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Topic:Anatomy
Anatomy in horses encompasses the study of the structural organization of the equine body, including the bones, muscles, organs, and systems that function together to sustain life and enable movement. Understanding equine anatomy is important for veterinarians, equine scientists, and horse owners, as it provides insights into how horses move, how they respond to external stimuli, and how various conditions can affect their health and performance. Key anatomical features in horses include the musculoskeletal system, which provides support and locomotion; the cardiovascular system, which circulates blood and nutrients; and the respiratory system, which facilitates gas exchange. This page compiles peer-reviewed research studies and scholarly articles that explore the detailed anatomy of horses, focusing on the structure and function of different body systems, their interrelationships, and their relevance to equine health, performance, and veterinary care.
Identification of normal parameters for ultrasonographic examination of the equine large colon and cecum. Six healthy horses were examined by using transabdominal ultrasonography, as described (1-3), to evaluate activity and size of the large colon and cecum at various locations. Using size and number of sacculations, activity patterns and contractile frequency; significant differences that would allow ultrasonographic identification of dorsal versus ventral colons, if they were displaced, were not found. The cecum had significantly greater activity than the colon, and a trend was seen towards smaller sacculations in the cecum than in the large colon. Six chevaux en santé ont été examinés par...
Expression and nephron segment-specific distribution of major renal aquaporins (AQP1-4) in Equus caballus, the domestic horse. Aquaporins (AQPs) play fundamental roles in water and osmolyte homeostasis by facilitating water and small solute movement across plasma membranes of epithelial, endothelial, and other tissues. AQP proteins are abundantly expressed in the mammalian kidney, where they have been shown to play essential roles in fluid balance and urine concentration. Thus far, the majority of studies on renal AQPs have been carried out in laboratory rodents and sheep; no data have been published on the expression of AQPs in kidneys of equines or other large mammals. The aim of this comparative study was to determ...
Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses. We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of masti...
Early lesions of osteochondrosis in the distal tibia of foals. Material available for research into osteochondrosis (OC) in humans tends to represent chronic lesions. Comparative studies of early lesions in young animals are, therefore, important in clarifying the pathogenesis of OC in humans. Recent studies in pigs provide strong evidence that lesions of articular OC are associated with a focal failure in the cartilage canal vascular supply to epiphyseal growth cartilage (articular-epiphyseal cartilage complex excluding the articular cartilage). The purpose of the present study was to examine histological sections from a specific predilection site for ar...
Movement between the equine ilium and sacrum: in vivo and in vitro studies. Sacroiliac disease (SID) is an important cause of loss of performance in horses, yet little is known about the biomechanics of movement of the sacroiliac joint (SIJ). Objective: (a) To document the presence of equine SIJ motion by measuring the change in cross-sectional area (CSA) of the dorsal portion of the dorsal sacroiliac ligament (DSIL) during application of manual forces to the pelvis, and to ascertain if this varied between horses with SID and normal horses; (b) To determine the amount and direction of motion available at the equine SIJ using 3-D orientation sensors, and how motion is ...
Functional anatomy of the caudal thoracolumbar and lumbosacral spine in the horse. Research in spinal biomechanics and functional anatomy has advanced back pain research in man. Yet, despite the performance limiting nature of back pain in horses, there are few data for the equine spine. Objective: To describe aspects of functional anatomy of the equine thoracolumbar and lumbosacral (LS) spine and potential effects on performance. Methods: The first study investigated variations in LS vertebral formula by post mortem examination of 120 horses. Midline vertebral transection was carried out on 65 Thoroughbred (TB), 24 Standardbred (SB) and 31 other breeds. The second study inve...
Abnormal radiographic findings in 865 French standardbred trotters and their relationship to racing performance. Developmental orthopaedic lesions are commonly found in French Standardbred horses. One of the main questions asked by trainers, owners and veterinarians is what impact these lesions have on the racing career and racing performances of horses. Objective: To study the prevalence and distribution of developmental orthopaedic lesions in young French Standardbred trotters and to relate them to racing performance. Methods: Feet, fetlock, tarsus and stifle regions were radiographed in 865 two-year-old French Standardbred trotters. Abnormal radiographic findings (ARF) were evaluated for 12 anatomical...
Ultrasonographic anatomy of the temporomandibular joint in healthy pure-bred Spanish horses. The objective was to describe the normal ultrasonographic appearance of the soft tissue and bony structures of the temporomandibular joint in Pure-Bred Spanish horses using frozen and plastinated sections performed as anatomical references. The temporomandibular joint of five healthy Pure-Bred Spanish horses and the head specimens from 12 Pure-Bred Spanish cadavers that were subjected to euthanasia for reasons other than temporomandibular joint problems were studied sonographically and anatomically. An 11 MHz linear-array transducer was used to obtain longitudinal ultrasonographic images of th...
Asymmetric signal intensity in normal collateral ligaments of the distal interphalangeal joint in horses with a low-field MRI system due to the magic angle effect. Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo TI, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The si...
Common atrioventricular canal in a newborn foal–case report and review of the literature. This paper presents the embryological and pathological features as well as the terminology and classification of common atrioventricular canal, a type of endocardial cushion defect. The authors give a complete description of an extremely rare congenital cardiac malformation in an equine neonate. The diagnosis of a complete, balanced common atrioventricular canal of type C in Rastelli's classification scheme was based on two-dimensional, contrast and colour Doppler echocardiography and subsequent postmortem gross pathology. To support our diagnosis and study the pathophysiological effect of the...
Alteration of distal tarsal subchondral bone thickness pattern in horses with tarsal pain. Understanding of the development of pathology and source of pain in distal tarsal osteoarthritis is poorly understood. Magnetic resonance imaging is often used in the analysis of human osteoarthritis (OA) because it is sensitive to early changes. Objective: In association with distal tarsal joint (DTJ) pain, there will be an alteration in the characteristic subchondral bone (SCB) thickness pattern of horses with no history of pain when subjected to low-level exercise. Methods: Sixteen cadaver tarsal joints were collected from 9 mature horses with a history of tarsal pain and radiographic evide...
Expression of connexin 43 protein in testes, epididymides and prostates of stallions. Connexin 43 (Cx43) is a ubiquitously distributed gap junction protein in testes and other reproductive tissues. Adjacent cells share ions and small metabolites through intercellular channels, which are present in gap junctions. Previously, Cx43 has not been reported in testes, epididymides and prostates either in healthy stallions or cryptorchid horses. Objective: To demonstrate the expression pattern of Cx43 in the reproductive tissues of stallions and examine whether naturally occurring bilateral cryptorchidism has any influence on distribution and expression of Cx43. Methods: The expression...
Equine pericardium for dural grafts: clinical results in 200 patients. Serous sheets are currently used in Neurosurgery as dural substitute. The aim of this study is to demonstrate that the horse pericardium, which has the essential charasteristics of reabsorbable membranes and moreover is BSE-free, is an excellent dural substitute. Methods: 200 patients, 53 suffering from cranial traumatic conditions and 97 from cranial and craniospinal neoplastic pathologies, underwent a surgical procedure with the application of horse pericardium as a dural prosthesis. Results: The follow-up controls of the patients included a neurosurgical visit and advanced diagnostic imagin...
The distribution of ganglion cells in the equine retina and its relationship to skull morphology. It has recently been reported that a strong correlation exists between the distribution of retinal ganglion cells and nose length in the domestic dog. To determine if this phenomenon occurs in another domestic species with diverse skull morphology, the current study examined the distribution of retinal ganglion cells in 30 horses from a variety of breeds. There was a significant variation in the density of ganglion cells found across the retinae. Breed was a significant predictor for ganglion cell density within the visual streak. A strong positive correlation exists between the density of gan...
3D kinematics of the interphalangeal joints in the forelimb of walking and trotting horses. The objective was to measure 3D rotations of the distal (DIP) and proximal (PIP) interphalangeal joints at walk and trot. 3D trajectories of markers fixed to the proximal phalanx, middle phalanx and the hoof wall of the right forelimb of four sound horses were recorded at 120 Hz. Joint kinematics were calculated in terms of anatomically-based joint coordinate systems between the bone segments. Ranges of motion were similar at walk and trot. Values for the DIP joint were: flexion/extension: 46 +/- 3 degrees at walk, 47 +/- 4 degrees at trot; internal/external rotation: 5 +/- 1 degrees at walk, ...
Equine gastric ulcer syndrome in adult horses: a review. In recent years, gastric ulceration has been recognised as a common, possibly performance-limiting disease of adult horses. Here, we aim to provide the reader with a useful review of recent literature covering all aspects of equine gastric ulcer syndrome (EGUS) in adult horses. The anatomy and physiology of the stomach, with particular reference to secretion of acid and mucosal protective mechanisms, are reviewed, as are the differing theories relating to the aetiopathogenesis of gastric ulceration. We also explore the possible influence of various management factors on development of the dise...
Ultrasonographic evaluation of the supraspinous ligament in a series of ridden and unridden horses and horses with unrelated back pathology. Injury to the supraspinous ligament (SSL) is reported to cause back pain in the horse. The diagnosis is based on clinical examination and confirmed by ultrasonographic examination. The ultrasonographic appearance of the supraspinous ligament has been well described, but there are few studies that correlate ultrasonographic findings with clinical pain and/or pathology. This preliminary study aims to test the hypothesis that unridden horses (n = 13) have a significantly reduced frequency of occurrence of ultrasonographic changes of the SSL consistent with a diagnosis of desmitis when compared to...
Histologic effect of semiconductor diode laser transscleral cyclophotocoagulation on the normal equine eye. To determine the acute histologic effects of semiconductor diode laser transscleral cyclophotocoagulation (TSCP) on the normal equine eye. Methods: Part 1: eight eyes of four horses. Part 2: 10 eyes of five horses. Methods: Part 1: TSCP was performed on four eyes at 4 mm and four eyes at 6 mm posterior to the limbus with 15 sites treated in four quadrants at 1800 mW for 1500 ms. The globes were sectioned transversely or sagitally to examine all quadrants and histologic sections were taken every 1 mm for the entire globe. Part 2: Based on the results from Part 1, TSCP was performed at 20 sites ...
Radiographic evaluation of tooth drift after cheek tooth extraction and insertion of an intra-alveolar prosthesis in ponies. The aim of the study was to investigate post-extraction tooth drift in ponies and the influence of an intra-alveolar prosthesis. The maxillary 08 was bilaterally repulsed in five ponies under general anaesthesia. On one side the alveolus was left to granulate, and on the other a synthetic bone substitute prosthesis was fitted. Standard radiographic projections of the head were taken monthly during the first year and at 24 months post-operatively. Different cephalometric parameters were measured and statistically analyzed. Rostral and caudal drift were recognized in molar and premolar teeth, re...
Differentiating human bone from animal bone: a review of histological methods. This review brings together a complex and extensive literature to address the question of whether it is possible to distinguish human from nonhuman bone using the histological appearance of cortical bone. The mammalian species included are rat, hare, badger, racoon dog, cat, dog, pig, cow, goat, sheep, deer, horse, water buffalo, bear, nonhuman primates, and human and are therefore not exhaustive, but cover those mammals that may contribute to a North American or Eurasian forensic assemblage. The review has demonstrated that differentiation of human from certain nonhuman species is possible, i...
Colonic ganglioneuromatosis in a horse. Ganglioneuromas are complex tumors that arise in peripheral ganglia and are composed of well-differentiated neurons, nerve processes, Schwann cells, and enteric glial cells. The term ganglioneuromatosis (GN) denotes a regional or segmental proliferation of ganglioneuromatous tissue. This report describes an 8-year-old mixed breed horse with GN in a 25-cm segment of small colon. Grossly, the lesion consisted of numerous sessile to pedunculated nodules extending from the serosal surface. Histologic examination revealed the nodules to consist of fascicles of spindle-shaped cells consistent with S...
First description of the horse stomach worm, Habronema muscae (Spirurida: Habronematidae) by scanning electron microscopy. Habronema muscae (Spirurida: Habronematidae) occurs in the stomach of equids, is transmitted by adult muscid dipterans and causes gastric habronemiasis. Scanning electron microscopy (SEM) was used to study the morphological aspects of adult worms of this nematode in detail. The worms possess two trilobed lateral lips. The buccal cavity was cylindrical, with thick walls and without teeth. Around the mouth, four submedian cephalic papillae and two amphids were seen. A pair of lateral cervical papillae was present. There was a single lateral ala and in the female the vulva was situated in the mid...
Instrumented anterior lumbar interbody fusion with equine bone protein extract. Randomized and self-controlled study with anterior lumbar interbody fusion in a porcine model. Objective: To determine the osteoinductive potential of an equine bone protein extract in anterior interbody spinal fusion. Background: Interbody spinal fusion with bone graft transplantation is a common spine procedure. Complications related to bone graft harvesting are still a major concern. Equine demineralized bone matrix has been reported to be osteoinductive. However, the application of equine bone protein extract in spine fusion has not been documented. In this experiment, we evaluated equine ...
Comparative anatomy of the meniscofemoral ligament in humans and some domestic mammals. The purpose of this study was to investigate the presence, position and relative sizes of the meniscofemoral ligaments (MFL) in three quadrupeds and humans and relate these to the caudal slope of the lateral tibial plateau. Canine, ovine and equine stifles and human knees were dissected to identify the presence of MFLs, their obliquity in relation to the caudal cruciate ligaments (CCL), the relative size and shape of the MFLs compared with the CCL, the points of femoral attachment of the MFLs and CCL, and the distance between the MFLs and CCL at their midpoints. The lateral tibial condyle was ...
Ultrasound-assisted collection of cerebrospinal fluid from the lumbosacral space in equids. To describe ultrasonographic landmarks for use in collection of CSF from the lumbosacral region in equids. Methods: Prospective study. Methods: 37 equids (27 with neurologic disease and 10 with nonneurologic disease). Methods: Standing equids (n = 17) were sedated with detomidine hydrochloride (0.006 to 0.01 mg/kg [0.003 to 0.005 mg/lb], IV) followed by butorphanol tartrate (0.01 mg/kg, IV) and restrained with a nose twitch for collection of CSF. The CSF was collected from 20 laterally recumbent equids (10 sedated and 10 immediately after euthanasia). Anatomic landmarks were identified ultraso...
Sensitivity of an equine distal limb model to perturbations in tendon paths, origins and insertions. As equine musculoskeletal models become common, it is important to determine their sensitivity to the simplifications used. A subject-specific distal forelimb model was created using bones extracted from CT scans to examine movement from in-vivo invasive-marker motion capture. The movements of the sesamoid bones were simulated using the constraints of maintaining an isometric virtual ligament and maintaining contact between the appropriate articular surfaces, creating a variable moment arm for the tendons. The simulation of the proximal sesamoid bones was compared to movement recorded in-vitro...
Scintigraphic evaluation of the proximal metacarpal and metatarsal regions of horses with proximal suspensory desmitis. The aim of the study was to characterize radiopharmaceutical uptake patterns in horses with clinical and ultrasonographic evidence of proximal suspensory desmitis. It was hypothesized that radiopharmaceutical uptake in the proximal palmar (plantar) aspect of the third metacarpal (metatarsal) bone would be greater in lame limbs of horses with proximal suspensory desmitis than in sound limbs and that there would be a positive correlation between the severity of ultrasonographic abnormalities and the degree of radiopharmaceutical uptake. Nuclear scintigraphic evaluation of the proximal metacarpal...
