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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.
Seasonal analysis of the number of aeropiles in Anocentor nitens (Neumann, 1897) (Acari: Ixodidae) from the State of Rio de Janeiro, Brazil. Variation between aeropile numbers of the right and left peritrematic plate in male and female Anocentor nitens (Neumann, 1897) is reported from a site in Brazil. From January to December 1998, 146 males and 247 females of A. nitens were recovered from Equus caballus L. in Silva Jardim District, State of Rio de Janeiro. Asymmetry of numbers of aeropiles between right and left plates occurred in 83.6% of the males and 82.2% of the females. Differences in the number of aeropiles between the sexes were not significant. Quantitative variation of aeropiles was correlated to the period of recovery, ...
Marsupialization and iodine sclerotherapy of a branchial cyst in a horse. A 6-month-old Morgan colt was evaluated because of a 10-cm right-sided retropharyngeal swelling. The swelling was soft and moveable on examination, and palpation did not elicit signs of pain. Radiography revealed a large space-occupying mass ventral to the second cervical vertebra; ultrasonography revealed an anechoic fluid-filled structure with a well-defined hyperechoic capsule. Fine-needle aspiration yielded a viscous amber fluid. Cytologic evaluation indicated that the fluid was an exudate; anaerobic and aerobic bacterial culture did not yield any growth. Histologic examination of a portio...
Radiographic interpretation of normal skeletal variations and pseudolesions in the equine foot. Effective radiographic interpretation requires a veterinarian who is knowledgeable of equine limb anatomy and the various principles that affect the resulting image. The normal and its variations must be recognized and understood before the abnormal can be confidently identified as pathologic. Proper patient positioning and sound radiographic technique are mandatory if reliable diagnostic radiographs are to be produced. This review emphasizes equine foot radiographic variations of normal and pseudolesions that occur with commonly used radiographic views performed in equine practice.
Computed tomography and magnetic resonance imaging of the equine head. Horses are frequently presented with clinical conditions warranting diagnostic imaging of the head. Unfortunately, evaluation of the equine head can be difficult using conventional radiography. The anatomic complexity and superimposition of the osseous, dental, and soft tissue structures complicate radiographic interpretation and diagnoses. Multiple radiographic projections may be necessary to image specific regions, and side-to-side comparison is often essential.
Computed tomography and magnetic resonance imaging of the equine musculoskeletal conditions. There is a growing interest in the use of computed tomography (CT) and magnetic resonance (MR) imaging in equine orthopedic patients. It is well established that CT and MR imaging offer superior diagnostic information in a wide variety of musculoskeletal injuries in human beings and small animals. The highly detailed cross-sectional images obtained with these two modalities can often demonstrate pathologic changes undetected with other common imaging techniques. Based on their multiple applications in human beings and small animals, CT or MR imaging may prove to be the optimal diagnostic imagi...
Abdominal and thoracic radiography in the neonate. Plain and contrast radiographic techniques are used infrequently in the diagnostic evaluation of abdominal or thoracic disease in the adult horse because of the animal's large body size and the limited availability and expense of suitable equipment. The importance of radiography as a critical tool has also been lessened through the accessibility of ultrasound, although this technique is limited by depth and offers only a superficial window. Traditional radiographic techniques can be readily used in young foals because of their small body size, and radiography frequently provides critical infor...
Physical principles and technical considerations for equine computed tomography and magnetic resonance imaging. This article discusses how cross-sectional imaging methods such as computed tomography and magnetic resonance imaging can provide unique and diagnostically important information in situations where radiography or diagnostic ultrasound have been unrewarding.
Tubular aggregates observed in spindle muscle fiber of horse lumbrical muscle. Tubular aggregates (TAs) originate from the sarcoplasmic reticulum (SR) and form polymorphic double (or single) -walled structures in cross section. TAs are involved in various human skeletal muscle disorders including periodic paralysis, congenital myasthenic syndromes, inflammatory myopathies, and malignant hyperthermias. Horse lumbrical muscle (LM) is a slender fusiform muscle that shows varying degrees of regression due to its limited activity in the limb. Double-walled TAs were found in degenerating spindle fibers and with a range of 80-116 nm (average 92 nm, n=135) for outer layer and 50...
Animal type melanoma: a report of a case with balloon-cell change and sentinel lymph node metastasis. Animal type melanoma is a rare histopathologic variant of melanoma characterized by sheets and nodules of heavily pigmented epithelioid melanocytes that involve the entire thickness of the dermis. This human neoplasm mimics melanocytic neoplasms seen in gray horses and laboratory animals; thus, is termed animal type melanoma. It is quite rare and, with only a few reported cases, its biological behavior is not well understood. We report an example of animal type melanoma on the back of a 27-year-old man. The lesion showed areas of melanoma in situ, which ruled out the possibility of metastatic ...
Purification, crystallization and identification by X-ray analysis of a prostate kallikrein from horse seminal plasma. The purification, crystallization and identification by X-ray diffraction analysis of a horse kallikrein is reported. The protein was purified from horse seminal plasma. Crystals belong to space group C2 and the structure was solved by the MIRAS method, with two heavy-atom derivatives of mercury and platinum. X-ray diffraction data to 1.42 A resolution were collected at the ESRF synchrotron-radiation source.
Efficacy of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for the quantitative evaluation of the structural integrity of superficial digital flexor tendons in horses. To evaluate effectiveness of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for quantitative evaluation of tendon structural integrity in horses. Methods: 4 superficial digital flexor tendons (2 damaged tendons, 2 normal tendons). Methods: Transverse ultrasonographic images that precisely matched histologic sections were obtained in fixed steps along the long axis of each tendon. Distribution, intensity, and delineation of structure-related echoes, quantitatively expressed as the correlation ratio and steadiness ratio , were co...
A biomechanical comparison of headless tapered variable pitch and AO cortical bone screws for fixation of a simulated lateral condylar fracture in equine third metacarpal bones. To compare drilling, tapping, and screw-insertion torque, force, and time for the 4.5-mm AO and 6.5-mm Acutrak Plus (AP) bone screws, and to compare the mechanical shear strength and stiffness of a simulated complete lateral condylar fracture of the equine third metacarpal bone (MC3) stabilized with either an AO or AP screw. Methods: In vitro biomechanical assessment of screw-insertion variables, and shear failure tests of a bone-screw-stabilized simulated lateral condylar fracture. Methods: Eight pairs of cadaveric equine MC3s Methods: Metacarpi were placed in a fixture and centered on a biax...
[The fetlock tunnel syndrome in horses: literature review and retrospective study]. The annular ligament constriction is characterized by a disproportion between the available space and the contents within the fetlock tunnel. The main symptoms are a persisting lameness, distention of the tendon sheath, a typical "notch" when the fetlock is viewed from the side and a hyperflexion pain in the fetlock. The surgical treatment consists of the transection of the fetlock annular ligament. The conservative management can be considered as a independent therapy or as a preparation for a subsequent desmotomy. The medical records of 75 horses suffering from fetlock tunnel syndrome presen...
Morphological characteristics and distribution of the autonomic and sensitive innervation of the prostate in some animal species. The sensitive and autonomic innervation of the prostate was studied in some mammals (rat, rabbit, horse, donkey and bull) using gold chloride impregnation. In all the species considered the gland was supplied with conspicuous innervation located in the thickness of the capsule and in trabeculae. The autonomic innervation was constituted by ganglion cells of different sizes (small, medium and large), isolated or in groups of large ganglia also, always located along the course of nerve bundles. The sensitive nervous component, placed more frequently in the most superficial layer of the capsule, ...
Evaluation of a tapered-sleeve transcortical pin to reduce stress at the bone-pin interface in metacarpal bones obtained from horses. To evaluate stiffness and bone-pin interface stress for a transcortical tapered-sleeve pin (TSP) that incorporates bilateral tapered sleeves over a transcortical pin. Methods: 14 third metacarpal bones (MCIII) collected from adult horses of various breeds. Methods: Each MCIII was cut in half to provide 2 test specimens. Pins (conventional and TSP) of 3 diameters (6.35, 7.94, and 9.50 mm) were inserted in specimens (3 specimens for each diameter and each type of pin). The test fixture simulated a typical sidebar-span skeletal fixation device for horses. Single cycle load-deflection tests were p...
Cytoarchitectonic study of the cerebral cortex in the horse brain–classification of the cortex area. A cytoarchitectural classification of the horse cerebral cortex was done to determine whether functional locations exist or not such as found in the human cerebral cortex. Two adult horse brains were examined by Nissl and myelin stained methods. Six cell layers of the cerebral cortex were identified and classified into five types areas based on the cytoarchitectural organization: agranular, frontal, parietal, polar and granulous types. The agranular type was seen around the gyrus sylvius. In layer V of the agranular type, there were the many large cells that seemed like Betz cells. This type w...
Corneal stromal sequestration and keratoconjunctivitis sicca in a horse. A 19-year-old Shetland pony presented with unilateral ocular discomfort and abnormal ocular appearance. Keratoconjunctivitis sicca, ulcerative keratitis and brown discoloration of the corneal stroma were identified on ophthalmic examination. The etiology of keratoconjunctivitis sicca was not determined in this case. For practical and financial reasons, the owners requested enucleation of the affected eye. Histopathologic examination revealed extensive loss of corneal epithelium overlying a zone of hypereosinophilic, degenerate, and necrotic corneal stroma. This well-circumscribed region of cor...
Developmental anomalies and abnormalities of the equine iris. The iris is derived from interaction between neural crest tissue and the adjacent neuroectoderm of the optic cup. Developmental anomalies of the equine iris are common, and include congenital miosis, iris cysts, various manifestations of iris hypoplasia, heterochromia, and persistent pupillary membrane remnants. They may be found alone or in combination with other ocular defects.
Mucosal microvasculature of the gastric pars nonglandularis and margo plicatus in the horse: a scanning electron microscopic study on corrosion casts. The microvascularisation of the equine non-glandular gastric mucosa was investigated using corrosion casts for scanning electron microscopy. Specimens from 11 healthy horses were examined. Corresponding to the high incidence of gastric lesions in the margo plicatus, special attention was paid to the differentiation between the pars nonglandularis and the margo plicatus as a distinct area of the aglandular mucosa. In both areas, the blood vessels of the lamina propria mucosae were arranged in three vascular layers; i. e. I) a basal, II) an intermediate, and III) a subepithelial horizontal level...
Immunohistochemistry of the extracellular matrix of the normal equine lamina cribrosa. Purpose To use immunohistochemical techniques to identify and localize the structural macromolecules of the extracellular matrix (ECM) of the normal adult equine lamina cribrosa in order to make comparisons to the extracellular matrix of the lamina cribrosa of horses with glaucoma. METHODS: Normal eyes of five adult horses between 5 and 10 years of age were fixed in 10% neutral buffered formalin and embedded in paraffin. Polyclonal rabbit-derived antibodies against human elastin, laminin, fibrillin-1, and collagen types I, III and IV, and polyclonal goat-derived antibodies against collagen typ...
Disease of the equine posterior segment. The appearance of the equine fundus is reviewed from the perspective of differentiating normal variations from disease, and the descriptions have been updated to include recently published ocular fundic abnormalities. Most pathological lesions are identified near the optic nerve head, and typically involve depigmentation or hyperpigmentation. Depending upon configuration and appearance, linear pigmented bands may reflect the course of the vortex veins, the transition from tapetal to nontapetal fundus, or indicate chorioretinitis or equine motor neuron disease. Choroidal vasculature is readily ...
Light and electron microscope studies on the nasopharynx and nasopharyngeal tonsil of the horse. Light and electron microscope studies were conducted on the nasopharynx and the nasopharyngeal tonsil of 15 young horses. The nasopharynx and nasopharyngeal tonsil was lined with pseudostratified columnar ciliated epithelium and goblet cells. The lymphoepithelium of the nasopharyngeal tonsil was folded forming crypts, the mucosa of which was modified into follicle associated epithelium characterized by stratified cuboidal epithelium, loss of cilia, absence of goblet cells and infiltration of lymphocytes. The lamina propria mucosae of the nasopharyngeal tonsil contained well-developed lymphoid ...
Diagnosis of small intestinal intussuception by transabdominal ultrasonography in 2 adult horses. Transabdominal ultrasonography is frequently used to diagnose small intestinal intussusceptions in foals. We demonstrate that transabdominal ultrasonography also provides a rapid and accurate diagnosis of small intestinal intussusception in adult horses. A detailed description of the ultrasonographic appearance is provided.
