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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.
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...
Reliability of conformational measurements in the horse using a three-dimensional motion analysis system. The importance of a reliable method for conformation studies is generally acknowledged, but there are only limited data on the accuracy and precision of current assessment methods. Objective: To assess (1) the accuracy and repeatability of marker placement, (2) influence of stance of the horse on conformational parameters, (3) practicality of a computerised motion analysis system and (4) to compare the computerised motion analysis system to photographic systems of assessment. Methods: Twenty-eight reflective markers placed over anatomical landmarks were located in 3D using a computerised motio...
Ultrasound-guided coxofemoral arthrocentesis in horses. Coxofemoral joint pain is probably underestimated due to difficulties in identifying hip pain. The deep location of the joint and proximity of the sciatic nerve make arthrocentesis based on external landmarks a difficult and potentially risky procedure in mature horses. Objective: To describe an ultrasound-guided injection technique of the coxofemoral joint in standing horses and to evaluate its accuracy and potential difficulties/complications. Methods: Nine mature horses had both pelvic areas prepared for sterile ultrasound examination (3.5 MHz curvilinear probe). Coxofemoral joints were loc...
Developmental aspects of distal limb conformation in the horse: the potential consequences of uneven feet in foals. Distal limb conformation is generally accepted to be an important item with respect to performance and soundness in mature horses, but little is known about the developmental aspects. Objective: To gain insight into the development of distal limb conformation and to assess the possible consequences of uneven feet in foals. Methods: Conformation of the distal front limbs of 23 Warmblood foals was scored visually and measured using radiographs, at ages 27 and 55 weeks. At the same ages, pressure measurements were made under both front feet. Results: At both ages the hoof-pastern axis was broken-...
Muscle architecture of biceps brachii, triceps brachii and supraspinatus in the horse. Three muscles from the proximal equine forelimb were dissected in order to investigate their potential to contribute to proximal limb mechanics. Muscle mass, fibre length, tendon mass and tendon length were measured from biceps brachii, triceps brachii, supraspinatus and lacertus fibrosus (biceps lateral head mass 171-343.4 g and fibre length 0.5-0.8 cm; biceps medial head mass 283-500 g and fibre length 2.2-4 cm; biceps tendon mass 121.8-260 g and tendon length 35-44 cm; triceps long head mass 3200-6663 g and fibre length 19-26.3 cm; triceps lateral head mass 513.8-1240 g and fibre length 17....
Innervation and nerve injections of the lumbar spine of the horse: a cadaveric study. The distal limb innervation of the horse has been studied extensively to allow use of local anaesthetic techniques to detect the origin of pain in lameness. However, the innervation of the lumbar spine has so far been poorly described and a more precise description may assist clinicians to localise back pain in the horse. Objective: To gain better knowledge of the innervation of the lumbar spine and identify salient anatomical features that might be used for diagnostic and therapeutic ultrasound guided injections. Methods: The spines of 8 mature horses were dissected. Branches of the dorsal ra...
An anatomic study of the calcaneal bursae in the horse. To establish an injection site for the gastrocnemius calcaneal bursa (GCB), to identify communication patterns between the calcaneal bursae, to estimate the proximal and distal extents of the intertendinous calcaneal bursa (ICB) and to identify variations from previous anatomic descriptions. Methods: Descriptive anatomic study. Methods: Cadaveric equine hindlimbs (n=18) from 9 adult horses. Methods: Communication between the ICB and GCB was determined in 18 cadaveric hindlimbs by injection of a latex mixture, followed by examination of sequential sagittal sections and documentation of the dist...
A case of equine motor neuron disease (EMND). We report a case of EMND in a heavy horse that was bred and trained in Hokkaido, Japan. Clinical symptoms included severe ataxia of all four limbs, tilted head, lethargy, and flaccid lips. Numerous axonal degenerations and swellings were observed in nuclei, mostly in the cerebellar dentate nucleus and the nucleus of the hypoglossal nerve, and in the ventral horn of the spinal cord. In the ventral horn of the spinal cord, neuronal degeneration, swelling, and/or necrosis were observed sporadically. The case was diagnosed as EMND from the clinical symptoms and pathological findings.
Comparison of cytologic and histologic evaluations of the conjunctiva in the normal equine eye. To describe the cells observed in conjunctival brush cytology (CBC) from normal horses and compare these findings with conjunctival structural histology so as to understand which cells are recovered from CBC. Methods: This study was divided into three parts. (1) Conjunctival brush smears were collected from 20 healthy horses on both eyes and a differential count on 300 cells was carried out on May Grünwald-Giemsa (MGG) smears. (2) A similar protocol was used for whole eyes from five horses obtained rapidly after death from a slaughterhouse. The eyes were then assessed for conjunctival histolo...
Density and morphologic features of primary epidermal laminae in the feet of three-year-old racing Quarter Horses. To quantify the density of primary epidermal laminae (PELs) around the solar circumference and evaluate the relationship between regional PEL density and hoof capsule morphology in horses. Methods: Forefeet from nine 3-year-old Quarter Horse cadavers. Methods: Data pertaining to gross features of hoof morphology and PEL variables, including number, density, and distribution patterns around the perimeter of the hoof wall and number of bar PELs, were collected. Tissues of the laminar junction were examined histologically. Results: No significant differences were found between left and right fore...
Mesenchymal hamartoma of the liver in a late-term equine fetus. Mesenchymal hamartoma of the liver is a rare congenital disorder of biliary tract development. During the necropsy of a late-term equine fetus, a markedly enlarged liver of more than two times normal weight was found. Light microscopic review revealed that the normal hepatic parenchyma had been obliterated, replaced, and expanded by abnormal bile ducts surrounded by abundant, myxoid stroma. The lesion was diagnosed as a mesenchymal hamartoma. Small portions of the liver had bridging septa of fibrosis and proliferations of small-caliber abnormal bile ducts, resembling another congenital biliary...
Genetic correlations between performance traits and radiographic findings in the limbs of German Warmblood riding horses. Results of mare performance tests in the field (MPT-F) of 10,949 mares, mare performance tests at station (MPT-S) of 1,712 mares, and inspections of horses intended for sale at riding horse auctions (AU) of 4,772 horses were used to investigate genetic correlations between corresponding performance traits. Mare performance tests were held in 1995 to 2004 and auction inspections in 1999 to 2004. Scores on a scale from 0 to 10 were given for gaits under rider (walk, trot, canter), rideability (evaluated by judging commission and test rider), free-jumping (ability, style, total), and character. R...
Image fusion of computed tomographic and magnetic resonance images for the development of a three-dimensional musculoskeletal model of the equine forelimb. Biomechanical models that compute the lengths and forces of muscle-tendon units are broadly applicable to the study of factors that promote injury and the planning and effects of orthopedic surgical procedures in equine athletes. A three-dimensional (3D) generic musculoskeletal model of the equine forelimb comprised of bony segment, muscle-tendon, and ligament information, was developed based on high-resolution computed tomographic (CT) and T1-weighted magnetic resonance (MR) images from an isolated forelimb of a Thoroughbred racehorse. Image fusion was achieved through coregistration of CT an...
Defining cytochemical markers for different cell types in the equine retina. The major cell types in the mammalian retina are photoreceptors, amacrine, horizontal, bipolar, ganglion and Mueller glial cells. Most of the specific cell types are conserved, but cytochemical markers vary between species. The aim of our study was to characterize cytochemically distinctive markers for different cell types in the equine retina. We were able to define specific markers for equine Mueller glial cells and photoreceptor cells. Furthermore, we describe markers for large ganglion cells, horizontal and amacrine cells and a subpopulation of bipolar cells. Additionally, discrimination b...
Guttural pouches, brain temperature and exercise in horses. Selective brain cooling (SBC) is defined as the lowering of brain temperature below arterial blood temperature. Artiodactyls employ a carotid rete, an anatomical heat exchanger, to cool arterial blood shortly before it enters the brain. The survival advantage of this anatomy traditionally is believed to be a protection of brain tissue from heat injury, especially during exercise. Perissodactyls such as horses do not possess a carotid rete, and it has been proposed that their guttural pouches serve the heat-exchange function of the carotid rete by cooling the blood that traverses them, thus pro...
Evaluation of changes in architecture of the stratum internum of the hoof wall from fetal, newborn, and yearling horses. To evaluate morphologic changes of the stratum internum of hooves from near-term fetal, newborn, and yearling horses. Methods: Feet from 27 near-term equine fetuses, 19 newborn foals, and 8 yearlings. Methods: Primary epidermal laminae (PEL) of the stratum internum were examined for evidence of architectural changes. Results: In near-term fetuses, the PEL had a homogeneous appearance and symmetric distribution around the hoof wall with no significant differences in PEL density between the toe and quarters. However after birth, branched laminae at the toe formed within the first few weeks, whic...
Subchondral bone failure in overload arthrosis: a scanning electron microscopic study in horses. Mechanical overload leads to a common arthrosis in the metacarpal condyle of the fetlock joint of racehorses. This is usually asymptomatic but severe forms can cause lameness. Subchondral bone failure is often present and the predictability of the site provided an opportunity to study of the progression of bone failure from microcracks to actual collapse of subchondral bone. Twenty-five fetlock condyles from racehorses with various stages of disease were selected. Stages ranged from mild through severe subchondral bone sclerosis, to the collapse of bone and indentation or loss of cartilage kno...
The blood vessel system in the periodontal ligament of the equine cheek teeth–part I: The spatial arrangement in layers. Corrosion casts of blood vessels in the periodontium of cheek teeth from eight horses were observed three-dimensionally with a dissection microscope. Selected specimens were examined in a scanning electron microscope. Periodontal blood vessels communicated with those from the gingiva, the alveolar bone, and the apical region. In the upper jaw, there were anastomoses with the blood vessels of the mucosa of the maxillary sinus. The periodontal vascular system was organized in two or three layers. The peripheral layer was mainly composed of large venules, the inner one consisted of capillaries. I...
The blood vessel system in the periodontal ligament of the equine cheek teeth–part II: The micro-architecture and its functional implications in a constantly remodelling system. The micro-vasculature of the equine periodontal ligament (PDL) was investigated using corrosion casts for scanning electron microscopy. Specimens from eight healthy warm-blooded horses were examined. Specific vascular features such as large ampullae with a diameter of up to 300 microm and blind vascular casts were found in the specimens of the equine PDL. The ampullae-shaped venules occurred only in the peripheral layer, where they were formed at the confluence of several vessels. Two types of blind stumps were identified. The first was developed in all three layers, while the second was found...
Laparoscopic cryptorchidectomy and ovariectomy in horses. Laparoscopic surgery has become commonplace in the field of equine urogenital surgery. As with most surgical procedures, the limiting factors in developing new surgical techniques are limited to the patient size and demeanor, the skills of the surgeon, and the available equipment. Some of the greatest benefits of laparoscopic surgery in the horse include better visualization of the important structures; tension-free amputation of the testes or ovaries,which generally leads to less postoperative pain; and the ability to evaluate the transected stump carefully to make sure there is no hemorrhage...
Laparoscopic cryptorchidectomy and ovariectomy in horses. Laparoscopic surgery has become commonplace in the field of equine urogenital surgery. As with most surgical procedures, the limiting factors in developing new surgical techniques are limited to the patient size and demeanor, the skills of the surgeon, and the available equipment. Some of the greatest benefits of laparoscopic surgery in the horse include better visualization of the important structures; tension-free amputation of the testes or ovaries,which generally leads to less postoperative pain; and the ability to evaluate the transected stump carefully to make sure there is no hemorrhage...
