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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.
[Pulmonary artery wedge pressure and heart rate measurement during pharmacological stress induction for left cardial function diagnosis in horses with and without heart disease]. In 18 horses, the pulmonary artery wedge pressure and the heart rate were measured during pharmacological stress load. 12 horses were healthy (4 trained, 8 untrained) and 6 horses had a heart disease (3 trained, 3 untrained). Pharmacological stress induction was carried out with the sympathomimetic drug dobutamine at a dosage rate of 7.5 microg/kg/min over 10 minutes of infusion. At the fourth minute, the parasympatholytic drug atropine was administered (5 microg/kg bw), and the heart rate and the pulmonary artery wedge pressure were continuously measured over 26 minutes. During sole dobutamin...
Septicemia and cardiovascular infections in horses. This article first reviews cardiovascular infections, including endocarditis, myocarditis, vasculitis, and pericarditis. It then addresses what is known at this stage about the effects of sepsis on the cardiovascular system. Some information is provided from current human literature to familiarize the reader with the diagnostics and therapeutics that may eventually be used in equine practice as well.
Comparison of 2 endothelin-receptor antagonists on in vitro responses of equine palmar digital arterial and venous rings to endothelin-1. The goals of this study were to determine the concentration-response (C-R) relationship of endothelin-1 (ET-1), compare 2 ET-receptor antagonists and determine the antagonist concentrations that block the vasomotor effects of ET-1, and compare the effectiveness of ET-1 and previously studied vasoconstrictors in equine palmar digital arterial and venous rings in vitro. Vessel rings from 8 nonlaminitic horses were placed in Tyrode's solution, 1 side fixed to the floor of an organ bath and the other side fixed to a force-displacement transducer. Two separate studies were conducted: (I) incubation...
Cardiac arrhythmias associated with piroplasmosis in the horse: a case report. Cardiac dysfunction is a rare complication of babesiosis in domestic animals. The horse in this report showed clinical signs of anorexia, depression, fever, icterus and brown urine, and laboratory results (monocytosis, thrombocytopenia, azotemia, hyperbilirubinemia and bilirubinuria) indicated sub-acute piroplasmosis. Furthermore, junctional and polymorphic ventricular premature complexes and tachycardia associated with increased serum cardiac troponin I and myocardial-bound creatine kinase concentration were found. The diagnosis of piroplasmosis was confirmed by serology. Specific and support...
Analgesic effects of subarachnoidally administered hyperbaric opioids in horses. To evaluate the effects of subarachnoidally administered hyperbaric morphine, buprenorphine, and methadone on avoidance threshold to noxious electrical stimulation of the perineal, sacral, lumbar, and thoracic regions in horses. Methods: 6 healthy adult horses. Methods: Horses were assigned to receive subarachnoid administration of hyperbaric morphine (0.01 mg/kg), buprenorphine (0.001 mg/kg), methadone (0.01 mg/kg), or 10% dextrose solution in equal volumes (5 mL). Electrical stimulation was applied every 10 minutes for 60 minutes and every 30 minutes for 120 minutes after subarachnoid inject...
Effect of atropine-dobutamine stress test on left ventricular echocardiographic parameters in untrained warmblood horses. The aim of this study was to investigate the effect of combined atropine low-dose dobutamine stress test on left ventricular parameters in adult warmblood horses, to establish a potential protocol for pharmacological stress echocardiography. Seven healthy untrained warmblood horses aged 9 to 22 years were used. Heart rate (HR) and left ventricular B- and M-mode dimensions were recorded at baseline and during stress testing with 35 microg/kg atropine IV followed by incremental dobutamine infusion of 2 to 6 microg/kg/min. HR increased significantly (P < .05) during the pharmacological challen...
Stress echocardiography in warmblood horses: comparison of dobutamine/atropine with treadmill exercise as cardiac stressors. The purpose of this study was to determine whether the combination of dobutamine and atropine causes cardiac stress equivalent to treadmill exercise. Therefore, electrocardiography and echocardiography were performed on 10 warmblood horses before, during, and after different cardiac stress tests. Stressors consisted of a standardized treadmill exercise and combined administration of dobutamine (7.5 microg/kg/min) and atropine (5 microg/kg). Maxima heart rates were achieved during the treadmill exercise (175 +/- 10 bpm). After exercise, a rapid decrease in heart rate was observed. Subsequently,...
Dissociative anaesthesia during field and hospital conditions for castration of colts. The principal aim of this study was to evaluate dissociative anaesthesia for castration of colts during field conditions. Three dissociative anaesthetic protocols were evaluated during castration of colts in an animal hospital. The protocol considered to be the most suitable was thereafter evaluated during castration of colts under field conditions. Respiratory and haemodynamic parameters and the response to surgery were determined during anaesthesia. All horses breathed air spontaneously during anaesthesia. Under hospital conditions 26 colts were randomised to receive one of three anaesthetic...
Hyperhydration prior to a simulated second day of the 3-day moderate intensity equestrian competition does not cause arterial hypoxemia in Thoroughbred horses. Dehydration and the associated impairment of cardiovascular and thermoregulatory function comprise major veterinary problems in horses performing prolonged exercise, particularly under hot and humid conditions. For these reasons, there is considerable interest in using pre-exercise hyperhydration to help maintain blood volume in the face of the excessive fluid loss associated with sweat production during prolonged exertion. However, recently it was reported that pre-exercise hyperhydration causes arterial hypoxemia in horses performing moderate intensity exercise simulating the second day of a...
Morphine administration in horses anaesthetized for upper respiratory tract surgery. To determine the effect of morphine administration on commonly monitored cardio-respiratory variables and recovery quality in horses undergoing anaesthesia and surgery. Methods: Prospective, randomized clinical study. Methods: Thirty-eight thoroughbred horses, 32 geldings and six mares, 3-13 years old, weighing 411-600 kg. Methods: A standard anaesthetic technique was used. Twenty minutes after induction of anaesthesia horses received 0.1 mg kg(-1) (0.1 m) or 0.2 mg kg(-1) (0.2 m) morphine by intravenous injection. A control group did not receive morphine. Heart rate, respiratory rate (fr), me...
Evaluation of total intravenous anesthesia with propofol or ketamine-medetomidine-propofol combination in horses. Objective-To compare the anesthetic and cardiorespiratory effects of total IV anesthesia with propofol (P-TIVA) or a ketamine-medetomidine-propofol combination (KMP-TIVA) in horses. Design-Randomized experimental trial. Animals-12 horses. Procedure-Horses received medetomidine (0.005 mg/kg [0.002 mg/lb], IV). Anesthesia was induced with midazolam (0.04 mg/kg [0.018 mg/lb], IV) and ketamine (2.5 mg/kg [1.14 mg/lb], IV). All horses received a loading dose of propofol (0.5 mg/kg [0.23 mg/lb], IV), and 6 horses underwent P-TIVA (propofol infusion). Six horses underwent KMP-TIVA (ketamine [1 mg/kg/...
Degenerative suspensory ligament desmitis as a systemic disorder characterized by proteoglycan accumulation. Degenerative suspensory ligament desmitis (DSLD) is a debilitating disorder thought to be limited to suspensory ligaments of Peruvian Pasos, Peruvian Paso crosses, Arabians, American Saddlebreds, American Quarter Horses, Thoroughbreds, and some European breeds. It frequently leads to persistent, incurable lameness and need to euthanize affected horses. The pathogenesis remains unclear, though the disease appears to run in families. Treatment and prevention are empirical and supportive, and not effective in halting the progression of the disease. Presently, the presumptive diagnosis of DSLD is ...
Thermographic study of in vivo modulation of vascular responses to phenylephrine and endothelin-1 by dexamethasone in the horse. In vitro, glucocorticoids potentiate vasoconstriction of equine digital vessels to catecholamines and this has been implicated as a mechanism of glucocorticoid-induced laminitis. This observation has never been confirmed in vivo. Objective: To study the effects of glucocorticoid therapy on vasoconstrictor responsiveness in the horse in vivo. Methods: In a blinded, randomised cross-over experiment, 9 horses were treated with either dexamethasone (0.1 mg/kg bwt i.v. q. 24 h) or saline i.v. for 6 days. The changes in local average skin temperature before (baseline) and after intradermal injection...
Changes in heart rate and heart rate variability in Thoroughbreds during prolonged road transportation. To determine whether evaluation of heart rate (HR) and HR variability (HRV) during prolonged road transportation in horses provides a sensitive index of autonomic stimulation. Methods: Five 2-year-old Thoroughbreds. Methods: ECGs were recorded as horses were transported for 21 hours in a 9-horse van. Heart rate, high-frequency (HF) power, low-frequency (LF) power, and LF-to-HF ratio from Fourier spectral analyses of ECGs were calculated and compared with values recorded during a 24-hour period of stall rest preceding transportation. Results: HR, HF power, and LF power had diurnal rhythms durin...
Effect of intratesticular injection of lidocaine on cardiovascular responses to castration in isoflurane-anesthetized stallions. To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions. Methods: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration. Methods: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). Af...
Development of baroreflex function and hind limb vascular reactivity in the horse fetus. This study investigated, in vivo, the mechanisms underlying the development of cardiovascular function in the horse fetus, with particular relevance to baroreflex function and hind limb vascular arterial reactivity to constrictor agonists. Under general anaesthesia, vascular catheters were inserted and a Transonic flow probe was implanted around one of the metatarsal arteries of 13 horse fetuses, either at 0.6 of gestation (n= 6) or at 0.9 of gestation (n= 7, term approximately 335 days). At least 5 days after surgery, pressor, vasoconstrictor and cardiac chronotropic responses to exogenous bo...
Percutaneous aortic valve implantation retrograde from the femoral artery. Percutaneous aortic valve implantation by an antegrade transvenous approach has been described but is problematic. Retrograde prosthetic aortic valve implantation via the femoral artery has potential advantages. Percutaneous prosthetic aortic valve implantation via the femoral arterial approach is described and the initial experience reported. Results: The valve prosthesis is constructed from a stainless steel stent with an attached trileaflet equine pericardial valve and a fabric cuff. After routine aortic balloon valvuloplasty, a 22F or 24F sheath is advanced from the femoral artery to the a...
Echocardiographic evidence of an aortico-pulmonary septal defect in a 4-day-old thoroughbred foal. We describe the echocardiographic findings in a 4-day-old thoroughbred foal with an aortico-pulmonary septal defect. The foal had labored breathing, cyanotic mucous membranes and a continuous grade 5/6 heart murmur with point of maximal intensity over the base of the heart on the right side. Echocardiographically, there was a large communication between the aorta and the pulmonary artery just dorsal to the base of the heart. The cardiac anomaly seen during the echocardiographic exam was confirmed at necropsy where a large communication between the two great vessels was observed. These findings...
Effects of an alveolar recruitment maneuver on cardiovascular and respiratory parameters during total intravenous anesthesia in ponies. To evaluate pulmonary and cardiovascular effects of a recruitment maneuver (RM) combined with positive end-expiratory pressure (PEEP) during total intravenous anesthesia in ponies. Methods: 6 healthy adult Shetland ponies. Methods: After premedication with detomidine (10 microg/kg, IV), anesthesia was induced with climazolam (0.06 mg/kg, IV) and ketamine (2.2 mg/kg, IV) and maintained with a constant rate infusion of detomidine (0.024 mg/kg/h), climazolam (0.036 mg/kg/h), and ketamine (2.4 mg/kg/h). The RM was preceded by an incremental PEEP titration and followed by a decremental PEEP titrati...
Primary cardiac angiosarcoma resection combined with right coronary artery bypass grafting. A 41-year-old woman presented with symptoms of cardiac tamponade. Diagnosis of a primary malignant tumor in the right atrium without distant metastasis was made by echocardiography, computed tomography and coronary angiography. Aggressive surgery consisting of resection of the tumor including the right atrial wall together with the right coronary artery and sinus node was performed. This was followed by coronary artery bypass grafting with myocardial electrode implantation for reconstruction of the right atrial wall using an equine pericardium. Final diagnosis was of angiosarcoma by pathologic...
Correlation between 25 element contents in mane hair in riding horses and atrioventricular block. The influence of atrioventricular block (AV-block) on the trace elemental status in a horse hair was studied. The particle-induced X-ray emission (PIXE) method has provided a reliable, rapid, easy, and relatively inexpensive diagnostic method. Twenty-five elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Hg, K, Mg, Mn, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Sr, Ti, Y, and Zn) in mane hair and serum were measured by the PIXE method. A horse hair with first- and second-degree AV-block contained significantly greater amounts of Br, Ca, Sr, and Zn than those of horses without electrocardiographic abnormalities...
Effect of exercise intensity and repetition on heart rate variability during training in elite trotting horse. RR intervals of ten elite trotting horses were recorded during an interval training session performed on track. This study examined two hypotheses. Firstly, like in humans, the hyperpnea combined with a decrease in cardiac autonomic control on heart rate during heavy exercise could result in a prevalence of high frequency heart rate variability. Secondly, this prevalence could increase with the heavy exercise repetition. Two exercise intensities were compared: moderate (ME) and heavy (HE). Furthermore, heavy exercise repetitions were compared between the beginning and the end of the interval t...
Use of color Doppler echocardiography to assess the development of valvular regurgitation in Standardbred trotters. To evaluate the incidence and development of valvular regurgitation and its effect on racing performance in Standardbred trotters from 2 to 3.5 years of age. Methods: Longitudinal observational study. Methods: 103 horses. Methods: Horses were examined via echocardiographic imaging 4 times at 6-month intervals. Two-dimensional and M-mode echocardiographic examinations were performed in each horse, and color Doppler imaging was used to detect and evaluate regurgitant blood flow at each valve. Results: For all cardiac valves, the frequency of valvular regurgitation increased significantly during ...
Pulmonary artery wedge pressure during treadmill exercise in warmblood horses with atrial fibrillation. The heart rate and the pulmonary artery wedge pressure (PWP) was measured in 10 healthy warmblood horses and in six warmblood horses with atrial fibrillation (AF) at rest and during standardised treadmill exercise. During treadmill exercise, the increase in heart rate was significantly higher in the horses with AF than in the healthy horses. Horses with AF showed a significantly higher increase in PWP at treadmill velocities of 5m/s and faster, than did the healthy horses. The differences in PWP between both groups increased with treadmill strain. The present study demonstrates that there is a...
Cardiopulmonary effects of desflurane in horses. To determine the cardiopulmonary effects of desflurane (DES) in horses. Methods: Six healthy adult horses, three males and three females, aged 9 +/- 4 (mean +/- SD) years and weighing 370 +/- 36 kg. Methods: Anaesthesia was induced with an O2 (10 L minute(-1)) and DES mixture (vaporizer setting 18%). After oro-tracheal intubation, horses were positioned in right lateral recumbency. Anaesthesia was maintained with DES in O2 (20 mL kg(-1) minute(-1)) delivered through a large animal circle breathing system. The minimum alveolar concentration of DES (MAC(DES)) that prevented purposeful movement i...
Total intravenous anaesthesia in horses using medetomidine and propofol. To examine the clinical suitability of medetomidine-propofol infusions for total intravenous anaesthesia in horses. Methods: Fifty client-owned horses of mixed breed, age [mean +/- SD (range)] 6.6 +/- 4.4 (0.04-18) years, mass 478 +/- 168.3 (80-700) kg presented for a range of operations requiring general anaesthesia. Methods: Pre-anaesthetic medication was intravenous (IV) medetomidine 7 mug kg(-1). Anaesthesia was induced with IV ketamine (2 mg kg(-1)) and diazepam (0.02 mg kg(-1)). After endotracheal intubation, O2 was delivered (FiO2 > 0.85). Positive pressure ventilation was initiated ...
