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.
Gómez-Torres F, Ballesteros-Acuña L, Ruíz-Sauri A.Atrioventricular node is responsible for delaying the passage of the electrical impulse to ventricles in order to protect them from fast depolarizations coming from the atria. The importance of this study is to identify the morphological variations of the components of atrioventricular zone that affect the conduction system and its clinical relationship in different species of mammals. We analyzed ten human hearts, nine from horses, eight from pigs, and five from dogs without a clinical history of cardiac pathologies. Histological section thickness of 5 μm were obtained with a microtome and ...
Klous L, Siegers E, van den Broek J, Folkerts M, Gerrett N, van Oldruitenborgh-Oosterbaan MS, Munsters C.In this study, we examined the effects of pre-cooling on thermophysiological responses in horses exercising in moderate environmental conditions (average wet bulb globe temperature: 18.5 ± 3.8 °C). Ten international eventing horses performed moderate intensity canter training on two separate days, and were either pre-cooled with cold-water rinsing (5-9 °C for 8 ± 3 min; cooling) or were not pre-cooled (control). We determined velocity (V), heart rate (HR), rectal temperature (T), shoulder and rump skin temperature (T and T), plasma lactate concentration (LA), gross sweat loss (GSL), and lo...
Nagel C, Melchert M, Aurich C, Aurich J.Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland ( = 6), Haflinger ( = 8), and Warmblood pregnancies ( = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares ( < 0.05). Progestin ( < 0.001) and cortisol ( < 0.05) concentrati...
Gehlen H, Faust MD, Grzeskowiak RM, Trachsel DS.Heart rate variability (HRV) is a noninvasive technique to detect changes in the autonomous nervous system. It has rarely been investigated in horses with colic. Therefore, the objective was to assess the evolution of HRV parameters and cortisol concentrations in horses with colic. The 43 horses included in this study were categorized into three groups according to the treatment (1, surgical; 2, conservative; 3, euthanized). The HRV and laboratory variables were measured at admission (T1), the day after admission (T2), and at discharge (T3) and compared between groups and over time with an ANO...
Youngblood CD, Hodgson DS, Beard WL, Song Y, Prakash P, Heflin LV.Recumbency affects respiratory mechanics and oxygenation in anesthetized horses. Changes in pleural and abdominal pressures that can impair ventilation have not been described in all recumbencies. The objective of this study was to determine the effects of patient positioning on transdiaphragmatic pressure and selected hemodynamic variables. Horses were maintained under total intravenous general anesthesia with nasal oxygen supplementation. Transnasal balloon catheters in the stomach and thoracic esophagus were used to measure intrathoracic and gastric pressures in standing horses and in anest...
Kiely M, Warrington GD, McGoldrick A, Pugh J, Cullen S.Kiely, M, Warrington, GD, McGoldrick, A, Pugh, J, and Cullen, S. Physiological demands of professional flat and jump horse racing. J Strength Cond Res 34(8): 2173-2177, 2020-No information is currently available on the effect of race distance on the physiological demands of jockeys. This study aimed to quantify the respective demands of short and long flat and jump race distances. Twenty professional jockeys (10 flat and 10 jump) participated in the study. The subjects initially performed a graded incremental exercise test to volitional exhaustion on a treadmill to determine the peak heart rat...
Bauquier J, Tudor E, Bailey S.Doramapimod, a p38 MAPK inhibitor, is a potent anti-inflammatory drug that decreases inflammatory cytokine production in equine whole blood in vitro. It may have benefits for treating systemic inflammation in horses. Objective: To determine whether doramapimod is well tolerated when administered IV to horses, and whether it has anti-inflammatory effects in horses in a low-dose endotoxemia model. Methods: Six Standardbred horses. Methods: Tolerability study, followed by a blinded, randomized, placebo-controlled cross-over study. Horses were given doramapimod, and clinical and clinicopathologica...
Decloedt A, Van Steenkiste G, Vera L, Buhl R, van Loon G.Atrial fibrillation (AF) is the most common clinically relevant arrhythmia in horses, with a reported prevalence up to 2.5%. The pathophysiology has mainly been investigated in experimental animal models and human medicine, with limited studies in horses. Atrial fibrillation results from the interplay between electrical triggers and a susceptible substrate. Triggers consist of atrial premature depolarizations due to altered automaticity or triggered activity, or local (micro)reentry. The arrhythmia is promoted by atrial myocardial ion channel alterations, Ca2+ handling alterations, structural ...
Arrazola A, Merkies K.Equine-assisted activities (EAA) for human well-being and health rely on human-horse interactions for therapeutic effect. At-risk participants with mental and emotional difficulties can show poor social skills and functioning relationships, potentially leading to unsuccessful human-horse interaction in EAA. This study addresses the effect of the attachment style (AS) of at-risk adolescents on horse physiology and behaviour during an equine-facilitated learning (EFL) program. Thirty-three adolescents participated in a 10-week EFL program with nine therapy horses (the same therapy horse per adol...
Cherdchutham W, Koomgun K, Singtoniwet S, Wongsutthawart N, Nontakanun N, Wanmad W, Petchdee S.The objective of this study was to assess a new lead system method to improve electrocardiographic measurement in horses. Methods: Twenty-two horses with an average age of 8.8±0.8 years were enrolled in this study. Horses were divided into two groups, consisting of a control group (n=11) and athlete group (n=11). Electrocardiography (ECG) and echocardiography were performed to provide information on the structure and function of the heart. Two lead systems, base apex and modified precordial leads, were used for the electrocardiogram to assess the cardiac electrophysiological functions. Result...
Ferreira da Cruz FS, Natalini CC, Pellin de Molnar BF, Beatriz da Silva Serpa P, Tisotti T, Midon M, Desessards de La Côrte F.This study aimed to evaluate the effects and lameness degree in horses administered tramadol after the P-glycoprotein (P-gp) enteric inhibitor ivermectin. Six horses were randomly distributed into three groups, which received two different doses of tramadol by a nasogastric tube: 1 mg/kg (tramadol group 1(GT1)), 4 mg/kg (tramadol group 4 (GT4)), and tramadol 1 mg/kg combined with ivermectin 0.2 mg/kg PO (ivermectin tramadol group (GT1 + Ive)), with one-week washout interval. Heart rate (HR), respiratory rate (RR), intestinal motility, body temperature, and the degree of lameness were eval...
Fretheim-Kelly Z, Fjordbakk CT, Fintl C, Krontveit R, Strand E.Bits have often been incriminated as a cause of upper respiratory tract obstruction in horses; however, no scientific studies are available to confirm or refute these allegations. Clinical signs of dynamic laryngeal collapse associated with poll flexion (DLC) are induced when susceptible horses are ridden or driven into the bit. Objective: To determine whether use of Dr Cook's™ Bitless Bridle, instead of a conventional snaffle bit bridle, would reduce the severity of DLC in affected horses measured objectively using inspiratory tracheal pressures. Methods: Intervention study using each horse...
Léguillette R, Bond SL, Lawlor K, Haan T, Weber LM.A greater understanding of exercise physiology and biochemistry is required for the sport horse disciplines, including show jumping. Conditioning of horses for show jumping is empirical because they are primarily trained on flat ground, however the equivalent workload between jumping and flat work is currently unknown. The objectives of the study were therefore to compare the physiological demands of Warmblood show jumpers over a standardized 1.10 m course vs a 600 m standardized incremental exercise test on flat ground, and to report reference field test values for competitive show jumpin...
Knych HK, Wilson WD, Vale A, Kass PH, Steffey EP, Jones JH, Arthur RM.Although controversial, due to its reported effectiveness in attenuating bleeding associated with exercise-induced pulmonary hemorrhage (EIPH), furosemide is currently a permitted race day medication in most North American racing jurisdictions. The objective of this study was to assess the efficacy of furosemide in reducing the presence and severity of EIPH when administered 24 hr prior to strenuous treadmill exercise. Eight exercised Thoroughbred horses received saline or 250 mg of furosemide either 4 or 24 hr prior to high-speed treadmill exercise in a balanced 3-way cross-over design. Bl...
Restan AZ, Camacho AA, Cerqueira JA, Zacché E, Kirnew MD, Loureiro BA, Silva SB, Moranza HG, Ferraz GC.The dogs' responses to training exercise are seldom monitored using physiological variables, and cardiac autonomic regulation (CAR) is a relevant determinant of endurance-training adaptation. There are studies in the literature establishing that regular exercise could interfere with CAR in dogs, measured by heart rate and vagal-derived indexes of heart-rate-variability (HRV). However, few studies were found using a prescribed training program based on the lactate threshold (LT) to determine HRV by a 24-h Holter analysis. The purpose of this study was to test whether an endurance-training progr...
Sodré TDRP, Sousa LN, Silva CA, Santos JM, Sampaio MQ, Coni ROS, Dantas RTS, Ferreira APG, Manso Filho HC, Fazio F, Coelho CS.Vaquejada is an important Brazilian equine discipline. Understanding physiological adaptations of these athletes is crucial to improve properly performance, guaranteeing welfare. The objective of this study was to evaluate the influence of three vaquejada simulation tests (VST) on physiological parameters of horses and standardize a possible rest interval between races. Ten clinically healthy Quarter horses, 8.9 ± 4.3 year-old and 441.3 ± 25.0 kg, executed three VST, 5 days apart from each other. Vaquejada simulation tests consisted of two horses, a puller, and a helper, running with a bul...
Masko M, Domino M, Lewczuk D, Jasinski T, Gajewski Z.A treadmill is an important tool in the equine analysis of gait, lameness, and hoof balance, as well as for the evaluation of horse rehabilitation or poor performance including dynamic endoscopy. Before all of these uses, horses have to be habituated to a treadmill locomotion. We used principal component analysis to evaluate the relationship between aspects of the horse's temperament and emotional response, and progress in the behavioral habituation to a treadmill. Fourteen horses were tested, by the same familiar handler, using the novel object test, the handling test, and both positive and n...
Hopster K, Soma LR, Li X, Hopster-Iversen C, Boston RC, Driessen B.Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg hr for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration-time curves following bolus an...
Welch-Huston B, Durward-Akhurst S, Norton E, Ellingson L, Rendahl A, McCue M.Cardiac arrhythmias are commonly auscultated during routine physical examinations in horses and determining the underlying electrical abnormality using an ECG is important. The most commonly used device is a three-lead base apex system (Televet), however few practitioners carry this for routine visits. With recognition of the utility of smartphone-based ECGs in humans, dogs and ruminants, the AliveCor single-lead bipolar smartphone-based ECG has gained popularity. The objective of this study was to determine if AliveCor and Televet ECG measurements were comparable in healthy horses using multi...
Pallarols NB, Lamuraglia R, Guglielminetti A, Ortiz de Elguea MF, Carossino M, Funcia JP.Xylazine and remifentanil in constant rate infusion (CRI) could be used for sedation in horses without adverse effects. The objective was to evaluate behavioral and cardiopulmonary effects of an intravenous (IV) infusion of xylazine and remifentanil for sedation in horses. Xylazine (0.8 mg/kg IV) followed after 3 minutes by a CRI of xylazine and remifentanil (0.65 mg/kg/h and 6 μg/kg/h, respectively) was administered in 10 healthy horses for 60 minutes. Sedation, ataxia, and cardiopulmonary, hematological, and blood gases variables were evaluated. Heart rate decreased significantly durin...
Eberhardt C, Mitchell KJ, Schwarzwald CC.The mechanical function of the left atrium (LA) plays a pivotal role in modulation of left ventricular filling. Assessment of LA function might be a clinically useful prognostic tool for horses with mitral regurgitation or atrial fibrillation. However, the most accurate, reliable, and clinically useful methods to assess LA myocardial function are yet to be determined. The objective of this study was to describe the methods for quantification of LA wall motion using two-dimensional speckle tracking (2DST) echocardiography in healthy Warmblood horses to quantify measurement variability, to calcu...
Fintl C, Krontveit R, Risberg Å, Hanche-Olsen S, Slack J.The Norwegian-Swedish Coldblooded Trotter (NSCT) is an important breed in Norwegian and Swedish harness racing. In spite of this, little is known about its cardiac measurements and factors that may influence these. The aims of this study were to establish reference intervals (RI) for a series of conventional echocardiographic variables, primarily of the left heart, in NSCTs in race training and to evaluate any effects age, gender, estimated body weight (EBW), number of starts and racing performance may have on these. Methods: Sixty-three apparently healthy NSCTs in race training. Methods: Obse...
Recchi L, Alvariza S, Benech A, Ruiz N, José Estradé M, Suarez G, Crosignani N.The purpose of this study was to evaluate the pharmacokinetics of oral amitriptyline in horses. Oral amitriptyline (1 mg/kg) was administered to six horses. Blood samples were collected from jugular and lateral thoracic vein at predetermined times from 0 to 24 hr after administration. Plasma concentrations were determined by high-performance liquid chromatography and analyzed using noncompartmental methods. Pharmacodynamic parameters including heart rate, respiration rate, and intestinal motility were evaluated, and electrocardiographic examinations were performed in all subjects. The mean m...
Meier M, Bettschart-Wolfensberger R, Schwarzwald CC, Portier K, Gysler A, Ringer SK.Dobutamine is routinely used to improve cardiovascular function in anaesthetized horses. However, dobutamine in conscious horses is insufficiently investigated. Ten research horses that were already instrumented for a preceding trial were included into the study. Cardiovascular variables were recorded and blood samples taken after instrumentation (Baseline), before starting dobutamine and after 10 min of dobutamine infusion (2 µg kg min ). A significant increase in systemic blood pressure, mean pulmonary artery pressure and right atrial pressure, and a decrease in heart rate were observe...
Munsters CCBM, Kingma BRM, van den Broek J, Sloet van Oldruitenborgh-Oosterbaan MM.In human sport science, the acute:chronic workload (ACWR) ratio is used to monitor an athlete's preparedness for competition and to assess injury risks. The aim of this study was to investigate whether acute and chronic workload calculations for external and internal loads (e.g. high-speed work distance and associated exertional effort) were associated with injury risk in elite eventing horses and to identify workloads performed by horses competing in different competition and at different fitness levels. Training load and injury data were collected from 58 international eventing horses (CCI2*...
Gretler SR, Finno CJ, McKemie DS, Kass PH, Knych HK.To describe the pharmacokinetics and selected pharmacodynamic variables of codeine and its metabolites in Thoroughbred horses following a single oral administration. Methods: Prospective experimental study. Methods: A total of 12 Thoroughbred horses, nine geldings and three mares, aged 4-8 years. Methods: Horses were administered codeine (0.6 mg kg) orally and blood was collected before administration and at various times until 120 hours post administration. Plasma and urine samples were collected and analyzed for codeine and its metabolites by liquid chromatography-mass spectrometry, and plas...
Sampaio BFB, DeRossi R, Vieira N, Milan B, Ávila LG.The objective of the study was to compare the effects of caudal epidural bupivacaine and dexmedetomidine (DEX) combination, with bupivacaine or DEX plain for perineal analgesia in mares. Six healthy saddle mares weighing 330-370 kg and aged 10-15 years were used in this study. Each mare was assigned to receive three treatments: 0.04 mg/kg 0.25% bupivacaine (BP), 2 μg/kg DEX (DX), or 0.02 mg/kg bupivacaine and 1 μg/kg DEX (BPDX). The order of treatments was randomized. All drugs were injected into the caudal epidural space (Co1-Co2) through a 16-G Tuohy epidural needle. After the epidur...
Bennet ED, Hayes ME, Friend L, Parkin TDH.Endurance competitions over distances of 80-160 km are required by Fédération Equestre Internationale (FEI) rules to be divided into a number of stages between three and six. These stages are also known as "loops". Veterinary inspections, designed to ensure horse welfare, are conducted at the end of each loop, with details recorded on a separate "vet card" for each horse. Objective: To identify risk factors recorded on vet cards that were associated with elimination at subsequent loops. Methods: Retrospective cohort study. Methods: Data relating to 3213 horse starts worldwide in internation...
Martins FC, Keating SC, Clark-Price SC, Schaeffer DJ, Lascola KM, DiMaio Knych H.To determine the physiologic and behavioral effects and pharmacokinetic profile of hydromorphone administered intravenously (IV) to horses. Methods: Prospective, randomized, crossover study. Methods: A group of six adult healthy horses weighing 585.2 ± 58.7 kg. Methods: Each horse was administered IV hydromorphone (0.025 mg kg; treatment H0.025), hydromorphone (0.05 mg kg; treatment H0.05) or 0.9% saline in random order with a 7 day washout period. For each treatment, physiologic, hematologic, abdominal borborygmi scores and behavioral data were recorded over 5 hours and fecal output was tota...
García-Gómez A, Guerrero-Barona E, García-Peña I, Rodríguez-Jiménez M, Moreno-Manso JM.To examine the effect of equine-assisted therapeutic interventions on users' heart rate variability, using this said variability as an objective biological variable related to stress levels. Methods: A systematic review has been carried out using the methodology suggested in the PRISMA declaration following systematic searches in academic databases. Results: 432 registers were initially identified; however, in the screening and suitability process, nine papers were included in the review. With one exception, all of them reported that equine-assisted therapeutic activities had a favourable effe...
Manohar M.The present study was carried out 1) to compare blood flow in the costal and crural regions of the equine diaphragm during quiet breathing at rest and during graded exercise and 2) to determine the fraction of cardiac output needed to perfuse the diaphragm during near-maximal exercise. By the use of radionuclide-labeled 15-micron-diam microspheres injected into the left atrium, diaphragmatic and intercostal muscle blood flow was studied in 10 healthy ponies at rest and during three levels of exercise (moderate: 12 mph, heavy: 15 mph, and near-maximal: 19-20 mph) performed on a treadmill. At re...
Muñoz A, Riber C, Santisteban R, Rubio MD, Agüera EI, Castejón FM.The cardiovascular and metabolic response to two cross-country events (CC*: preliminary level and CC*** advanced level) were analysed in 8 male eventing horses (4 Anglo-Hunter and 4 Anglo-Arabian). This study focused on the establishment of the main metabolic pathways involved in the muscle energy resynthesis during the competitions. Heart rate (HR) was recorded throughout the CC events. Jugular venous blood samples were withdrawn before the warm-up period, immediately after the competitions and at 5 and 10 min in the recuperation period. The following haematological parameters were studied: r...
Nath LC, Elliott AD, Weir J, Curl P, Rosanowski SM, Franklin S.Atrial fibrillation (AF) impacts performance and horse and jockey safety. Understanding the outcomes of AF identified postrace will better inform regulatory policy. Objective: To investigate the outcomes after episodes of AF identified postrace and determine whether affected horses are at increased risk of additional episodes compared to the general racing population. Methods: Total of 4684 Thoroughbred racehorses. Methods: Race records for Thoroughbred horses racing in Hong Kong from 2007 to 2017 were reviewed. Horses that performed below expectation were examined by cardiac auscultation and ...
Younes M, Robert C, Cottin F, Barrey E.Nearly 50% of the horses participating in endurance events are eliminated at a veterinary examination (a vet gate). Detecting unfit horses before a health problem occurs and treatment is required is a challenge for veterinarians but is essential for improving equine welfare. We hypothesized that it would be possible to detect unfit horses earlier in the event by measuring heart rate recovery variables. Hence, the objective of the present study was to compute logistic regressions of heart rate, cardiac recovery time and average speed data recorded at the previous vet gate (n-1) and thus predict...
Goodrich LR, Nixon AJ, Fubini SL, Ducharme NG, Fortier LA, Warnick LD, Ludders JW.To determine whether preoperative epidural administration of morphine and detomidine would decrease postoperative lameness after bilateral stifle arthroscopy in horses. Methods: Prospective clinical controlled study. Methods: Eight adult horses that had bilateral arthroscopic procedures, including drilling of cartilage and subchondral bone within the femoropatellar joints. Methods: Horses were randomly separated into 2 groups. Preoperatively, 4 horses were administered a combination of epidural morphine (0.2 mg/kg) and detomidine (30 microg/kg), and 4 horses were administered an equivalent vol...
Potter JJ, MacFarlane PD, Love EJ, Tremaine H, Taylor PM, Murrell JC.To compare sedative and analgesic properties of buprenorphine or morphine for standing procedures combined with a detomidine continuous rate infusion (CRI). Methods: Blinded, prospective, randomized clinical pilot study. Methods: Ten horses presented for dental or sinus procedures. Methods: Horses received 0.02 mg kg(-1) acepromazine intravenously (IV), followed 30 minutes later by detomidine 10 μg kg(-1) IV. Five minutes later, buprenorphine 0.01 mg kg(-1) (n = 6) or morphine 0.1 mg kg(-1) (n = 4) was administered IV. Detomidine was administered by CRI (0.2 μg kg(-1) minute(-1)) and adjuste...
O'Reilly J, Cheng HL, Poon ET.Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the "in-race" heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. "In-race" HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (le...
da Costa CF, Samesima N, Pastore CA.Different methodologies for electrocardiographic acquisition in horses have been used since the first ECG recordings in equines were reported early in the last century. This study aimed to determine the best ECG electrodes positioning method and the most reliable calculation of mean cardiac axis (MEA) in equines. Methods: We evaluated the electrocardiographic profile of 53 clinically healthy Thoroughbreds, 38 males and 15 females, with ages ranging 2-7 years old, all reared at the São Paulo Jockey Club, in Brazil. Two ECG tracings were recorded from each animal, one using the Dubois lead posi...
Driessen B, Nann L, Benton R, Boston R.To study whether hemodynamic function in horses, particularly mean arterial blood pressure (MAP), is better maintained with sevoflurane than isoflurane, thus requiring less pharmacological support. Methods: Prospective randomized clinical investigation. Animals Thirty-nine racehorses undergoing arthroscopy in lateral recumbency. Methods: Horses were assigned to receive either isoflurane (n = 20) or sevoflurane (n = 19) at 0.9-1.0 minimum alveolar concentration (MAC) for maintenance of anesthesia. Besides routine clinical monitoring, cardiac output (CO) was measured by lithium dilution. Hemodyn...
Persson SG.The purposes of this study were to elucidate the influences of age and sex on the heart rate (HR, bpm) and blood lactate (LA, mmol/l) related exercise tolerance parameters V2000 (tread ill velocity at HR 200), VLA4 (velocity at LA 4), W200 (power output at V2000), and WLA4 (power output at VLA4), and to establish reference values for these in normally performing Standardbred trotting race horses. A further aim was to improve the predictability of individual normal values by correlating them with the total red blood cell volume (CV) alone or in combination with the blood lactate response at V20...
Parviainen AK, Trim CM.This retrospective study was initiated to identify complications of anaesthesia occurring during ocular surgery. Records of 74 horses anaesthetised for eye enucleation, 65 horses anaesthetised for surgery of the eye and adnexa, and 51 horses anaesthetised for splint bone excision were reviewed. Fifty-three percent of the horses anaesthetised for eye enucleation moved during surgery which was significantly more frequent than in the other groups (P = 0.001). The incidence of moving was significantly reduced by use of an anaesthetic gas analyser for monitoring (P = 0.001). Transient hypertension ...
Couroucé A, Chrétien M, Valette JP.We hypothesised that the derived physiological variables V2 and V4 (velocity to achieve a blood lactate concentration of 2 and 4 mmol/l, respectively), HR2 and HR4 (the corresponding heart rate) and V200 (the velocity for a heart rate of 200 beats/min) would improve with training state and age, in French Trotters. A total of 194 French Trotters from one training establishment were followed for 6 years and 1105 standardised field exercise tests performed on a sand training track. The horses were divided into 6 age groups (from 1 to > or = 6 years) and 4 training groups (beginning, endurance tra...
Thomas DP, Fregin GF, Gerber NH, Ailes NB.The cardiorespiratory and metabolic responses to various levels of tethered-swimming were evaluated in 5 sedentary horses. Cardiac output (Q) and heart rate (HR) correlated highly (r = 0.89 and 0.94 respectively) with work effort (WE) expressed as kg pulled . kg body wt-1 . 10-2. While swimming, stroke volume (SV) was reduced at the lowest workloads, but increased with increasing WE so that at the highest workloads it had returned to the on-land standing SV. Pressures in the pulmonic as well as on both sides of the systemic circulation were considerably elevated by this form of exercise, altho...
Castanheira M, Paiva SR, Louvandini H, Landim A, Fiorvanti MC, Paludo GR, Dallago BS, McManus C.The environment in which the horse is reared affects its ability to maintain thermal balance which is in turn related to thermal characteristics and regulatory physiological mechanisms. In this study a multivariate analysis of physiological traits in relation to heat tolerance in horses was carried out in the Federal District, Brazil. The aim was to test the ability of these analyses to separate groups of animals and determine which physiological traits are most important in the adaptation to heat stress. Forty adult horses (4 to 13 years) were used, ten from each of four different genetic gro...
Greene SA, Thurmon JC, Tranquilli WJ, Benson GJ.Eight ponies were anesthetized with a solution containing 50 mg of guaifenesin, 1 mg of ketamine, and 0.5 mg of xylazine X ml-1 of 5% dextrose in water. Anesthesia was induced by IV injection (1.1 ml X kg-1), followed by continuous IV infusion at 2.75 ml X kg-1 X hr-1. Heart rate, rate-pressure product, mean pulmonary artery pressure, and standard bicarbonate were not significantly changed throughout the study. Systolic, diastolic, and mean arterial pressures and left ventricular stroke work index were significantly decreased at 5 and 15 minutes after a bolus of the anesthetic solution was inj...
Bukhari SSUH, Parkes RSV.About 112 million working equids are the source of income for 600 million people globally. Many equids are used for pulling loads (up to 15,000 kg per day) to transport goods. Most of them are associated with brick kilns, mining, and agriculture industries in developing countries. They may suffer from welfare issues such as overloading, being beaten, and being forced to work for long periods. These issues may occur due to a poor understanding of load-pulling equids. Understanding their capabilities and the elements that influence them is critical for efficient performance and welfare. The me...
Seo JP, Son WG, Gang S, Lee I.This study was performed to evaluate the sedative and analgesic effects of xylazine (X) and tramadol (T) intravenously (IV) administered to horses. Six thoroughbred saddle horses each received X (1.0 mg/kg), T (2.0 mg/kg), and a combination of XT (1.0 and 2.0 mg/kg, respectively) IV. Heart rate (HR), respiratory rate (RR), rectal temperature (RT), indirect arterial pressure (IAP), capillary refill time (CRT), sedation, and analgesia (using electrical stimulation and pinprick) were measured before and after drug administration. HR and RR significantly decreased from basal values with X and XT t...
Hawkins JF, Bowman KF, Roberts MC, Cowen P.Peritonitis was diagnosed in 67 horses between 1985 and 1990: 14 horses developed septic peritonitis after intestinal rupture, 25 horses developed peritonitis after abdominal surgery, and 28 horses had peritonitis not associated with intestinal rupture or abdominal surgery. Forty of 67 horses (59.7%) did not survive. Nonsurvivors had higher heart rates (P = 0.01), RBC count (P = 0.039), serum creatinine concentration (P = 0.036), PCV (P = 0.007), and anion gap (P = 0.005); lower venous blood pH (P = 0.002); and a greater number of bacterial species cultured from peritoneal fluid samples (P = 0...
Geor RJ, McCutcheon LJ, Ecker GL, Lindinger MI.The objective of this study is to determine the effects of heat, and heat and high relative humidity (RH) on the thermal and cardiorespiratory responses to exercise and recovery. Five Thoroughbred horses (age 3 to 6) completed exercise tests under each of 3 environmental conditions: cool, dry (CD, room temperature (T) = 20 degrees C, RH = 45-55%), hot, dry (HD, T = 32-34 degrees C, RH = 45-55%) and hot, humid (HH, T = 32-34 degrees C, RH = 80-85%). Horses were exercised at a workload equal to 50% of VO2max on a treadmill set at a 10% slope until attainment of a pulmonary artery blood (PA) temp...
Lebelt D, Zanella AJ, Unshelm J.The aim of the present study was to obtain information on the possible mechanisms underlying cribbing behaviour in horses. To investigate the horse's responsiveness to an external stimulus, a device for telemetric measurement of thermal threshold, using the forelimb withdrawal reflex, was developed and validated. Measurements of thermal threshold took place in cribbing horses (n = 11) before and during cribbing periods. Heart rate was monitored continuously in the same horses. Blood samples were collected before and during cribbing periods as well and in age- and sex-matched control horses (n ...
Ohmura H, Hiraga A, Aida H, Kuwahara M, Tsubone H, Jones JH.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...
Matthews NS, Hartsfield SM, Cornick JL, Williams JD, Beasley A.Six combinations of injectable anesthetic agents were administered to six adult horses in a Latin square design. The drug combinations were xylazine-ketamine, xylazine-butorphanol-ketamine, xylazine-tiletamine-zolazepam, xylazine-butorphanol-tiletamine-zolazepam, detomidine-ketamine, and detomidine-butorphanol-ketamine. Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial pH (pHa), PaCO2, PaO2, recumbency time, and number of attempts necessary to stand. Quality of induction and recovery, muscle relaxation, and response to stimulus were evaluated subjectively....
Radcliffe RM, Divers TJ, Fletcher DJ, Mohammed H, Kraus MS.To evaluate changes in plasma cardiac troponin I (cTnI) and L-lactate (LLt) as prognostic indicators in horses undergoing emergency abdominal surgery. Methods: Prospective observational study. Methods: Veterinary teaching hospital. Methods: Thirty-four horses undergoing emergency abdominal surgery. Methods: Serial blood sampling during various times during hospitalization (hospital admission, and 12, 24, 48, and 72 h postoperatively) evaluating cTnI and LLt concentrations. Results: All horses required surgery for correction of a strangulating (n = 29) or nonstrangulating obstruction (n = 5) of...
Gondim FJ, Zoppi CC, Pereira-da-Silva L, de Macedo DV.Maximal blood lactate steady state concentration (MLSS) and anaerobic threshold (AT) have been shown to accurately predict long distance events performance and training loads, as well, in human athletes. Horse endurance races can take up to 160 km and, in practice, coaches use the 4 mM blood lactate concentration, a human based fixed concentration to establish AT, to predict training loads to horse athletes, what can lead to misleading training loads. The lactate minimum speed (LMS) protocol that consists in an initial elevation in blood lactate level by a high intensity bout of exercise and t...
Eggensperger BH, Schwarzwald CC.To assess the influence of 2nd-degree AV blocks (AVB) on RR interval-based heart rate variability (HRV) variables; to investigate the effect of using PP interval time series and of artifact filtering on HRV analyses; to investigate the influence of electrocardiogram (ECG) recording length and time of recording; and to calculate day-to-day variability and reference intervals of HRV variables. Methods: Thirty healthy adult horses. Methods: RR and PP interval time series were extracted from 10-h Holter ECGs and an automated filter was applied to the RR time series (RR). Time-domain HRV variables...
Kaukinen H, Aspegrén J, Hyyppä S, Tamm L, Salonen JS.The objective of the study was to determine the absorption, bioavailability and sedative effect of detomidine administered to horses as an oromucosal gel compared to intravenous and intramuscular administration of detomidine injectable solution. The study was open and randomized, with three sequences crossover design. Nine healthy horses were given 40 μg/kg detomidine intravenously, intramuscularly or administered under the tongue with a 7-day wash-out period between treatments. Blood samples were collected before and after drug administration for the measurement of detomidine concentration...
Hubbell JA, Bednarski RM, Muir WW.The cardiopulmonary and anesthetic effects of xylazine in combination with a 1:1 mixture of tiletamine and zolazepam were determined in 6 horses. Each horse was given xylazine IV or IM, as well as tiletamine-zolazepam IV on 4 randomized occasions. Anesthetics were administered at the rate of 1.1 mg of xylazine/kg of body weight, IV, 1.1 mg of tiletamine-zolazepam/kg, IV (treatment 1); 1.1 mg of xylazine/kg, IV, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 2); 1.1 mg of xylazine/kg, IV, 2.2 mg of tiletamine-zolazepam/kg, IV (treatment 3); and 2.2 mg of xylazine/kg, IM, 1.65 mg of tiletamin...
Matthews NS, Peck KE, Mealey KL, Taylor TS, Ray AC.Five donkeys and three horses were given guaifenesin, intravenously, by gravity administration, until recumbency was produced. The time and dose required to produce recumbency, recovery time to sternal and standing were recorded. Blood samples were collected for guaifenesin assay at 10, 20, 30, 40, 50, 60 min, and 2, 3, 4 and 6 h after guaifenesin administration. Serum was analysed for guaifenesin using HPLC and pharmacokinetic values were calculated using a computer software package (RSTRIP). In donkeys, heart and respiratory rates and blood pressures were recorded before and at 5-min interva...
