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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.
Tubule density of the stratum medium of horse hoof. The number of tubules/mm2 (tubule density) of horse hoof horn was quantified in samples taken from the left forefeet of 8 randomly selected slaughterhouse horses in order to establish the normal tubule density characteristics at the midline dead centre (MDC) for the stratum medium of horse hoof. In the past the measurement of tubule distribution within the hoof has lacked objectivity. The horse hoof tubule density results are compared to a recent objective study carried out on pony hoof. A similar 4 zone pattern of tubule density was observed, although the precise zonal boundaries and tubule d...
Effect of hoof trimming on the occurrence of distal phalangeal palmar process fractures in foals. This study sought to determine if extensive trimming of the front hooves of foals results in a higher incidence of palmar process fractures compared to untrimmed foals, and to characterise the clinical course of foals with palmar process fractures with physical findings, hoof measurements and radiography. Twenty foals age 4-8 weeks of multiple breeds were examined every 2 weeks over a 12 week period. Ten foals had both front hooves extensively trimmed every 4 weeks, while 10 foals remained untrimmed. Palmar process fractures occurred in 4 trimmed and 3 untrimmed foals. Four foals with fracture...
In vitro attenuation of impact shock in equine digits. This study was designed to test the impact characteristics of the equine digit in vitro with the objective of providing a better understanding of the role of the digital structures in the attenuation of impact shock. Uni-axial accelerometers were mounted on cadaver digits on the distolateral hoof wall, the proximolateral hoof wall, the dorsal surface of the second phalanx, and the mid-lateral first phalanx. The hoof-mounted accelerometers were aligned with the hoof tubules while the bone-mounted accelerometers were oriented along the longitudinal axis of the bone. Each digit was mounted in a t...
Exploring the possible functions of equine hoof wall tubules. Possible functions of equine hoof wall tubules were investigated in this study. Hydration tests were conducted on blocks of hoof wall tissue in order to test the hypothesis that hollow tubules facilitate the conduction of water vapour distally. Although water loss or gain was inhibited through the outer wall surface, the increase in surface area provided by medullary spaces was ineffective in facilitating hydration through the face with exposed tubule ends. Rather, hollow tubules appear to allow for a higher dehydration rate through their exposed ends. Analysis of medullary space indicates tha...
Cytokeratins of the equine hoof wall, chestnut and skin: bio- and immunohisto-chemistry. The equine skin and its appendages (chestnut, hoof capsule, ergot, sebaceous glands, sweat glands and hair) consist mainly of keratinocytes. The intermediate filament cytoskeleton of these cells in involved in specialised functions, such as mechanical co-ordination of the cytoskeleton of the cell or tissue. In this study, 7 monoclonal antibodies, one polyclonal antibody and immunoblot analysis were used to characterise cytokeratins (separated by 1- and 2-dimensional gel electrophoresis) from the hoof wall and chestnut. The tissue distribution of these cytokeratins was studied by immunohistoche...
Fetal development of the white line (Zona alba) of the equine hoof. The fetal development of the white line (Zona alba) in the equine hoof is described. Its specific structure of lamellar and interlamellar horn, which in turn is composed of cap and terminal horn, is formed in the second half of the hoof's fetal development. In equine fetuses with a crown-rump length of less than 550 mm, the hoof capsule lacks a 'characteristic' white line since no borders between stratum medium, stratum internum and sole horn are discernible. In the hoof of an equine fetus with a crown-rump length of 550 mm, a narrow white line has taken shape. Its shallow lamellae are arrange...
The development of microcracking and failure in bone depends on the loading mode to which it is adapted. During locomotion, the anterior cortex of the equine radius is loaded predominantly in tension, the posterior predominantly in compression. The anterior cortex is relatively strong in tension, the posterior in compression. We investigated the pattern of failure of specimens from the two cortices using laser scanning confocal microscopy. All specimens were loaded in four-point bending to increasingly higher loads. We quantified the amount of diffuse microcracking on the tensile side of these specimens by observing the amount of light emitted under laser illumination. The amount of light emitted...
Incarceration of the small colon through a rent in the gastrosplenic ligament in a pony. A 10-year-old castrated male pony was examined for intermittent signs of abdominal pain of 3 days' duration. An incarceration of the small colon through a rent in the gastrosplenic ligament was found. Resection and end-to-end anastomosis were performed on the affected portion of the small colon. The pony recovered and returned to its previous degree of activity. Incarceration of the small intestine and large colon through rents in the gastrosplenic ligament are documented, although involvement of the small intestine is more common. To the best of our knowledge, incarceration of the small colon...
Endoscopy of the intertubercular bursa in horses. Forelimbs from 3 anesthetized horses and 16 fresh cadaver horses were used to describe the endoscopic anatomy of the intertubercular bursa and outline the surgical portals that provide the greatest access to structures within the bursa. A lateral arthroscopic portal was made proximal to the deltoid tuberosity of the humerus into the distal bursal recess. A second portal was created proximal to the humeral tubercles that entered the proximal bursal space. These approaches provided consistent viewing and instrument access to the lateral intertuberal groove, the greater and intermediate humeral t...
Morphology of the oocyte-follicular connection in the mare. The present study characterised the oocyte-follicular connection (i.e., oocyte fixation site) in Graafian follicles of the mare morphologically. Antral follicles were dissected in toto from ovaries obtained from oestrous, dioestrous and transitional mares after slaughter. The location of the cumulus oophorus complex in relation to the ovulation fossa, the width and density of the blood vessels surrounding the cumulus oophorus complex, the relative dimensions and histological aspects of the cumulus oophorus were investigated. For ultrastructural analysis of the junctional regions, cumulus-oocyt...
Paranasal sinus cyst as a cause of stridor in a standardbred colt. Sinus cysts are epithelium-lined, fluid-filled cavities that can occur in the paranasal sinuses of horses. Extensive damage to the permanent tooth buds was a significant feature in this case. The sequellae of these abnormalities, although not apparent at the time of presentation, remain an important consideration for prognosis.
Instability-induced osteoarthritis in the metacarpophalangeal joint of horses. To establish an instability model of osteoarthritis (OA) that mimics the early changes of naturally acquired OA. Methods: 6 mature radiographically normal horses. Procedure-The collateral and lateral collateral sesamoidean ligaments were transected in a metacarpophalangeal (MCP) joint in each horse. Lameness examinations were performed every 7 days after surgery for 8 weeks. Radiographs were taken immediately before and after desmotomy and 8 weeks after surgery. Eight weeks after surgery, bilateral MCP joints were grossly evaluated, specimens of articular cartilage were harvested for histologi...
Micromechanics of the equine hoof wall: optimizing crack control and material stiffness through modulation of the properties of keratin. Small-scale components of the equine hoof wall were tested to determine their mechanical roles in the morphological hierarchy. Macroscale tensile tests conducted on samples of the inner wall tubules and intertubular material showed a sixfold difference in mean initial stiffnesses (0.47 and 0.08 GPa, respectively), indicating that the inner wall tubules stiffen the wall along its longitudinal axis. The similarity in material properties of tubule and intertubular samples from the mid-wall suggests that tubules in this region offer only minor reinforcement along the longitudinal axis. Microscale ...
Tumors of the eye and ocular adnexal tissues. This article reviews options in dealing with tumors of the cornea and conjunctiva, nictitating membrane neoplasms, and eyelid neoplasms. Orbital tumors, optic nerve and other intraocular tumors are also discussed.
A comparison of porosity, fabric and fractal dimension as predictors of the Young’s modulus of equine cancellous bone. The purpose of this study was to compare the structural parameters of fabric and fractal dimension as predictors of the Young's modulus of equine cancellous bone. Eight 15 mm cubes of cancellous bone were obtained from three equine third metacarpal bones. Young's modulus was determined for the three orthogonal directions. The fabric and fractal dimension were calculated for each of the six exposed faces of each cube. Fractal dimension plus porosity provided a higher explanatory power for Young's modulus (R2 = 78.7%. P < 0.0001) than fabric plus porosity (R2 = 69.2%, P < 0.0001). Fractal ...
Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses. To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses. Methods: 95 Thoroughbred racehorses that died between 1994 and 1996. Methods: 38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Com...
[Radiologic description of the growth plates of the atlas and axis in foals]. Fractures of the first two cervical vertebrae, atlas and axis, may occur in foals for different reasons, e.g. in cases of a fall, going head over heels or when being hit by a hoof. The tentative clinical diagnosis can be confirmed by x-raying the standing animal, with aid of computed tomography in the anaesthetized foal respectively. The growth plates however, and their time of closure have to be considered when interpreting radiographs. In the atlas there are two ventrolateral plates and one dorsomedian cartilagineous plate. Only the dorsal plate, however, can be found in the dorsoventral pro...
Possible significance of cells within intraluminal collagen masses in equine oviducts. In addition to the unique feature of retention of unfertilized ova, the oviducts of mares frequently contain large intraluminal masses with a fibrillar component and some cells. The aim of this study was to identify the cells and examine their relationship to the extracellular components of these masses. Intraluminal masses were examined both in situ and flushed from the oviducts. The nature of the contained cells and their relationship to the fibrils were examined by light microscopy and by transmission and scanning electron microscopy. In some mares the large masses distended the oviduct, bu...
Endoscopy of the calcaneal bursa in horses. To describe endoscopic approaches to the calcaneal bursa and clinical findings in 2 horses with calcaneal bursitis. Methods: Cadaver evaluations and retrospective case reports. Methods: 12 cadavers and 2 adult horses. Methods: Cadaver specimens of the calcaneal bursa were evaluated with a rigid arthroscope and gross dissection to determine the endoscopic appearance of anatomic structures located within the bursa. The site(s) for placement of the arthroscope and instrument(s) was determined based on cadaver dissection and endoscopic examination. Results: Placement of the arthroscope 1 cm dorsal...
A comparison of the Synthes 4.5-mm cannulated screw and the Synthes 4.5-mm standard cortex screw systems in equine bone. To determine risk of failure of the Synthes 4.5-mm cannulated screw system instrumentation in equine bone and to compare its application with the Synthes 4.5-mm standard cortex screw system. Methods: The maximum insertion torque of the cannulated and standard cortex screw systems were compared with the ultimate torsional strengths of the equipment. Pullout strength and ultimate tensile load of cannulated and standard cortex screws were also determined. Methods: Paired equine cadaver third metacarpal and third carpal bones. Methods: Maximum insertion torque and ultimate torsional strengths were...
Innervation of the equine mature and immature proximal sesamoid bone by calcitonin gene-related peptide and substance P-containing nerves. To localize and determine relative frequency of occurrence of calcitonin gene-related peptide (CGRP) and substance P (SP) fibers in the proximal sesamoid bones (PSB) and adjacent structures in sound horses. Methods: 4 foals and 3 adult horses. Methods: Medial PSB and adjacent ligaments of both forelimbs were collected, flushed, and fixed in buffered 4% formalin. The left PSB were cut into 5 longitudinal, sagittally oriented slabs, and the right PSB were cut into 5 transverse slabs. After decalcification in EDTA, slices were transferred to a 30% sucrose solution, deep frozen, sectioned (80 micr...
Persistent right aortic arch in a yearling horse. A 14-month-old filly with chronic pharyngitis was diagnosed with incomplete esophageal constriction and megaesophagus due to a persistent right aortic arch. This report is unusual because clinical signs of respiratory dysfunction secondary to chronic regurgitation occurred prior to the recognition of dysphagia.
Anatomo-radiographic study on the osteogenesis of carpal and tarsal bones in horse fetus. The aim of this study is to point out the time of appearance of the carpal and tarsal bones in the fetal horse, considering an estimated fetal age, to follow their morphological development through to birth, and to characterize possible abnormal shape and/or delay of their ossification. The right carpal and tarsal region of 140 equine fetuses of both sexes (71 males, 69 females) and different ages (from 70 to 340 days of gestation) were examined radiographically in order to identify the sites of ossification from their earliest appearance. The times of appearance of the sites of ossification o...
Immunohistochemical localization of the spermadhesin AWN-1 in the equine male genital tract. Spermadhesins are proteins with various functions in sperm capacitation and zona pellucida binding. In this study the cellular localization of the spermadhesin AWN-1 has been examined in the equine male genital tract. Results obtained by immunohistochemical methods reveal that in the horse AWN-1 is synthesized in spermatogonia, in the rete testis, the ductus epididymidis and the seminal vesicles. These findings indicate that the cellular origin of spermadhesins is species-specific.
In-shoe foot force sensor to assess hoof balance determined by radiographic method in ponies trotting on a treadmill. Adaptation of an in-foot shoe force sensor and the gait analysis system 'Fscan' makes it possible to monitor the distribution of the vertical forces under the equine foot in motion. The aim of this study is to investigate the effects of two different trimmings on forces under the foot during the trot. The first one increased the height of the lateral hoof wall and the second one restored the mediolateral balance of the foot. These two trimmings were examined by using a radiographical method that quantifies the interphalangeal articular asymmetries due to asymmetrical bearing. The location of t...
Radiographic assessment of equine interphalangeal joints asymmetry: articular impact of phalangeal rotations (Part I). This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs on a rotation support to study the influence of induced foot rotations on several angles measured from specific radiographs. The results of this work enabled the authors to quantify the rotation of the proximal phalanx compared to the distal, and to determine exactly the possible rotation in the distal interphalangeal joint. It was also observed that, faced with a forced rotation of the foot, t...
Radiographic assessment of equine interphalangeal joints asymmetry: articular impact of asymmetric bearings (Part II). This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs fastened on a rotation support with variable inclinations to study the influence of induced asymmetric bearings on various angles measured from specific radiographs. The digit responded to asymmetric bearings by 1. deformation of the hoof; 2. rotation of the phalanges; and 3. joint asymmetry or local articular space narrowing. The two last situations occurred mainly in the distal interphalangea...
Imaging basilar skull fractures in the horse: a review. Due to the complex nature of the anatomy of the equine head, superimposition of numerous structures, and poor soft tissue differentiation, radiography may be of limited value in the diagnosis of basilar skull fractures. However, in many horses radiographic changes such as soft tissue opacification of the guttural pouch region, irregular bone margination at the sphenooccipital line, attenuation of the nasopharynx, ventral displacement of the dorsal pharyngeal wall and the presence of irregularly shaped bone fragments in the region of the guttural pouches are suggestive of a fracture of the skul...
The accuracy of the dorsoproximal-dorsodistal projection in assessing third carpal bone sclerosis in standardbred trotters. Thirty-five carpal joints from 20 standardbred trotters, age 1 to 7 years, all euthanized for nonorthopedic reasons, were examined to investigate the correlation between assessments of subchondral bone sclerosis in the third carpal bone from radiographs in the dorsoproximal-dorsodistal (DPr-DDi) projection and histomorphometric bone volume density measurements. The agreement between assessments of sclerosis from antemortem versus postmortem radiographs was also evaluated. Bones graded as sclerotic in the DPr-DDi projection had significantly higher bone volume density values for all areas of me...
