Heart rate in horses is a physiological parameter that reflects the number of heartbeats per minute. It is an important indicator of cardiovascular function and can be influenced by factors such as exercise, stress, excitement, and health status. Monitoring heart rate provides valuable insights into the horse's physical condition and can aid in assessing fitness levels or detecting potential health issues. In equine practice, heart rate is often measured using stethoscopes, heart rate monitors, or electrocardiograms. This page compiles peer-reviewed research studies and scholarly articles that explore the determinants, measurement techniques, and implications of heart rate variations in equine health and performance.
Hollis AR, Ousey JC, Palmer L, Stephen JO, Stoneham SJ, Boston RC, Corley KT.Norepinephrine increases arterial blood pressure but may have adverse effects on renal blood flow. Fenoldopam, a dopamine-1 receptor agonist, increases urine output in normotensive foals. The combination of norepinephrine and fenoldopam may lead to improved renal perfusion compared with an infusion of norepinephrine alone. The combined effects of these drugs have not been reported in the horse. Objective: Norepinephrine will alter the hemodynamic profile of foals without affecting renal function. Addition of fenoldopam will change the renal profile during the infusions without changing the hem...
Zucca E, Ferrucci F, Croci C, Di Fabio V, Zaninelli M, Ferro E.The aim of this study was to obtain echocardiographic measurements and establish reference ranges for 14 parameters in Standardbred racehorses in training. Background: Several studies have been published about cardiac measurements in Thoroughbreds, Standardbreds, National Hunt horses, Warmbloods and ponies; however, not all parameters have been published for the Standardbred trotter in training. Methods: Thirty normal Standardbred racehorses in training were assessed by two-dimensional echocardiography (2-D) and M-mode echocardiography using standardized imaging planes. Mean values, standard d...
Neuhauser S, Palm F, Ambuehl F, Aurich C.In this study, effects of altrenogest treatment (0.088 mg/kg daily) given to mares during late gestation until parturition on the time and the process of foaling, neonatal adaptation and postnatal development were analysed. The number of animals was 6 in the treatment group and 7 in the control group. Gestational length tended to be shorter in mares given altrenogest. Birth weight of the foals and weight of the placenta did not differ between groups. The second stage of parturition was prolonged in the altrenogest-treated mares (p<0.05). Foals born to altrenogest-treated mares had a significan...
Peterbauer C, Larenza PM, Knobloch M, Theurillat R, Thormann W, Mevissen M, Spadavecchia C.To investigate the effect of plasma concentrations obtained by a low dose constant rate infusion (CRI) of racemic ketamine or S-ketamine on the nociceptive withdrawal reflex (NWR) in standing ponies. Methods: Prospective, blinded, cross-over study. Methods: Six healthy 5-year-old Shetland ponies. Methods: Ponies received either 0.6 mg kg(-1) racemic ketamine (group RS) or 0.3 mg kg(-1) S-ketamine (group S) intravenously (IV), followed by a CRI of 20 microg kg(-1)minute(-1) racemic ketamine (group RS) or 10 microg kg(-1)minute(-1) S-ketamine (group S) for 59 minutes. The NWR was evoked by trans...
McGurrin MK, Physick-Sheard PW, Kenney DG.Transvenous electrical cardioversion (TVEC) has been developed for treatment of atrial fibrillation (AF) in horses. The relationship among patient variables, treatment response, and outcome in a typical referral population has not been evaluated. Objective: Patient variables such as age, sex, weight, and duration of arrhythmia affect prognosis for response to treatment and the energy level at which cardioversion occurs. Methods: TVEC was applied to 72 episodes of lone AF in 63 client-owned performance horses, with the majority (54) being Standardbred racehorses. Methods: Catheterization of the...
Sanchez LC, Elfenbein JR, Robertson SA.To evaluate effects of butorphanol, acepromazine, and N-butylscopolammonium bromide (NBB) on visceral and somatic nociception and duodenal motility in conscious, healthy horses. Methods: 6 adult horses. Methods: Visceral nociception was evaluated by use of colorectal distention (CRD) and duodenal distention (DD) threshold. Somatic nociception was evaluated via thermal threshold (TT). Nose-to-ground height, heart rate, and respiratory rate were also measured. Each horse received each treatment in randomized order; investigators were not aware of treatments. Butorphanol was administered IV as a ...
Morello SL, Ducharme NG, Hackett RP, Warnick LD, Mitchell LM, Soderholm LV.To determine the phase and quantitate the electromyographic (EMG) activity of the genioglossus, geniohyoideus, hyoepiglotticus, omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles of clinically normal horses during strenuous exercise. Methods: 7 clinically normal adult horses (2 Thoroughbreds and 5 Standardbreds). Methods: Bipolar electrodes were surgically implanted in the aforementioned muscles, and horses were subjected to an incremental exercise test on a high-speed treadmill. The EMG, heart rate, respiratory rate, and static pharyngeal airway pressures were measured d...
Williams DC, Aleman M, Holliday TA, Fletcher DJ, Tharp B, Kass PH, Steffey EP, LeCouteur RA.The influence of sleep on the equine electroencephalogram (EEG) has not been well documented. Objective: The objectives were to develop a noninvasive method of electrode placement for recording the EEG in horses and to establish normal EEG parameters for the various states of vigilance. Findings are compared with previously published reports on equine sleep based on electrocorticography (ECoG). Methods: Five neurologically normal horses. Methods: Overnight EEGs were recorded digitally in association with simultaneous videotaping of the horses' behavior. Data were analyzed by visual inspection,...
Gehlen H, Haubold A, Rohn K, Stadler P.In the present study we examined, if in Icelandic horses an increase in heart and/ or breathing rate is physiological and breed dependend or a sign of a pulmonary or cardiac disease. Therefore we examined 37 Icelandic horses with the prereport of being healthy. During clinical lung examination four horses showed symptoms of a pulmonary disease like increased breathing rate and enforced breathing at rest. These horses were excluded from the study. The other 33 horses were clinically normal. 17 of these horses were unridden (untrained) and 16 horses were regularly worked (trained). After clinica...
Driscoll N, Baia P, Fischer AT, Brauer T, Klohnen A.Large colon resection and anastomosis (LCRA) is the most aggressive method of surgical management of a colon with questionable viability. Currently, published studies are comprised mostly of broodmares and discuss short-term survival. Objective: To determine the prognosis for survival after LCRA in a diverse population of horses, report the incidence of post operative complications, and determine if associations between analysed variables and survival rate exist. Methods: The medical records of 52 horses that underwent LCRA were evaluated. Data were used to identify univariable associations wi...
Ennezat PV, Darchis J, Lamblin N, Tricot O, Elkohen M, Aumégeat V, Equine O, Dujardin X, Saadouni H, Le Tourneau T, de Groote P, Bauters C.Although mitral regurgitation (MR) has been associated with an increased risk of death and heart failure after myocardial infarction (MI), the relationship between post-MI MR and left ventricular (LV) remodeling has not been entirely clarified. In addition, the optimal timing for assessing MR after MI remains unknown. Methods: Post-MI MR was assessed by Doppler echocardiography at hospital discharge (baseline) and after 3 months in 261 patients with an inaugural anterior MI. We studied LV remodeling during a 1-year period and clinical follow-up after 3 years, according to MR severity at baseli...
Lépiz ML, Keegan RD, Bayly WM, Greene SA, McEwen MM.The Fick and thermodilution (TD) methods are two currently popular techniques for determination of cardiac output (CO) in adult horses. To our knowledge, a comparison of these two techniques has not been reported. Six healthy, resting, fit, adult horses of either sex and weighing 516.5+/-33.2 kg (mean+/-SD) were instrumented to enable measurement of cardiac output. Resting CO was determined by the Fick method and by thermodilution while the horses stood quietly in the stocks. Fick and thermodilution CO measurements were repeated under conditions of increased cardiac output achieved with the us...
Dória RG, Valadão CA, Duque JC, Farias A, Almeida RM, Netto AC.To evaluate the cardiorespiratory and behavioural effects of epidural xylazine (XYL) or clonidine (CLO) in horses. Methods: Blinded, randomized experimental study. Methods: Twelve healthy Arabian yearling horses weighing 117-204 kg were randomly allocated into two groups: XYL (n = 6) and CLO (n = 6). Methods: An epidural catheter was inserted and a facial arterial catheter was placed and the next day the horses were restrained in stocks. Baseline values for heart (HR) and respiratory (RR) rates, arterial pressure and behavioural responses were evaluated before (T0) and 10, 20, 30, 45, 60, 90 a...
Wagner AE, Mama KR, Steffey EP, Hellyer PW.To determine whether infusion of xylazine (XYL) and ketamine (KET) for 30 minutes after isoflurane administration in horses would result in improved quality of recovery from anesthesia, without detrimental cardiopulmonary changes. Methods: Randomized, blinded experimental trial. Methods: Seven healthy adult horses aged 6.4 +/- 1.9 years and weighing 506 +/- 30 kg. Methods: Horses were anesthetized twice, at least 1 week apart. On both occasions, anesthesia was induced by the administration of XYL, diazepam, and KET, and maintained with isoflurane for approximately 90 minutes, the last 60 minut...
Foreman JH, Barange A, Lawrence LM, Hungerford LL.The objective was to test the hypothesis that phenylbutazone (PBZ) alleviates lameness in an adjustable heart bar shoe model of equine foot pain. Eight Quarter Horse mares underwent 4-weekly treatments randomly: 0.9% saline placebo (SAL: 1 mL/45 kg body weight i.v.) with no lameness; SAL with lameness; PBZ (4.4 mg/kg body weight i.v.) with no lameness; and PBZ with lameness. Blinded heart rate (HR) and lameness score (LS) were assessed every 20 min for 2 h and then hourly through 9 h. At 1 h SAL or PBZ was administered. Jugular venous samples were obtained at hours 0, 1, 2, 4, 6, and 8 and wer...
Taylor NA, Caldwell JN, Dyer R.The hottest months on northern Australian cattle stations are from September to November, and it is during these months that horseback cattle mustering occurs. Stockmen wear clothing that restricts heat loss, and protective helmets have recently been introduced. Anecdotal evidence points to the possibility that helmets may increase the probability of developing heat illness, or reducing workplace performance. In this project, we quantified the working (thermal) environment on such cattle stations, and measured the metabolic demands on, and concurrent physiological strain in stockmen during mus...
Frank N, Buchanan BR, Elliott SB.To determine the effects of long-term oral levothyroxine sodium (L-T(4)) administration on serum thyroid hormone concentrations, thyroid gland function, clinicopathologic variables, and echocardiographic examination measurements in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Every 4 weeks, physical examinations were performed; blood samples were collected for CBC, plasma biochemical analyses, and assessments of serum total triiodothyronine (tT(3)) and thyroxine (tT(4)) concentrations. Plasma creatine kinase MB activity ...
Williams CA, Gordon ME, Betros CL, McKeever KH.Eight mature (12 +/- 2 yr; MAT) and 5 older (22 +/- 2 yr; OLD) Standardbred mares were used to test the hypothesis that aging and exercise training would alter apoptosis in white blood cells and antioxidant status. The horses were housed indoors overnight (16 h/d) in 3 m x 3 m stalls and were turned out in a drylot during the day. They were fed a diet consisting of total mixed ration, hay cubes fed ad libitum or an equine senior diet plus grass hay. Horses were trained for 20 to 30 min/d, 3 to 5 d/wk for 8 wk at a submaximal work intensity between 60 to 70% of maximal heart rate. A graded exer...
Christensen JW, Malmkvist J, Nielsen BL, Keeling LJ.In fear-eliciting situations, horses tend to show flight reactions that can be dangerous for both horse and man. Finding appropriate methods for reducing fearfulness in horses has important practical implications. Objective: To investigate whether the presence of a calm companion horse influences fear reactions in naive subject horses. Objective: The presence of a habituated (calm) companion horse in a fear-eliciting situation can reduce fear reactions in naive subject horses, compared to subject horses with a nonhabituated companion (control). Methods: Minimally handled (n = 36), 2-year-old s...
Noble GK, Brockwell YM, Munn KJ, Harris PA, Davidson HP, Li X, Zhang D, Sillence MN.L-tryptophan is a common ingredient in equine calmative products, but its effectiveness has not been demonstrated in horses. Objective: To determine whether a commercial dose of L-tryptophan increases plasma tryptophan and alters behaviour in horses fed a roughage or concentrate meal. Methods: L-tryptophan (6.3 g) or placebo (water) was administered per os in a cross-over design, to 12 Thoroughbred horses (503 +/- 12.1 kg bwt), just before a meal of lucerne hay or oats. Plasma tryptophan was measured by gas chromatography. Horse behaviour was observed in an empty enclosure, then in the presenc...
Gehlen H, Sundermann T, Rohn K, Stadler P.This study measured plasma atrial natriuretic peptide (ANP) concentration in horses with heart valve regurgitations (HVR) with and without atrial and ventricular dilatation. Background: In humans and small animals, plasma ANP concentration is increased in heart disease and correlates with the severity of clinical signs and heart enlargement. Methods: Ten healthy horses (control) and 36 horses with HVR were evaluated by auscultation, electrocardiography, echocardiography, and determination of plasma ANP. Results: Control horses demonstrated mean plasma ANP concentration of 21+/-5.4 pg/mL. Of th...
Kozelek P, Holcik J, Sedlinska M.The paper describes experiments and their results that offered an insight to relationship between RR and QT intervals in equine ECG signals recorded under various conditions. In contrast to human heart in a great number of cases the QT intervals prolonged with a heart rate acceleration. Peak-to-peak differences between maximum and minimum RR intervals during the excitation response in non-standard responses were twice as smaller as in standard responses and the lengths of QT intervals were significantly longer in the non-standard records. This fact means that the electrical processes in equine...
Gehlen H, Haubold A, Stadler P.The aim of this study was to establish echocardiographic reference values for healthy Icelandic horses. For this purpose cardiologic examinations were performed on 44 healthy trained and untrained Icelandic horses without known cardiologic or pulmonary disease. The atrial diameter of the trained horses were significantly greater than in the untrained horses and the left ventricular free wall diameter was also higher in the trained than in the untrained horses. These findings confirm that the changes of the heart caused by training which have previously been described by other authors in warmbl...
Bellei MH, Kerr C, McGurrin MK, Kenney DG, Physick-Sheard P.To describe management of anesthesia for transvenous electrical cardioversion (TVEC) in horses and report perianesthetic complications. Methods: Retrospective case series. Methods: 62 horses with atrial fibrillation and without underlying cardiac disease and 60 horses without atrial fibrillation. Methods: Medical records of horses with atrial fibrillation anesthetized for TVEC were reviewed, as were records of horses without atrial fibrillation anesthetized for magnetic resonance imaging (MRI). The TVEC group horses were compared with MRI group horses for incidence of intraoperative bradycardi...
Seddighi MR, Mohri M.To evaluate some of the clinical and laboratory parameters following diazepam-acepromazine, thiopental, and halothane anesthesia in Caspian ponies. Methods: Prospective experimental trial. Methods: Six healthy Caspian ponies of both sexes, aged 11 +/- 3 years and weighing 318 +/- 71 kg. Methods: The ponies were pre-medicated with diazepam (0.2 mg kg(-1)) and acepromazine (0.05 mg kg(-1)) IV. Sodium thiopental 5% was administered IV, 10 minutes later and anesthesia was maintained with halothane in oxygen for 1 hour. Heart and respiratory rates, mean arterial blood pressure, cardiac rhythm, and ...
Momozawa Y, Terada M, Sato F, Kikusui T, Takeuchi Y, Kusunose R, Mori Y.The aim of the study was to determine parameters reflecting equine anxiety trait by comparing results obtained in a behavior test and an anxiety score assessed by familiar caretakers in response to a questionnaire. In the behavior test, horses were individually led into a novel room by their caretakers and loosely tethered to decrease excessive movement using the common cross-tying technique with two leads and breakable plastic cords. The horses initially remained with their caretaker for 2 min; the caretaker then left and the subject animal was left alone for 2 min. The latency to break the p...
Razavizadeh AT, Mashhadi AG, Paphan AA.An observational field study was performed on a well-know purebred horses in Iran (Khozestan-Arab horse). The study was conducted on 105 apparently healthy horses. To find the prevalence of cardiac dysrhythmias in different sexes and ages, the horses were divided into 2 sexes (63 females and 42 males) and three age groups (0-4, 4-8, > 8 years old). After taking the history and performing clinical examination, ECG was obtained on a base apex lead system with the paper speed of 25 mm sec(-1) and sensitivity of 10 or 5 mm mv(-1) at rest. The electrocardiograms were evaluated according to the crit...
Curtis RA, Kusano K, Evans DL, Lovell NH, Hodgson DR.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...
Rabbogliatti V, Amari M, Brioschi FA, Di Cesare F, Zani DD, De Zani D, Di Giancamillo M, Cagnardi P, Ravasio G.A balanced anaesthetic protocol is a common concept in modern veterinary anaesthesia and aims to maintain good intraoperative cardiopulmonary function. In horses, alpha-2-agonists produce sedation and analgesia and have been shown to reduce inhalational anaesthetic requirements when administered intravenously. Furthermore, these drugs can improve recovery quality. Preliminary investigations of subcutaneous dexmedetomidine administration in humans demonstrated a reduced haemodynamic impact if compared with the intravenous route suggesting that dexmedetomidine is adequately absorbed with both ad...
Sandersen CF, Detilleux J, Delguste C, Pierard L, van Loon G, Amory H.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...
Johansson AM, Gardner SY, Atkins CE, LaFevers DH, Breuhaus BA.Recurrent airway obstruction (RAO) is common in horses. Although pulmonary artery (PA) pressure increases during RAO, cardiac function in horses with RAO has received limited attention. Objective: The purpose of this study was to noninvasively determine the cardiovascular effects of acute pulmonary obstruction (APO) in horses with RAO and their reversibility. Methods: Five geldings with RAO, inducible by exposure to moldy hay, were studied. Methods: Pulmonary mechanics, echocardiography, serum troponin I concentrations, arterial blood gases, and hematocrit were obtained before and after 7 days...
Manohar M.1. Transmural distribution of myocardial blood flow was studied using 15 micron diameter radionuclide-labelled microspheres in six normal ponies and nine splenectomized ponies at rest, and during maximal exercise performed without as well as with adenosine infusion (3 microM kg-1 min-1). The splenectomized ponies were also studied during submaximal exercise performed at 75% of the workload. 2. Maximal exertion in normal ponies increased heart rate (348%), mean arterial blood pressure (40.9%), rate-pressure product (563%), arterial O2 content (43.2%), and mean pulmonary artery pressure (247%). ...
O'Reilly C, Zoller J, Sigler D, Vogelsang M, Sawyer J, Fluckey J.Despite the fact that horseback riding is a popular sport, there is little information available on horseback riding as a physical activity. The objective of this experiment was to quantify energy expenditure of participants (n=20) during three riding tests: a 45min walk-trot-canter ride (WTC), a reining pattern ride and a cutting simulation ride while wearing a telemetric gas analyzer. Total energy expenditure (tEE), mean and peak metabolic equivalents of task (MET), heart rate (HR), respiratory frequency (RF), relative oxygen consumption (relVO2), and respiratory exchange ratio (RER) were as...
Forster HV, Pan LG, Bisgard GE, Dorsey SM, Britton MS.We characterized the temporal patterns of pulmonary O2 consumption (VO2) and CO2 excretion (VCO2) in exercising ponies. We also assessed the cardiac, ventilatory, and hematologic contributions to the VO2-VCO2 changes during exercise. At five moderate treadmill work loads in normal ponies, VO2 and VCO2 generally increased progressively throughout the 1st min reaching, respectively, approximately 95 and 80% of steady state by 45-60 s. Between 1 and 1.5 min, Vo2 and Vco2 were either stable or they decreased 300-500 ml, but then each increased slightly, reaching steady-state levels between 3 and 5...
McCarthy RN, Jeffcott LB.Six Standardbred horses underwent a 14-week training programme on a treadmill. The training schedule consisted of five weeks of slow work of six to 12 km/day at 5 m/sec. This was followed by a nine week interval programme increasing in its intensity so that for the last three weeks the horses did three to four intervals/day from 600 to 1000 m at or above maximum heart rate. Ultrasound velocity through the third metacarpus showed a significant increase as a result of training. There was also a significant increase in modulus of elasticity, but no change in bone mineral content, bone mineral den...
Jesty SA, Kraus MS, Gelzer AR, Rishniw M, Moise NS.Whether electrical cardioversion of cardiac arrhythmias results in cardiomyocyte damage is unknown. Objective: To describe effect of transvenous electrical cardioversion (TVEC) on plasma cardiac troponin I (cTnI) concentration in horses. Methods: All horses presented to the Cornell University Hospital for Animals for cardioversion of atrial fibrillation between May 2006 and October 2008 were eligible for inclusion in the study. Owners of 14 horses elected for TVEC and each horse was then enrolled (16 procedures). Methods: Prospective observational study measuring concentrations of plasma cTnI ...
Reef VB, Lalezari K, De Boo J, van der Belt AJ, Spencer PA, Dik KJ.Pulsed-wave Doppler echocardiography was performed on 30 clinically normal 1- to 6-year-old racing Standardbreds. There were 13 females, 13 geldings, and 4 stallions. Cardiac disease was not detected with M-mode, 2-dimensional real-time or pulsed-wave Doppler echocardiography. Normal flow velocities for right and left atrial outflow, right and left ventricular outflow, the aorta, and pulmonary artery were determined. Peak flow velocities for right and left atrial outflow occurred during the rapid filling phase and were higher toward the mitral valve (mean, 0.70 +/- 0.24 m/s) than toward the tr...
Vera L, De Clercq D, Van Steenkiste G, Decloedt A, Chiers K, van Loon G.Aortic rupture is more common in Friesians compared to Warmbloods, which might be related to differences in arterial wall composition and, as such, arterial wall stiffness (AWS). Currently, nothing is known about differences in AWS between these breeds. Objective: Comparison of AWS parameters and noninvasive blood pressure between Friesians and Warmbloods. Methods: One hundred one healthy Friesians and 101 age-matched healthy Warmbloods. Methods: Two-dimensional and pulsed-wave Doppler ultrasound examination was performed of the aorta, common carotid artery, and external iliac artery to define...
Ohta M, Oku K, Yamanaka T, Mizuno Y.Eighty-five thoroughbred racehorses with various types of fracture were subjected to arthroscopic surgery (44 horses) or internal fixation (41 horses) under sevoflurane anesthesia. The mean end-tidal sevoflurane concentration during anesthesia ranged from 2.5 to 2.8%. PaCO2 was maintained between 50 and 65 mmHg by controlled ventilation. The mean arterial blood pressure was maintained above 65 mmHg by infusion of dobutamine and fluids, however, heart rate significantly increased with time. Recovery from anesthesia was calm and smooth in almost all cases. No apparent complication was observed d...
Umar MA, Yamashita K, Kushiro T, Muir WW.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/...
Kuhl J, Nagel C, Ille N, Aurich JE, Aurich C.In the present study we have evaluated a possible stress reaction in response to two different PGF2α analogs-luprostiol and D-cloprostenol--and their effects on estrous cycle characteristics. In a cross-over-design eight mares received in alternating order either luprostiol (Treatment LUP; 3.75 mg im), D-cloprostenol (Treatment CLO; 22.5μg im) or saline (Treatment CON; NaCl 0.9% 0.5ml im) on day 8 after ovulation. Injection of either LUP or CLO, but not of CON resulted in a significant decline of progesterone concentration in plasma to baseline concentrations within two days (time: p<0.00...
Bringewatt T, Hopster K, Kästner SB, Rohn K, Ohnesorge B.The influence of a modified open lung concept (mOLC) on pulmonary and cardiovascular function during total intravenous anaesthesia (TIVA) in horses was evaluated. Forty-two warmblood horses (American Society of Anesthesiologists class 1 to 2), scheduled for elective surgery (mean [sd] weight 526 [65] kg, age 6.4 [5.4] years) were randomly divided into three groups: ventilation with mOLC, intermittent positive-pressure ventilation (IPPV), and spontaneous breathing. Premedication (0.8 mg/kg xylazine), induction (2.2 mg/kg ketamine and 0.05 mg/kg diazepam) and maintenance of anaesthesia with TIVA...
Stachurska A, Wiśniewska A, Kędzierski W, Różańska-Boczula M, Janczarek I.Horses in a herd develop and maintain a dominance hierarchy between all individuals. There are many situations in riding facilities and studs in which horses have to be separated out of a group. The aim of the study was to determine the rate of behaviours, level of locomotor activity and cardiac activity variables in a herd of horses during a short social separation of individuals differently ranked in the dominance hierarchy. Twelve adult Arabian mares were involved. A behavioural test had been performed before the main experiment to determine the rank order of the mares in this social herd. ...
Wilkins PA, Gleed RD, Krivitski NM, Dobson A.Seven Standardbred horses were exercised on a treadmill at speeds (approximately 12 m/s) producing maximal heart rate, hypoxemia, and a mean pulmonary arterial pressure of approximately 75 mmHg. Extravascular lung water was measured by using transients in temperature and electrical impedance of the blood caused by a bolus injection of cold saline solution. Lung water was approximately 3 ml/kg body wt when standing but did not increase significantly with exertion. We conclude that any increase in fluid extravasation from the pulmonary hypertension accumulates in the lung at a level that is less...
MacKenzie G, Snow DH.An evaluation of acepromazine (0.5 mg/kg intramuscularly), azaperone (0.7 and 0.9 mg/kg intramuscularly) and xylazine (2.0 mg/kg intramuscularly) as chemical restraining agents was carried out in seven horses. (Xylazine and azaperone were used at the recommended dose rates; acepromazine at five times the recommended dose rates). Of the three drugs administered only azaperone produced sufficient sedation in all the horses to allow a percutaneous needle muscle biopsy to be taken from six muscles. With acepromazine and xylazine this procedure could be successfully carried out in five and four hor...
Terada M, Momozawa Y, Komano M, Kusunose R, Sato F, Saito TR. 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...
van Loon G, De Clercq D, Tavernier R, Amory H, Deprez P.Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These...
British medical journalSeptember 13, 1980
Volume 281, Issue 6242 699-702 doi: 10.1136/bmj.281.6242.699
English TA, Cooper DK, Cory-Pearce R.The major factors contributing to the recommencement of clinical heart transplantation in the United Kingdom last year were the steadily improving results from Stanford University, the clarification of the diagnosis of brain death, and advances in preserving donor hearts. Twelve men aged 16 to 52 years received heart transplants at Papworth Hospital from January 1979 to July 1980. Six had cardiomyopathies and six ischaemic heart disease. The donors were aged 16 to 35 (mean 21) years. A combination of road and air transport was used to transport the heart to Papworth in seven cases. The total d...
Roşu O, Melega I, Evans AL, Arnemo JM, Küker S.Feral horses are immobilized for a variety of reasons including population control via contraceptives. Although opioid combinations have been successfully used for immobilization of feral horses, there is a need for combinations using drugs that are more readily available and present less of a human health hazard. We evaluated the chemical immobilization with physiological measurements and blood gas analyses of 91 free-ranging feral horses () remotely immobilized with a combination of 30 mg medetomidine and 775 mg ketamine in a single disposable 6 ml dart. During immobilization, heart rate, re...
Young LE, Blissitt KJ, Clutton RE, Molony V.To evaluate temporal hemodynamic effects of dobutamine in horses anesthetized with halothane. Methods: 8 adult Thoroughbreds. Methods: Anesthesia was induced by i.v. administration of romifidine and ketamine and maintained using halothane in oxygen. After 60 minutes, dobutamine was administered i.v. for 60 minutes at 4 micrograms/kg of body weight/min. Measurements of left ventricular function were obtained by transesophageal echocardiography and cardiac catheterization. Results: Mean, systolic, diastolic, aortic, pulmonary arterial, and left and right ventricular end-diastolic and systolic pr...
Diego R, Douet C, Reigner F, Blard T, Cognié J, Deleuze S, Goudet G.Transvaginal ultrasound-guided follicular punctures are widely used in the mare for diagnosis, research, and commercial applications. The objective of our study was to determine their influence on pain, stress, and well-being in the mare, by evaluating heart rate, breath rate, facial expression changes, and salivary cortisol before, during, and after puncture. For this experiment, 21 pony mares were used. Transvaginal ultrasound-guided aspirations were performed on 11 mares. After injections for sedation, analgesia, and antispasmodia, the follicles from both ovaries were aspirated with a needl...
Shawaf T, Al Mubarak A, Eidi H, El-Bahr SM.Influence of heat or cold stress in sedated animals is unclear and requires further investigations. The present study aimed to evaluate the season's effects on some clinical, hematological parameters and blood cortisol level in sedated Arabian horses with xylazine. Therefore, seven Arabian horses were used to investigate heart and respiratory rates, and capillary refill time and serum cortisol level were recorded before (0) and at 5, 15, 60, and 180 minutes postsedation. Heparinized venous samples were collected before (0) and 3 hours postsedation for analysis of hematological analysis. Arte...
Trachsel DS, Grenacher B, Weishaupt MA, Schwarzwald CC.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...
Lindner A, Esser M, López R, Boffi F.In endurance racing the heart rate (HR) of horses in the veterinary gates has to reach a maximum set to continue racing. There is no literature on the relationship between resting HR (HRresting) and HR after exercise (HRrecovery). This relationship was examined in seven horses and the results were related to their v (speed at which the blood lactate concentration is 4 mmol/L). Horses were submitted to an exercise test to determine v. Thereafter, horses were exercised on a treadmill in randomized order for 10 and 60 min at different speeds. HR was measured before exercise and several times unti...
Nath LC, Forbes G, Elliott AD, Tomren V, Ryan A, Franklin SH.AliveCor is a smartphone electrocardiography device (iECG) providing automated heart rate (HR) and rhythm determination. Atrial fibrillation (AF) in horses often is paroxysmal and rapid ECG acquisition is needed for diagnostic confirmation. iECGs were collected post-race from 15 horses with AF and 64 horses in sinus rhythm (SR). Results of manual assessment were compared to 3 commercial algorithms for HR and rhythm. Agreement between manually derived HR (HRM ) and HR derived by the AliveECG Vet (HRVET ) and Kardia version-1 (KV1 HR) and Kardia advanced (KADV HR) algorithms was quantified by th...
Hubbell JA, Muir WW, Sams RA.We determined the cardiopulmonary changes in horses given guaifenesin alone and in the same horses given xylazine (IV) immediately before administration of guaifenesin. In addition, plasma guaifenesin concentrations were determined in horses and 2 pregnant mares and compared with previously published values in ponies. The dose of guaifenesin necessary to produce lateral recumbency in adult horses was 134 +/- 34 mg/kg (mean +/- SD). The administration of guaifenesin caused insignificant (P less than 0.05) changes in heart rate, respiratory rate, right atrial pressure, pulmonary arterial pressur...
François I, Lepage OM, Schramme MC, Salciccia A, Detilleux J, Grulke S.To report findings, outcome and determine variables associated with survival in horses with acquired inguinal hernia (AIH). Methods: Retrospective study. Methods: A total of 98 cases in 97 horses. Methods: The medical records (2005-2020) of horses diagnosed with AIH were reviewed. Retrieved data included signalment, history, clinical variables, surgical aspects, postoperative complications, and short- and long-term outcomes. Logistic regression analyses were used to determine factors associated with short-term survival (p < .05). Results: Manual reduction was attempted in a third of the...
