The equine cardiovascular system, particularly the heart, is fundamental to maintaining the health and performance of horses. The heart is responsible for pumping oxygenated blood throughout the body, supporting vital functions and physical activity. In horses, the heart's structure and function are adapted to meet the demands of both rest and exertion, with notable features such as a large cardiac output and efficient blood circulation. Conditions affecting the equine heart, such as arrhythmias, valvular diseases, and myocardial disorders, can significantly impact a horse's well-being and athletic capability. This page aggregates peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and pathophysiology of the equine heart, as well as diagnostic and therapeutic approaches to managing cardiac health in horses.
Holmes JR, Alps BJ.The paper describes observations on the distributions of the P, QRS and T cardiac vectors in the horizontal plane, comparing healthy horses with those with arrhythmia and cardiac murmurs. Deviation of the T vector from the normal range appeared to occur most commonly in association with cardiac murmurs, particularly those involving the semilunar valves and aorta.
Holmes JR, Alps BJ.The paper describes observations on the distributions of the P, QRS and T cardiac vectors in the horizontal plane in 377 apparently healthy horses. The possible usefulness of vectorcardiography in the clinical evaluation of cardiac function is briefly discussed.
Misdorp W.A pathological study of 333 tumours of farm animals in the Netherlands is presented. Most of the tumours (224) were collected at the Amsterdam abattoir over a period of five consecutive years. The incidence of different types of the tumours is compared with figures compiled in the U.S.A. Tumours in cattle and pigs were less frequent in the Amsterdam material than in the U.S.A., but the incidence in horses and sheep was higher than reported elsewhere. Tumours of the jejunum, the ovaries and to a lesser extent of the heart were more frequent, but those of the skin and male genital organs were le...
Holmes JR, Alps BJ.Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed.
Marcus LC, Ross JN.The hearts of 23 aged equids (18 horses and 5 mules) were examined histologically. Major findings included arteriolosclerosis and intimal bodies in small muscular arteries, myocarditis, myocardial fibrosis, fatty metamorphosis of myocardial and Purkinje fibers, myocytolysis, and basophilic (mucinous) degeneration of myocardium. Lesions less frequently seen included chronic fibrotic valvulitis, acute myocardial necrosis, sarcosporidiosis, and hemosiderosis. Single cases of malignant melanoma, cartilaginous metaplasia of the I-V septum, mineralization of connective tissue in the I-V septum, and ...
Decloedt A, Broux B, De Clercq D, Deprez P, Van Steenkiste G, Vera L, Ven S, van Loon G.Based on its pharmacokinetic profile and electrophysiological effects in healthy horses, sotalol potentially could be used as a long-term PO antiarrhythmic drug in horses. Objective: To evaluate the effect of sotalol on heart rate (HR), QT interval, atrial fibrillatory rate, and success of cardioversion in horses with naturally occurring chronic atrial fibrillation (AF). Methods: Twenty-eight horses referred for transvenous electrical cardioversion of AF were treated with 2 mg/kg sotalol PO q12h for 3 days before cardioversion, and 13 horses underwent the same protocol without sotalol administ...
Piketh G, Williams A, Schliewert EC.Electrocardiography is the method used to monitor the electrical impulses in the heart. These diagnostics are increasingly making use of smartphone-based technologies. The objective of this research was to determine whether the Alivecor KardiaMobile (ECG) smartphone-modulated electrocardiographic device, a novel ECG device, can be used to obtain reliable electrocardiogram (ECG) readings in horses. The device was initially tested in 36 Nooitgedacht pony mares to determine the best site of application, method of skin preparation, and ECG device orientation for reliable ECG tracings. Once the mos...
Marr CM.Respiratory and cardiac diseases are common in older horses. Advancing age is a specific risk factor for cardiac murmurs and these are more likely in males and small horses. Airway inflammation is the most common respiratory diagnosis. Recurrent airway obstruction can lead to irreversible structural change and bronchiectasis; with chronic hypoxia, right heart dysfunction and failure can develop. Valvular heart disease most often affects the aortic and/or the mitral valve. Management of comorbidity is an essential element of the therapeutic approach to cardiac and respiratory disease in older e...
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.
Huesler IM, Mitchell KJ, Schwarzwald CC.Echocardiographic assessment of left atrial (LA) size and function in horses is not standardized. Objective: The aim of this study was to establish reference intervals for echocardiographic indices of LA size and function in Warmblood horses and to provide proof of concept for allometric scaling of variables and for the clinical use of area-based indices. Methods: Thirty-one healthy Warmblood horses and 91 Warmblood horses with a primary diagnosis of mitral regurgitation (MR) or aortic regurgitation (AR). Methods: Retrospective study. Echocardiographic indices of LA size and function were meas...
Valentín-Rodríguez C, López-Garriga J, Torres-Lugo M.Proteins are biological macromolecules which have a unique spatial conformation. Once this 3D spatial conformation is affected the protein's biological stability and activity can be severely limited. For these reasons, this investigation focuses on the effects of pre-polymeric solution components on the behavior of proteins to be encapsulated by the entrapment technique in anionic, cationic, and neutral hydrogel membranes. Equine skeletal muscle myoglobin (MMb), and equine heart myoglobin (HMb) were employed as model molecules. Three hydrogel morphologies were examined: methacrylic acid-poly(e...
Ruíz-López P, Cuypers C, Schauvliege S.This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg...
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...
Burger D, Vidondo B, Gerber V, Deillon D, Müller A, Scheidegger M, Käser R, Ramseyer A.Fatigue and related injuries to the musculoskeletal system are among the most frequent reasons for the withdrawal of high-level eventing horses from the sport. The safety of both horse and rider is very important, and early detection of fatigue is crucial. Objective: To investigate elite eventing horses in competitive events focusing on biomechanical, cardiovascular and metabolic variables across the cross-country test and to identify their potential associations with fatigue. Methods: Prospective observational exploratory field study. Methods: Observations on 54 cross-country tests of 33 hors...
The study aimed to assess Apgar scores and collect data on clinical, hemato-biochemical, and venous blood gas parameters in seven mules during their first 48 hours of life. Apgar scores, heart rate (HR), respiratory rate (RR), body temperature (BT), body weight (BW), time to achieve sternal recumbency, stand, nurse, and pass meconium were recorded. Blood samples were collected at birth (T0), 6 (T6), 12 (T12), 24 (T24), 48 (T48) hours of life. Data distribution was verified and differences in laboratory parameters over time assessed. One foal had an Apgar score of 6/8, thus excluded from the st...
Fritz SA, Hall JO.Ionophores are a class of polyether antibiotics that are commonly used as anticoccidial agents and growth promotants in ruminant diets. Ionophores transport ions across lipid membranes and down concentration gradients, which results in mitochondrial destruction, reduced cellular energy production, and ultimately cell death. Cardiomyocytes are the primary target in equine patients when exposed to toxic concentrations and the clinical disease syndrome is related to myocardial damage. Animals can survive acute exposures but can have permanent heart damage that may result in acute death at future ...
Poochipakorn C, Wonghanchao T, Huangsaksri O, Sanigavatee K, Joongpan W, Tongsangiam P, Charoenchanikran P, Chanda M.During an African horse sickness (AHS) outbreak, horses were able to exercise daily in a net-covered arena, yet the physiological responses to exercise in a netted arena was unknown. In a cross-over study design, eight horses performed a 39-minute aerobic exercise in conventional (CA) and vector-protected arenas (VPA). Horses were slower in some gaits and covered less distance in the VPA arena (P < .01). Cortisol release, hematology, and heart rate variability (HRV) were also examined. An interaction between the riding arena and time was observed in hematocrit (P = .0013), hemoglobin (P = ...
Hajimohammadi A, Ghane M, Ghari Tehrani M, Paravar B, Mirzaei A, Razavi S, Nikzad M.Sixty-one horses were enrolled in this study and divided into 3 different groups according to their severity of colic (heart rate, oral mucous membrane color, and abdominal distention): a strangulating colic (SC) group (n=21), non-strangulating colic (NC) group (n=20), and control group (n=20) consisting of randomly selected normal horses without signs of colic. The serum concentrations of haptoglobin, tumor necrosis factor-α (TNFα), nitric oxide (NO), malondialdehyde (MDA), zinc, iron, and copper were evaluated in all horses. The average concentration of TNFα in the SC group was higher tha...
Flood J, Byrne D, Bauquier J, Agne GF, Wise JC, Medina-Torres CE, Wood K, Sullivan O, Stewart AJ.Right dorsal colitis (RDC) is a nonsteroidal anti-inflammatory drug (NSAID) induced, protein losing enteropathy in horses associated with a high case fatality rate. Objective: To describe signalment, NSAID usage, clinical presentations, clinical pathology, ultrasonographic findings, treatments, outcomes, and factors associated with survival in horses diagnosed with RDC. Methods: Thirty-five horses from 7 Australian equine hospitals diagnosed with RDC. Methods: Retrospective case series. Clinical records of cases were accepted if definitively or presumptively diagnosed by an internist with RDC ...
Schmidt TE, Gleason CB, Samaniego MR, White RR.Failure to properly prepare the equine athlete for exercise and support post-exercise recovery is a contributing factor to physical breakdown and lameness. Equine physiotherapy was not introduced until the early twentieth century and has since evolved to allow for wearable therapies such as therapeutic boots to be accessible to a broad spectrum of equestrians. The purpose of this study was to evaluate the effects of ceramic boots, boots combining vibration and cryotherapy, and boots containing tourmaline on the performance of sport horses during jumping as well as to examine changes in vital s...
Quattrini C, Bozorgmanesh R, Egli P, Magdesian KG.Fecal microbiota transplant (FMT) is increasingly administered as part of the treatment of colitis in horses, yet there is little data as to its effectiveness. Retrospective evaluation of the effects of FMT on discharge status, fecal consistency, length of hospitalization, and improvement in clinical signs in horses hospitalized for diarrhea. Retrospective case-control study. Medical records of adult horses (>1 year old) that received at least one transfaunation treatment (2013-2018) in two referral hospitals were identified through a medical records database search. Medical records of contemp...
Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ.The hormones insulin and adiponectin are commonly measured in equids because of their involvement in endocrinopathic laminitis. These are currently measured in serum/plasma, although jugular venipuncture can cause stress in some animals and may be impossible in needle-shy individuals. However, both hormones can be measured in saliva in other species. Objective: To determine whether [insulin] and [total adiponectin] are detectable in equine saliva using automated assays and whether saliva collection is associated with changes in stress indicators. Additionally, the correlation between serum and...
Massie SL, Bezugley RJ, McDonald KJ, Léguillette R.Arrhythmias are commonly reported in exercising horses, however due to regulatory constraints electrocardiograms (ECGs) are acquired during training but not competition, raising questions about the repeatability of findings. The aims were (1) compare training and competition arrhythmias and (2) describe the repeatability of arrhythmias during maximal-intensity exercise. A convenience sample of 52 healthy Thoroughbreds (aged 8.7 ± 2.5 years) competing in the World Professional Chuckwagon Association were obtained, totaling 152 training or competition ECGs (2-7 ECGs/horse). Speed, heart rate ...
Katz LM, Gough K, McGivney CL, McGivney B, Sides RH, Hill EW, Bayly WM.Sex effects on ventilatory and oxygen consumption (V̇O) measurements during exercise have been identified in humans. This study's aim was to evaluate the hypothesis that there are sex effects on ventilatory and V̇O measurements in exercising, untrained yearling Thoroughbreds (Tb). Forty-one Tbs (16 colts, 25 fillies; 19.8 ± 1.4 months old) were recruited. Physiological, ventilatory and exercise data were gathered from horses exercising unridden at high intensity on an all-weather track from a global positioning-heart rate unit and a portable ergospirometry system. Data were analysed with an...
Bindi F, Vezzosi T, Sala G, Freccero F, Marmorini P, Bonelli F, Sgorbini M.Smartphone-based technology for ECG recording has recently spread as a complementary tool for electrocardiographic screening and monitoring in adult horses and in other animal species. The present study aimed to assess the feasibility and accuracy of a smartphone-based ECG in healthy foals. This was a prospective observational study (authorization n. 45,865/2016) including 22 foals aged less than 21 days. A reference standard base-apex ECG (rECG) was acquired, and a smartphone ECG (sECG) was recorded immediately after by using a smartphone-based single lead electrocardiograph. All ECG tracings...
Diaz AEC, Herfindal L, Andersen HL, Fossen T.Parsley fern, , is a common fern in arctic-alpine regions, and even though this species has been known since ancient times and has been presumed to cause the poisoning of horses, its natural products have not previously been investigated. Here, we characterise 15 natural products isolated from the aerial parts of , including the previously undescribed compound 3-malonyl pteroside D. The structure determinations were based on several advanced 1D and 2D NMR spectroscopic techniques, Circular Dichroism spectroscopy and high-resolution mass spectrometry. The pteroside derivatives exhibited selecti...
Gruber N, Gesell-May S, Scholler D, Zablotski Y, May A.Equine colic is an important condition associated with acute abdominal pain and one of the leading causes of death in horses. As such, objectively evaluating pain is of interest for attending veterinarians. Pain scales for assessment are present, but no single pain-specific biomarker has been reported. The aim of this study was to determine if substance P (SP) could be a reliable biomarker to reflect pain and serve as a parameter to predict outcome in equine colic. The hypothesis was that horses displaying severe colic signs present with higher values of SP in contrast to those with mild colic...
Vernemmen I, Van Steenkiste G, Hauspie S, De Lange L, Buschmann E, Schauvliege S, Van den Broeck W, Decloedt A, Vanderperren K, van Loon G.Insight into the three-dimensional (3D) anatomy of the equine heart is essential in veterinary education and to develop minimally invasive intracardiac procedures. The aim was to create a 3D computer model simulating the in vivo anatomy of the adult equine heart. Methods: Ten horses and five ponies. Methods: Ten horses, euthanized for non-cardiovascular reasons, were used for in situ cardiac casting with polyurethane foam and subsequent computed tomography (CT) of the excised heart. In five anaesthetized ponies, a contrast-enhanced electrocardiogram-gated CT protocol was optimized to image th...
Hallman I, Tapio H, Raekallio M, Karikoski N.To assess the effects of an α-adrenoceptor agonist (detomidine) constant rate infusion (CRI) with and without an α-adrenoceptor antagonist (vatinoxan) CRI on blood insulin and glucose concentrations, heart rate, intestinal borborygmi, and sedation during and after infusion in horses. Methods: Randomized, blinded, crossover, experimental study. Methods: A total of nine healthy, adult Finnhorse mares. Methods: Horses were treated with an intravenous (IV) detomidine loading dose (0.01 mg kg), followed by CRI (0.015 mg kg hour), and the same doses of detomidine combined with an IV vatinoxan load...
Eichler F, Ehrle A, Jensen KC, Baudisch N, Petersen H, Bäumer W, Lischer C, Wiegard M.Cannabidiol (CBD) products have been proposed to exert stress- and anxiety-relieving effects in animals. Despite the increasing popularity of CBD for veterinary use, the available research detailing the effects of CBD in horses is limited. The aim of this study (part 1 of 2) was to analyze stress parameters via behavioral observations and heart rate monitoring in healthy horses following single oral administration of a CBD containing paste in different doses. Study products were two pastes for oral administration, one containing CBD and one containing no active ingredient. Pastes were applied ...
Dufourni A, Buschmann E, Vernemmen I, Van Steenkiste G, van Loon G, Decloedt A.Echocardiographic measurements are important prognostic indicators but might be influenced by heart rate and blood pressure. This is particularly important when comparing repeated examinations. Objective: To determine the effect of physiological stress at mildly increased heart rates and pharmacological challenge using IV administration of N-butylscopolammonium bromide and metamizol sodium on heart rate, blood pressure, and echocardiographic measurements. Methods: Twenty healthy Warmblood horses. Methods: Randomized crossover study. Horses were examined echocardiographically by 2-dimensional, ...
Lorello O, Rule E, Haughan J, Wang K, Niu M, Brown K, Navas de Solis C.Equine veterinarians performing chiropractic treatments are frequently asked to evaluate and treat sound horses to improve their performance and address pain associated with the axial skeleton. Studies describing the effects and mechanisms of chiropractic treatments in horses without overt lameness are scarce. Objective: This study aimed to evaluate the effect of chiropractic treatments on stride rate, length, symmetry, heart rate and rider-perceived quality of the ridden work in sport horses. Methods: A blind randomised controlled trial with crossover design. Methods: Thirty-eight horses ridd...
Ferlini Agne G, Kapusniak AE, Wooldridge AA, Jung SW.In this case report, a high dose of torsemide (6mg/kg, every 12 hours for 3 days followed by 12mg/kg, every 12 hours for 4 days) was administered orally to a horse with congestive heart failure (CHF) and atrial fibrillation. Blood samples for measurement of plasma torsemide concentrations were obtained one hour after each drug administration. Pharmacodynamic effects of oral torsemide were evaluated by daily physical examination, electrocardiography, and serum biochemistry. The horse tolerated administration of torsemide. A decrease in ventral oedema and venous congestion was subjectively noted...
Eichler F, Ehrle A, Machnik M, Jensen KC, Wagner S, Baudisch N, Bolk J, Pötzsch M, Thevis M, Bäumer W, Lischer C, Wiegard M.As a remedy against stress and anxiety, cannabidiol (CBD) products are of increasing interest in veterinary medicine. Limited data is available describing the actual effectiveness of CBD in horses. The aim of this study (part 2 of 2) was to analyze stress parameters via behavioral observation, heart rate monitoring and assessment of blood and saliva cortisol levels in healthy horses treated repeatedly with a CBD containing paste. Twelve horses were randomly assigned to a treatment or a control group. Two pastes were orally administered in a double-blinded study design, one paste containing CBD...
Kutara K, Kadekaru S, Hisaeda K, Sugimoto K, Ono T, Inoue Y, Nakamura S, Yoshitake R, Ohzawa E, Goto A, Iwata E, Shibano K, Une Y, Kitagawa H.The necropsy of a 2-day-old Noma horse that died of weakness showed an enlarged cardiac base and a narrow cardiac apex, suggesting cardiac malformation. The excised heart underwent imaging to investigate its luminal structure. On three-dimensional magnetic resonance imaging, the right atrium and right ventricle were discontinuous. The right atrium communicated with the left atrium and the left ventricle communicated with the right ventricle. The lumen narrowed near the pulmonary artery valve. Since the same findings were observed on gross examination, the foal was diagnosed with tricuspid atre...
