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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.
Tissue culture of the enteric nervous system from equine ileum. Ileal samples were harvested fresh from euthanized adult horses. The tissues were microdissected to prepare wholemount preparations for immunohistochemistry and for either explant or dissociated culture systems of the enteric nervous system. Explant culture systems were established using whole-mounts of either the submucous plexus or the muscularis externa (including the myenteric plexus). Dissociated cell cultures could only be obtained from the submucous plexus. Culture systems were maintained for up to 5 days. Immunoreactivity for a neuronal marker (Pan-N) and for glial cell markers (GFAP a...
Gonadotroph-lactotroph associations and expression of prolactin receptors in the equine pituitary gland throughout the seasonal reproductive cycle. An interaction between gonadotroph and lactotroph cells of the pituitary gland has long been recognized in several species. The current study was conducted to investigate whether an association between gonadotrophs and lactotrophs occurs in mares and whether prolactin receptors are expressed within the pituitary gland of this species. The effects of both reproductive state and season on these variables were examined in pituitary glands obtained from sexually active mares in July (breeding season), sexually active mares in November (non-breeding season) and anoestrous mares in November. Pituita...
Concrete use of the joint coordinate system for the quantification of articular rotations in the digital joints of the horse. A method is detailed allowing the computation of three-dimensional (3D) joint angles. Each joint of the equine digit is modelled as a sequence of three single axis rotary joints. The Joint Coordinate System was used; it involves a specific sequence of cardanic angles. The decomposition of the angles was chosen so that the three elementary angles coincide with the flexion/extension, passive abduction/adduction and lateral/medial rotations. The algorithms and kinematic procedures were described for the equine front digital joints. This method was tested in vitro on four forelimbs. For each limb,...
Raman optical activity characterization of native and molten globule states of equine lysozyme: comparison with hen lysozyme and bovine alpha-lactalbumin. Vibrational Raman optical activity (ROA) spectra of the calcium-binding lysozyme from equine milk in native and nonnative states are measured and compared with those of the homologous proteins hen egg white lysozyme and bovine alpha-lactalbumin. The ROA spectrum of holo equine lysozyme at pH 4.6 and 22 degrees C closely resembles that of hen lysozyme in regions sensitive to backbone and side chain conformations, indicating similarity of the overall secondary and tertiary structures. However, the intensity of a strong positive ROA band at approximately 1340 cm(-1), which is assigned to a hydrat...
Neurocalcin-immunoreactive neurons in the mammalian dorsal root ganglia, including humans. Neurocalcin (NC) is a recently characterized EF-hand calcium-binding protein present in a discrete population of sensory neurons and their peripheral mechanoreceptors, but its presence in peripheral nervous system neurons other than in the rat is still unknown. The present study was designed to investigate the occurrence of NC in the dorsal root ganglia (DRG) of several mammalian species (horse, buffalo, cow, sheep, pig, dog, and rat), including humans. DRG were fixed, embedded in paraffin, and processed for immunohistochemistry using a polyclonal antibody against NC. The size of the immunorea...
Vacuum phenomenon in equine carpal, metacarpophalangeal and metatarsophalangeal joints. In order to establish the incidence of vacuum phenomenon in horses' carpal, metacarpophalangeal and metatarsophalangeal joints, stress-flexed radiographs were made of normal joints, joints with known pathology and in anaesthetised horses with joints under traction. Focal intra-articular radiolucencies were identified in normal stress-flexed carpal, metacarpophalangeal and metatarsophalangeal joints. These radiolucencies can be confused with those associated with pathological conditions.
Concentrations of substance P and prostaglandin E2 in synovial fluid of normal and abnormal joints of horses. To correlate substance P content of synovial fluid with prostaglandin E2 content, radiographic evidence of joint abnormality, and anatomic location of the joint for normal and osteoarthritic joints of horses. Methods: Synovial fluid from 46 normal joints in 21 horses and 16 osteoarthritic joints in 10 horses. Methods: Normal and osteoarthritic joints were identified by clinical and radiographic examination, by response to nerve blocks, during scintigraphy or surgery, or by clinicopathologic evaluation. Substance P and prostaglandin E2 contents of synovial fluid were determined by radioimmunoas...
Influence of interleukin-1beta and hyaluronan on proteoglycan release from equine navicular hyaline cartilage and fibrocartilage. Proteoglycan (PG) release, in response to recombinant human interleukin-1beta (rh-IL-1beta), was measured in cartilage explants obtained from the equine distal sesamoid bone (navicular bone). Fibrocartilage from the surface of the navicular bone apposing the deep digital flexor tendon and hyaline cartilage from the surface of the navicular bone articulating with the middle phalanx were labelled with 35SO4. Hyaline cartilage from the distal metacarpus was used as a control tissue. Following radiolabel incorporation, the three cartilage types were treated with rh-IL-1beta (100 U/mL) in the prese...
Study of the hyaloid apparatus in the neonatal thoroughbred foal. Over 80 per cent of 169 neonatal thoroughbred foals had some part of the hyaloid artery present bilaterally and its degree of completeness, colour and character was statistically symmetrical. The complete artery was present in over 60 per cent of the foals. The incidence of the hyaloid artery and its completeness, colour and character were related to the age of the foal. The hyaloid system atrophies in the early stages of the neonatal period and generally its presence did not cause any significant ocular problems. The presence and morphology of the posterior pupillary membrane was highly corre...
Functional adaptation of equine articular cartilage: the formation of regional biochemical characteristics up to age one year. Biochemical heterogeneity of cartilage within a joint is well known in mature individuals. It has recently been reported that heterogeneity for proteoglycan content and chondrocyte metabolism in sheep develops postnatally under the influence of loading. No data exist on the collagen network in general or on the specific situation in the horse. The objective of this study was to investigate the alterations in equine articular cartilage biochemistry that occur from birth up to age one year, testing the hypothesis that the molecular composition of equine cartilage matrix is uniform at birth and b...
An in vitro study to compare 5 different techniques for injection of the navicular bursa in the horse. Numerous different techniques for injection of the navicular bursa have been described but there is little conformity between these descriptions. A literature review was performed and techniques for injection of the navicular bursa were categorised into 5 approaches. This study was performed to evaluate the reproducibility of each technique and to assess which technique was consistently most successful. Five inexperienced operators performed each technique on 5 cadaver forelimbs. Once a needle had been placed, a radiograph was taken to confirm placement was in accordance with the description o...
Molten globule structure of equine beta-lactoglobulin probed by hydrogen exchange. The molten globule structure of equine beta-lactoglobulin has been inferred from the hydrogen exchange protection of the backbone amide protons. In order to make it possible to measure the hydrogen exchange kinetics of the individual backbone amide protons, the uniformly (15)N-labeled recombinant protein was expressed in Escherichia coli and the NMR peak assignment was obtained for most of the backbone protons. The chemical shift and NOE results obtained under the condition where the protein assumes the native structure are fully consistent with the known secondary structure of bovine beta-lac...
Ultrastructure of the horse tongue: further observations on the lingual integumentary architecture. This investigation examined primarily epidermal specializations of the adult horse tongue by light, scanning and transmission electron microscopy. Samples were collected from seven regions of the normal tongue of various breeds of horse. The filiform papillae, present on the dorsal and lateral aspects but not the ventral aspect of the tongue, were short, slender and finger-like structures with variable-shaped terminae. The epidermal thickness and height of dermal ridges were reduced on fungiform and vallate papillae, but tissue architecture and keratinocyte ultrastructure of most of the lingua...
Autologous morsellised bone grafting restores uncontained femoral bone defects in knee arthroplasty. An in vivo study in horses. The properties of impacted morsellised bone graft (MBG) in revision total knee arthroplasty (TKA) were studied in 12 horses. The left hind metatarsophalangeal joint was replaced by a human TKA. The horses were then randomly divided into graft and control groups. In the graft group, a unicondylar, lateral uncontained defect was created in the third metatarsal bone and reconstructed using autologous MBG before cementing the TKA. In the control group, a cemented TKA was implanted without the bone resection and grafting procedure. After four to eight months, the animals were killed and a biomechan...
Electrically elicited blink reflex in horses with trigeminal and facial nerve blocks. To reassess reference values for the components of the electrically induced blink reflex, document reference values for facial motor nerve conduction velocity, and demonstrate usefulness of the blink reflex as a diagnostic tool in peripheral facial and trigeminal nerve dysfunction in horses. Methods: 10 healthy adult horses (8 males, 2 females) without neurologic abnormalities. Methods: Blink reflex tests were performed by electrical stimulation of the supraorbital nerve and facial (auriculopalpebral) nerve. Reflex and direct muscle-evoked potentials of the orbicularis oculi muscles were recor...
Corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa or clinically normal corneas. To compare corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa and those with clinically normal corneas. Methods: 129 Rocky Mountain Horses. Methods: Ultrasonic pachymetry was used to measure corneal thickness. Applanation tonometry was used to measure intraocular pressure. A Jameson caliper was used to measure optical corneal diameter. Results: The central and temporal peripheral portions of the cornea were significantly thicker in horses with cornea globosa than in horses with clinically normal corneas, but corneal thicknesses in...
Osteoclastic resorption of equine cranial and postcranial bone in vitro. To address possible differences in the resorbability of cranial and postcranial bone, slices of equine frontal bone and leg (first phalanx or third metacarpus) were seeded with embryonic chick bone cells and cultured for 20-24h. After removing the cells and drying the specimens, the areas and volumes of more than 800 resorption pits in each set were measured using a video-rate reflection confocal microscope system. Relative mineralization densities were determined by quantitative electron backscattering analysis. The mean mineralization density was greater in the leg bone, but the mean depths ...
Macroscopic anatomy of the auditory tube diverticulum (guttural pouch) in the thoroughbred equine–a silicon mold approach. The characteristics of the equine auditory tube diverticulum (guttural pouches) were studied in detail by the naked eye and silicon mold method. First, we examined the anatomical relationship between the guttural pouches and their associated bones and muscles. Secondly, a silicon mold was fabricated to clarify the three-dimensional aspect of the guttural pouches, paying a special attention to the distribution of major arteries and nerves surrounding it. Thirdly, the volume of the silicon mold was measured by immersing it in water. The guttural pouches are a pair of pouches located dorso-poster...
Low-field magnetic resonance imaging of the equine tarsus: normal anatomy. The objective of this study was to define the normal gross anatomic appearance of the adult equine tarsus on a low-field magnetic resonance (MR) image. Six radiographically normal, adult, equine tarsal cadavers were utilized. Using a scanner with a 0.064 Tesla magnet, images were acquired in the sagittal, transverse and dorsal planes for T1-weighted and the sagittal plane for T2-weighted imaging sequences. Anatomic structures on the MR images were identified and compared with cryosections of the imaged limbs. Optimal image planes were identified for the evaluation of articular cartilage, subch...
Scintigraphic characterization of distal radial physeal closure in young Standardbred racehorses. A longitudinal scintigraphic and radiographic study of distal radial physeal activity in 14 Standardbred trotters was conducted to quantify and visually evaluate physeal uptake around the time of physeal closure. Initial intense 99mTc-HDP uptake was seen, followed by a rapid decrease of activity starting at a mean age of 20 months. Mean physeal to distal diaphyseal ROI and line profile ratios compared to ratios of mature horses decreased from 2.8 to 1.4 at the time of radiographic closure at 24-32 months. Ratios then gradually decreased until values of mature horses were reached at the end of ...
Measuring sphere-like structures using transrectal ultrasonography. Sphere-like structures are commonly measured for clinical or research purposes. We measured two diameters, the circumference (perimeter) and cross sectional area of 113 equine ovarian follicles in a water bath then determined the relationships between those measurements and the actual volume of fluid in the follicles. Cross-sectional area, diameter3 and area2/3 were all highly correlated with the volume of the structures and superior (p 0.05) between cross-sectional area, diameter3, and area2/3. Because of the ease of measuring diameter, we suggest that diameter3 be used to estimate the actua...
Omphalocele in a foal. An omphalocele was detected at birth in a male Arabian foal. The mass contained small intestine and after releasing a constricting band at the body wall, the contents slipped easily back into the abdomen. On the outside was the hairless pink membrane. The interior, now empty of small intestine, contained the umbilical arteries and vein, and a large urachus that extended from the bladder to the opening at the extremity of the mass. Six days after corrective surgery the foal was sent home and remained healthy.
Use of radiography, computed tomography and magnetic resonance imaging for evaluation of navicular syndrome in the horse. Radiographic evaluation of navicular syndrome is problematic because of its inconsistent correlation with clinical signs. Scintigraphy often yields false positive and false negative results and diagnostic ultrasound is of limited value. Therefore, we assessed the use of computed tomography and magnetic resonance imaging in a horse with clinical and radiographic signs of navicular syndrome. Cadaver specimens were examined with spiral computed tomographic and high-field magnetic resonance scanners and images were correlated with pathologic findings. Radiographic changes consisted of bony remodel...
Cross-species and intraspecies morphometric analysis of the corpus callosum. A cross-species morphometric study of the corpus callosum was performed in the rat, rabbit, cat, dog, horse, cow and human. Across species, the results indicate a strong, although less than linear, dependency of callosal size on brain weight. This relation tends to lose significance within species. This is consistent with other morphometric studies indicating a tendency to decrease the correlations between morphometric variables in within-species analyses as compared to between-species analyses. There are species differences in the relative size of some callosal segments particularly in the po...
Basic three-dimensional kinematics of the vertebral column of horses walking on a treadmill. To determine kinematic movements of the vertebral column of horses during normal locomotion. Methods: 5 Dutch Warmblood horses without apparent lameness or problems associated with the vertebral column. Methods: Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Horses were recorded while walking on a treadmill at a constant speed of 1.6 m/s. Results: Flexion-extension was characterized by 2 periods of extension and flexion during 1 stride cycle, whereas lateral bending and axial rotation were characterized by 1 p...
Shape, orientation and spacing of the primary epidermal laminae in the hooves of neonatal and adult horses (Equus caballus). Circumferential and proximodistal variations in the morphology of the primary epidermal laminae of six neonatal and five adult equine feet were documented. Three parameters were quantified: interlaminar spacing, the orientation of the laminae with respect to the overlying wall, and any angulation within the laminae themselves ('internal angle'). In adult feet, the laminae were most closely spaced at the dorsum, the spacing increasing gradually towards the heels. In foals there was a non-significant trend for the dorsal laminae to be more widely spaced than those in more caudal parts of the foo...
The study of cutaneous melanomas in Camargue-type gray-skinned horses (1): clinical-pathological characterization. The clinical and pathological characteristics of cutaneous melanomas occurring in Camargue-type gray-skinned horses are reported. Examination of 83 tumor-bearing horses revealed that the tumors occurred most frequently underneath the tail (93.9%) and at high rates in the peri-anal region (43.0%), the lips (33.0%), and the eyelids (24.0%), but rarely in the vulva (3.8%). Tumorous lesions were characterized by the presence of either hemispheric nodules or large infiltrated plaques, or their combinations. Microscopic examination indicated that tumorous lesions were composed mostly of melanocytes ...
Equine osteoclast-like cells generated in vitro demonstrate similar characteristics to directly isolated mature osteoclasts. We report on novel methods to isolate osteoclasts (OC s) and generate osteoclast-like cells (OCL s) from the bone and bone marrow of the equine femur. OC s were successfully isolated from bone scrapings taken from the endosteal surface of the femurs of three horses. OCL s were generated from bone marrow cells taken from the same animals. The validity of using the formation of OCL s as a method for studying OC differentiation and activity was confirmed by the similar characteristics of these two cells. In particular, they both were multinuclear, expressed the enzyme tartrate resistant acid phos...
