bovines. In t...
Feeble weekly rhythmicity in hematological, cardiovascular, and thermal parameters in the horse. The homeostatic control of physiological processes is affected by a variety of temporal programs, such as circadian rhythms, estrous cycles, and circannual rhythms. The existence of circaseptan rhythms (endogenous rhythms with the duration of a week) has been postulated but not properly verified. In this study, we compared plasma concentration of lactic acid, systolic and diastolic blood pressure, and rectal temperature in athletic horses (maintained under a weekly training schedule) with those in sedentary horses (maintained under a constant schedule throughout the week). Although exercise ha...
The use of the standard exercise test to establish the clinical significance of mild echocardiographic changes in a Thoroughbred poor performer. A 4-year-old Thoroughbred gelding racehorse was referred to the Onderstepoort Veterinary Academic Hospital (OVAH) with a history of post-race distress and collapse. In the absence of any obvious abnormalities in the preceding diagnostic work-up, a standard exercise test was performed to determine an underlying cause for the post-race distress reported. In this particular case oxygen desaturation became evident at speeds as slow as 6 m/s, where PO2 was measured at 82.3 mm Hg. Similarly at a blood pH of 7.28, PCO2 had dropped to 30.0 mm Hg indicating a combined metabolic acidosis and respiratory...
Echocardiography and electrocardiography as means to evaluate potential performance in horses. Prediction of potential performance is one of the goals of exercise physiology investigations. When Selecting a horse for competition, one of the main objectives is to choose the one that predictably will reveal a competitive aptitude above the average. The horses used in this study underwent a two-dimensional echocardiography study and a conventional 3 leads electrocardiogram. The results show that heart score is not an appropriate index to evaluate the heart size in the horse. On the other hand, there are currently more suitable and accurate procedures such as echocardiography that allow per...
Effects of intravenous administration of dimethyl sulfoxide on cardiopulmonary and clinicopathologic variables in awake or halothane-anesthetized horses. To evaluate the cardiopulmonary and clinicopathologic effects of rapid IV administration of dimethyl sulfoxide (DMSO) in awake and halothane-anesthetized horses. Methods: Prospective study. Methods: 6 adult horses. Methods: Horses received IV infusion of 5 L of a balanced electrolyte solution with and without 1 g/kg (0.45 g/lb) of 10% DMSO solution when they were awake and anesthetized with halothane (4 treatments/horse). Arterial and venous blood samples were collected immediately before and at intervals during or after fluid administration and analyzed for blood gases and hematologic and ser...
The association between heart rate, heart rate variability, endocrine and behavioural pain measures in horses suffering from laminitis. The objective of this study was to compare the stress response of horses suffering from laminitis after short- and long-term treatment with the intent to evaluate power spectral analysis of heart rate variability (HRV) for pain monitoring. Data were collected from 19 horses with acute or chronic exacerbating laminitis without known primary disease before and after treatment with non-steroidal anti-inflammatory drugs (NSAID). Recordings were carried out the day after admission to the equine hospital. Measurements were repeated on day 7 of the treatment. The recorded parameters included a clinic...
In-vitro contraction of the equine aortic valve. The equine aortic valve is subject to non-inflammatory degenerative changes, associated with aortic valvular regurgitation (AR). This disease shares pathological and epidemiological features with AR in humans, and may serve as a useful model to study in-vitro functional responses associated with aging and disease. The study aim was to determine the contractile properties of the normal equine aortic valve. Methods: The contractile responses of equine aortic valves to angiotensin II, the thromboxane-mimetic U44069, endothelin-1, 5-hydroxytryptamine and the alpha-adrenoceptor agonists medetomidin...
Pulmonary artery wedge pressure measurement in healthy warmblood horses and in warmblood horses with mitral valve insufficiencies of various degrees during standardised treadmill exercise. In 12 healthy warmblood horses and 10 horses with mitral valve insufficiencies (MVI) of various degrees heart rate and pulmonary artery wedge pressure (PWP) was measured at rest and during standardised exercise on a high speed treadmill. There was a significant increase in PWP with each change in speed of the treadmill (p < 0.01). The PWP of horses with mild mitral valve regurgitation under working conditions was not significantly different compared to the healthy horses. The horses with moderate mitral valve regurgitation showed a significant higher pulmonary artery wedge pressure at rest ...
Comparison of systolic cardiac function before and after treatment of atrial fibrillation in horses with and without additional cardiac valve insufficiencies. Clinical, electrocardiographic and echocardiographic examinations were conducted before therapy and 4 days after conversion to normal sinus rhythm in 15 horses with a history of atrial fibrillation of 2-6 months duration. Seven horses showed no other signs of cardiac disease. Four horses suffered additionally from mitral valve insufficiency, while six horses had aortic valve insufficiency, including two of the four horses with mitral valve insufficiency, but none had signs of congestive heart failure. Doppler echocardiographic estimates of various variables were made for assessment of systolic...
Phenytoin sodium as a treatment for ventricular dysrhythmia in horses. Five adult horses with ventricular extra systoles (VES) and 2 with ventricular tachycardia (VT) refractory to treatment with rest, anti-inflammatory drugs, lidocaine, or procainamide were treated with phenytoin sodium p.o. q12h. The starting dosage of phenytoin was 20 or 22 mg/kg body weight (BW) q12h, and the maintenance dosage varied from 8 to 17 mg/kg BW q12h. The mean +/- standard deviation therapeutic blood concentration of total phenytoin was 8.8 +/- 2.1 mg/L, and the mean concentration of free phenytoin of 2.5 +/- 0.5 mg/L was relatively constant at a range of 24 to 29% of the total phe...
In vitro and in vivo studies of homocysteine in equine tissues: implications for the pathophysiology of laminitis. Elevated plasma homocysteine (HCy) concentration is a risk factor for cardiovascular diseases associated with endothelial dysfunction, including the human digital ischaemic disease, Raynaud's phenomenon. Objective: HCy causes dysfunction of equine vascular endothelium and elevated plasma concentrations predispose to laminitis. Objective: To determine 1) the concentration of HCy in vitro, which inhibits equine vascular endothelial cell function and 2) any association between risk of laminitis and plasma HCy concentration. Methods: Endothelial function was studied by measuring endothelium-depend...
