Hemodynamics in horses refers to the study of blood flow and the forces involved in circulation within the equine cardiovascular system. It encompasses the examination of heart function, blood pressure, and the distribution of blood to various tissues and organs. Key parameters in equine hemodynamics include cardiac output, vascular resistance, and blood volume. These factors are integral to understanding how horses respond to exercise, stress, and various health conditions. This page aggregates peer-reviewed research studies and scholarly articles that explore the mechanisms, measurement techniques, and clinical implications of hemodynamic processes in equine physiology and veterinary medicine.
HOLT JP, RHODE EA, PEOPLES SA, KINES H.Studies of left ventricular volume and pressure have been carried out in the control state in four classes of intact anesthetized mammals (horses, cattle, swine, and dogs), body weights of which varied 54-fold. On the basis of these studies of both large and small hearts, extending over a wide range, a pattern of function for the left ventricle of all mammals has been described. Mathematical equations are given describing the interrelationships between left ventricular end-diastolic volume and end-systolic volume, stroke volume, cardiac output, stroke-work, heart rate, and total peripheral res...
Wijnberg ID, van der Kolk JH.Atrial fibrillation is a disorder of cardiac rhythmicity, and its importance in the horse depends on the underlying cause and the function of the horse. Before the decision is taken to start treatment, it has first to be ascertained whether treatment is worthwhile and whether the horse is an appropriate candidate for treatment. This article gives a short overview of current opinion on the cause and treatment of atrial fibrillation in the horse. The most used treatment at the moment, oral chinidine sulphate, is discussed. The hemodynamic consequences of atrial fibrillation and the response of a...
Vitums A, Grant BD, Stone EC, Spencer GR.ABSTRACT Transposition of the aorta to the right ventricle with atresia of the pulmonary trunk was described in a 2 year old horse. Clinical and physiological examinations were performed and data recorded. Teratogenesis of the present anomaly was discussed and the literature reviewed. The probable course of circulation during the fetal life and after birth of this animal was suggested. An extensive col-lateral circulation was developed to the lungs, which might explain how the animal could live so long.
Chompoosan C, Pongthaisong P, Kenchaiwong W, Pontaema T, Lerdweeraphon W.Pregnancy affects maternal hemodynamics. The changes in autonomic nervous system activity for hemodynamics adaptation in pregnant horses are still unclear. Thus, this study aimed to examine the effect of pregnancy on electrocardiographic, vasovagal tonus index, and echocardiographic variables in horses. Unassigned: A total of 23 Thai native crossbred mares without any cardiac abnormalities were included in this study. The animals were assigned into two groups, a non-pregnant mare group (n =12) and a pregnant mare group (n = 11). Electrocardiogram recordings (paper speed = 25 mm/s and calibrati...
Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM.Mares are the only companion animals simulating women in the large diameter of their follicles. Horses start reproduction at the age of three years, and some of them live for >30 years, so aging influences their reproductive capacity. Mares are sensitive to summer heat stress as they can sweat like humans. Unassigned: The current work aimed to study the effects of age (young versus senile), season (cold versus hot), and the hormonal treatments during embryo collection on the dominant and subordinate follicular dynamics and hemodynamics and circulating ovarian hormones in embryo donor mares ...
Dos Santos Rosse N, Reis ECC.The resistivity index (RI) evaluates haemodynamic based on arterial resistance. Alterations in renal blood flow are important for the early detection of kidney damage, as perfusion might be one of the first affected aspects. Objective: To retrieve published studies on equine renal RI to develop a standardised method of renal ultrasonographic examination and to evaluate the current reference range for the renal RI in horses. Methods: Systematic review. Methods: An electronic search in Science Direct, PubMed, Scopus and Web of Science databases was performed in February 2023 using the terms 'RI'...
Dupont J, Roman Dura B, Salciccia A, Serteyn D, Sandersen C.To study the changes in dynamic compliance (C), ventilation/perfusion (V˙/ Q˙) mismatch and haemodynamic variables in hypoxaemic anaesthetized horses whose PaO increased following salbutamol inhalation. Methods: Retrospective, clinical, cohort study. Methods: A group of 73 client-owned horses treated with salbutamol when PaO <100 mmHg (13.3 kPa) during anaesthesia. Methods: Horses were divided into two groups: responders (R), where PaO after salbutamol ≥1.2 PaO before treatment (i.e. ≥20% increase), and non-responders (NR), where PaO after salbutamol <1.2 PaO before treatment. Demographi...
Long AE, Hurcombe S, Hopster K.To compare the ability of bioreactance noninvasive cardiac output (BR-NICO) with thermodilution cardiac output (TDCO) for the measurement of cardiac output (CO) in healthy adult horses receiving 2 different IV volume replacement solutions. Methods: Prospective randomized crossover study from September to November 2021. Methods: University teaching hospital. Methods: Six university-owned adult horses. Methods: Horses were randomly assigned to receive 7.2% hypertonic saline solution (HSS) or 6% hydroxyethyl starch (130/0.4) solution (HETA). BR-NICO and TDCO were measured simultaneously at baseli...
Brito PHS, Ferreira MA, Rusch E, Arantes JA, Carregaro AB, Valadão CAA, Ghantous GF, Dória RGS.Submitting late-term pregnant mares to anesthesia for non-obstetric surgery raises concerns about the survival of the mother and fetus. This study aimed to evaluate and describe transient maternal and fetal hemodynamic changes during general inhalation anesthesia in mares during the last month of gestation. Nine adult mares in the last month of gestation were subjected to general inhalation anesthesia and dorsal recumbency for 90 minutes. Trans-anesthetic vital parameters, arterial hemogasometry, cardiac output, pulmonary arterial pressure, central venous pressure, and fetal heart rates were a...
Mendoza FJ, Buzon-Cuevas A, Aguilera-Aguilera R, Gonzalez-De Cara CA, De Las Heras A, Perez-Ecija A.Systemic inflammatory response syndrome (SIRS) in donkeys is observed to be secondary to colic, diarrhea or pleuropneumonia, among other disorders. Horses with SIRS develop secondary disturbances such as hyperlipemia, laminitis, disseminated intravascular coagulopathy, and hemodynamic and cardiac derangements, which impair their prognosis and increase the mortality rate. In donkeys, no information is available on the effect of experimentally induced endotoxemia in the cardiovascular system. Acute experimental endotoxemia was induced by lipopolysaccharide (LPS) infusion in six healthy adult non...
Sauter PK, Steblaj B, Kästner SBR, Söbbeler FJ, Reiners JK, Kutter APN, Bautitsta AJG, Neudeck S.Microcirculation is the essential link between macrocirculation and cellular metabolism. Objective: To test our hypotheses that microcirculation variables will show a heterogeneous flow pattern during experimental endotoxaemia, and that fluid therapy and noradrenaline (NA) infusion will normalise altered microcirculation variables. Methods: In vivo experiments. Methods: Six healthy adult horses were anaesthetised with dexmedetomidine, ketamine, and diazepam and were mechanically ventilated under isoflurane anaesthesia. Endotoxaemia was induced with 30 ng kg Escherichia coli lipopolysacchar...
Gorenberg EB, Slack J, Stefanovski D, Theiss D, Hopster K.Dobutamine is a first-line therapy for hypotension in anaesthetised horses, but the effects on haemodynamic parameters in standing and anaesthetised horses are not well studied. Objective: To investigate the effects of dobutamine in escalating dosages on haemodynamic performance in awake and anaesthetised horses. Methods: Randomised cross-over experimental study. Methods: Six healthy adult horses were enrolled, including both standing and isoflurane-anaesthetised experiments with 1-week washout. Heart rate, mean arterial pressure (MAP), central venous pressure, pulmonary arterial pressure, and...
Oyaneder L, Lagos N, Dörner C.The present study was conducted to evaluate the safety and the long-lasting anesthetic properties of Neosaxitoxin (NeoSTX) when injected into the intercoccygeal space in standing horses. A group of eighteen (n = 18) healthy client-owned mature crossbreed horses were enrolled in this study. Caudal epidural injection was ascertained by two methods, the "hanging drop" technique and radiographs. Horses were allocated into three groups (n = 6) each group receiving different dosages of NeoSTX. To assess the onset of action and duration of anesthesia, six horses received 20 μg in 2 mL, six 20Â...
Kazama T, Hector RC, Hess AM, Rezende ML.To determine the cardiopulmonary effects of oral trazodone before isoflurane anesthesia in systemically healthy horses. Unassigned: 12 horses donated for euthanasia (from August 2022 through June 2023) due to conditions unrelated to the cardiovascular system were included in this prospective, randomized, controlled trial. Horses were assigned to receive oral trazodone (6 mg/kg; n = 7) or corn syrup (n = 5) 1 hour before xylazine (1 mg/kg, IV) sedation, ketamine (2.2 mg/kg, IV) and propofol (0.7 mg/kg, IV) induction, and anesthetic maintenance with inhaled isoflurane (target 1.6% expired) for 7...
Muir WW, Yiew XT, Bateman SW, Hahn RG.Fluid therapy in horses is primarily empirical. Evidence-based quantification of the disposition of intravenous (IV) crystalloids used in clinical practice could enhance the effectiveness of fluid therapy. Objective: To determine the pharmacokinetics (i.e., volume kinetics: VK) and associated haemodynamic effects of IV lactated Ringer's solution (LRS) in adult euvolemic horses. Methods: Unmasked multiple subjects, single baseline design. Methods: Thirteen healthy, euvolemic adult female horses were administered an IV bolus of LRS and monitored over 4 h. Haemoglobin, albumin and haematocrit c...
Garcia LL, Vicentini YF, Nagashima JK, de Souza AF, Pereira MAA, da Silva LCLC, Fantoni DT.To assess the sublingual microcirculation in horses anesthetized with isoflurane and undergoing constant rate infusion of dexmedetomidine (DEX) and lidocaine (LID). Unassigned: 16 horses undergoing arthroscopy were included in a blind, randomized study comparing 2 groups: a DEX group (DEX-LID; 1.75 μg·kg-1·h-1 with a LID bolus of 1.3 mg·kg-1 followed by a continuous infusion of 0.05 mg·kg-1·min-1) and a LID-only group (LID; at the same dose). Hemodynamic variables, including mean, systolic, and diastolic blood pressure; heart rate; capnography; blood gas analysis; blood lactate; and orth...
Weixler VHM, Aldana-Aguirre J, Zaulan O, Chin V, Guerguerian AM, Mertens L, Honjo O.We present 2 cases of traumatic ventricular septal defects (VSDs), both caused by horse kick injuries. Given this rare but critical condition, we decided to share our experiences and the lessons learned managing these cases. Methods: The first patient, a 12-year-old girl, was trampled by a horse, sustained a traumatic apical ventricular septal defect with pseudoaneurysm, was stabilized first, and underwent surgical closure 19 days after the injury. The second patient, a 9-year-old girl, was kicked by a horse in the chest; developed profound cardiogenic shock; and was found to have multiple lar...
