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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.
[Interactive educational DVD on hoof protection, horseshoeing and diseases of the hoof]. Good cooperation between farrier, veterinarian and horse owner is an important prerequisite for optimal support of the horse with regards to shoeing and hoof health. The introduction of a joint educational aid aims to improve the level of education of both veterinarians and farriers. The interactive, multimedia approach represents an innovative new dimension in instruction techniques, predominantly provided through images and videos. The contents of the new teaching aid will focus on detailed anatomy of the foot and distal limb, as well as currently accepted shoeing practices and techniques an...
Kinematics of the equine temporomandibular joint. To develop a method of measuring 3-dimensional kinematics of the temporomandibular joint (TMJ) in horses chewing sweet feed. Methods: 4 mature horses that had good dental health. Methods: Markers attached to the skin over the skull and mandible were tracked by an optical tracking system. Movements of the mandible relative to the skull were described in terms of 3 rotations and 3 translations. A virtual marker was created on the midline between the rami of the mandibles at the level of the rostral end of the facial crest to facilitate observation of mandibular movements. Results: During the ope...
Immunohistochemical identification of lymphatic vessels in the periodontium of equine cheek teeth. Immunohistochemical detection of lymphatic capillaries was performed in the periodontium of maxillary and mandibular cheek teeth from 6 horses (aged 3-23 years). Tissue sections of the periodontium were taken at 4 different horizontal levels along the long axis of the tooth. The specimens were processed for immunoreaction with anti-Prox1, in order to distinguish lymphatic endothelium from blood vascular endothelium. Lymphatic vessels were detected in all periodontal tissues except for the dental cementum. Lymphatic capillaries were most densely distributed in the gingiva compared to other tiss...
The presence of androgen receptors in the epididymis and prostate of the stallion and cryptorchid horse–a preliminary study. Distribution of androgen receptors (ARs) in the epididymal duct and prostate of three entire stallions and one bilaterally cryptorchid horse was studied immunohistochemically using a polyclonal rabbit antiserum against the ARs. In both the healthy stallions and the cryptorchid, the epithelial cells of the epididymides showed nuclear staining for ARs. The intensity of AR-staining in the principal cells of the epididymis was stronger than that of the basal cells. In the prostate, the glandular secretory cells were moderately stained whereas the basal cells expressed weak AR-staining. Immunostain...
Rhythm of engorgement and detachment of Anocentor nitens females feeding on horses. The present study evaluated the engorgement and drop-off rhythms of Anocentor nitens females feeding on horses. Drop-off rhythm was evaluated at 6h-intervals (06:00, 12:00, 18:00, and 00:00 h) on horses held in stalls or in a pasture. A new method of marking feeding female ticks (the bowknot technique) was developed to evaluate ticks on horses in pasture that attached to different parts of the horse's body. This technique was highly successful, indicating no significant interference on tick engorgement rate or final tick weight, length and reproductive capability. Horses held in the pasture du...
Osteocyte lacuna population densities in sheep, elk and horse calcanei. Osteocytes, the most prevalent cell type in bone, appear to communicate via gap junctions. In limb-bone diaphyses, it has been hypothesized that these cellular networks have the capacity to monitor habitual strains, which can differ significantly between cortical locations of the same bone. Regional differences in microdamage associated with prevalent/predominant strain mode (tension, compression, or shear) and/or magnitude may represent an important "variable" detected by this network. This hypothesis was indirectly addressed by examining bones subjected to habitual bending for correlations o...
Histology of two rice bodies isolated from the stifle of an adult draught horse stallion. In the human and equine species, different kinds of free floating intra-articular particles are related to certain disorders. Osteochondral fragments formed during osteochondrosis dissecans are the most common finding in the equine species, whereas in humans rice bodies due to rheumatoid arthritis are more frequent. Herein we report a third type of floating body inside the stifle of an adult draught horse stallion, in macroscopic appearance similar to articular rice bodies known in humans. As revealed by histologic examination, the two particles consist of polypoid degenerated structures deriv...
Serotonin-containing cells in the gastrointestinal tract of newborn foals and adult horses. Serotonin (5-hydroxytryptamine, 5-HT), a regulatory amine of mucosal enterochromaffin cells plays an important role in the control of gastrointestinal smooth muscle contraction and epithelial secretion. Serotonin has also been associated with gastric ulcers, diarrhoea and abdominal pain. In spite of the high incidence of these gastrointestinal disorders in newborn foals and adult horses, no data are available regarding 5-HT immunoreactive cells (i.c.) in the gastrointestinal tract (GIT) of foals, and for adult horses, data are incomplete and contradictory. In this study, the distribution and r...
Echocardiographic evidence of an aortico-pulmonary septal defect in a 4-day-old thoroughbred foal. We describe the echocardiographic findings in a 4-day-old thoroughbred foal with an aortico-pulmonary septal defect. The foal had labored breathing, cyanotic mucous membranes and a continuous grade 5/6 heart murmur with point of maximal intensity over the base of the heart on the right side. Echocardiographically, there was a large communication between the aorta and the pulmonary artery just dorsal to the base of the heart. The cardiac anomaly seen during the echocardiographic exam was confirmed at necropsy where a large communication between the two great vessels was observed. These findings...
How does magnetic resonance imaging represent histologic findings in the equine digit? Magnetic resonance (MR) imaging is increasingly used in the diagnosis of equine foot pain, but improved understanding of how MR images represent tissue-level changes in the equine foot is required. We hypothesized that alterations in signal intensity and tissue contour would represent changes in tissue structure detected using histologic evaluation. The study objectives were to determine the significance of MR signal alterations in feet from horses with and without lameness, by comparison with histopathologic changes. Fifty-one cadaver feet from horses with a history of lameness improved by pa...
Magnetic resonance imaging characteristics of the foot in horses with palmar foot pain and control horses. Palmar foot pain is a common cause of lameness. Magnetic resonance imaging (MRI) has the potential to detect damage in all tissues of the equine foot, but an understanding of the differences in magnetic resonance (MR) images between feet from horses with and without palmar foot pain is required. This study aimed to describe MR findings in feet from horses with no history of foot-related lameness, and to compare these with MR findings in horses with lameness improved by palmar digital local analgesia. Thirty-four limbs from horses euthanized with a clinical diagnosis of navicular syndrome (amen...
Catastrophic fracture of the lateral condyle of the third metacarpus/metatarsus in UK racehorses – fracture descriptions and pre-existing pathology. The characteristics of, and pre-existing pathology associated with 75 cases of fatal lateral condylar fracture sustained by Thoroughbreds while racing in the UK were described. Cases were identified from 220 cases of fatal distal limb fracture submitted as part of studies designed to identify risk factors for all fatal distal limb fractures. Fractures were most common in hurdle races and affected the right forelimb twice as often as the left forelimb. Fracture dimensions were similar to previous reports, however there was a much greater prevalence of articular and diaphyseal comminution and of...
Navicular disease: a review of what’s new. The 21st century has heralded a reassessment of our ideas about
navicular disease. In particular, the proposal of different
pathological entities has led to alternative treatment regimes and a
sounder basis for reaching a prognosis. Further, recently generated
data have given grounds for reconsidering both terminology and
treatment. The impact of recent information on the clinical
approach to suspected navicular disease of concepts relating to
diagnostic analgesia, the evolution of diagnostic imaging
techniques, biomarkers, biomechanics and heritability require
placing into the contex...
Histopathology in horses with chronic palmar foot pain and age-matched controls. Part 1: Navicular bone and related structures. Causes of palmar foot pain and the aetiopathogenesis of navicular disease remain poorly understood, despite the high incidence of foot-related lameness. Objective: Abnormalities of the collateral sesamoidean ligaments (CSLs), distal sesamoidean impar ligament (DSIL), deep digital flexor tendon (DDFT), navicular bone, navicular bursa, distal interphalangeal (DIP) joint or collateral ligaments (CLs) of the DIP joint may contribute to palmar foot pain. Methods: Feet were selected from horses with a history of unilateral or bilateral forelimb lameness of at least 2 months' duration that was improv...
Histopathology in horses with chronic palmar foot pain and age-matched controls. Part 2: The deep digital flexor tendon. Causes of palmar foot pain and the aetiopathogenesis of navicular disease remain poorly understood, despite the high incidence of foot-related lameness. Objective: Abnormalities of the deep digital flexor tendon (DDFT) may contribute to palmar foot pain; ageing degenerative changes may be seen in horses free from lameness; and horses with lameness are likely to have a greater severity of abnormalities than age-matched horses with no history of foot pain. Methods: Feet were selected from horses with a history of uni- or bilateral forelimb lameness of at least 2 months' duration. Histology of th...
Mechanical nociceptive thresholds in the axial skeleton of horses. An objective measure of neck, back and croup pain is needed in horses with musculoskeletal injuries, vague upper limb lameness or poor performance. Objective: To establish mechanical nociceptive thresholds (MNTs) within the axial skeleton and evaluate the effects of subject status and ridden exercise. Methods: Thirty-six mature horses (10 nonridden; 26 actively ridden) were used to assess MNTs evoked by a pressure algometer (PA) with a 1 cm2 rubber plunger tip at 62 midline and bilaterally symmetrical anatomical landmarks along the axial skeleton. Pressure was applied at a uniform rate of appl...
Use of scintigraphy for diagnosis of equine paranasal sinus disorders. To describe and analyze subjective and objective scintigraphic findings in horses with paranasal sinus disorders. Methods: Horses with suspected disorders of the paranasal sinuses or cheek teeth (n = 48) and control horses (n = 30). Methods: 99Technetium-methylenediphosphate (99Tc-MDP; 7500 MBq) was administered for scintigraphic examination of the skull. Abnormal patterns of increased radionuclide uptake (IRU) were identified and subjectively described. Scintigrams and radiographs were blindly assessed by 2 clinicians and the accuracy of the imaging modalities was compared. Objective analysis...
In vitro comparison of two techniques for suture prosthesis placement in the muscular process of the equine arytenoid cartilage. To compare in vitro the load necessary for a partial and complete rupture of the muscular process arytenoid cartilage when a suture prosthesis is positioned by a bone trocar versus a trocar point needle and to compare failure mode. Methods: Experimental using cadaver specimens. Methods: Larynges from 18 Thoroughbred race horses, aged 2-20 years. Methods: Arytenoid cartilages were separated randomly into 2 groups: group 1-suture prosthesis inserted directly through the muscular process using a curved trocar point needle and group 2-suture passed through a hole predrilled with a 3 mm bone trocar...
The complex blood supply to the equine testis as a cause of failure in laparoscopic castration. Intra-abdominal ligation/ transection of the spermatic cord may result in necrosis of the testis; castration of abdominal cryptorchids via laparoscopy has therefore become common. Notwithstanding some adaptations of the technique, a small percentage of operations fail, prompting research into the anatomical background and clinical relevance of the procedure. Objective: That an alternate blood supply may prevent complete necrosis of the testis after spermatic cord transection. Objective: To establish the prevalence of the problem in normal and cryptorchid stallions. Methods: In a preliminary st...
Deep digital flexor tendonitis in the equine foot diagnosed by low-field magnetic resonance imaging in the standing patient: 18 cases. Injury to the distal aspects of the deep digital flexor tendon (DDFT) is an important cause of lameness in horses. The purpose of this study was to review the magnetic resonance imaging (MRI) findings of 18 horses affected by DDFT injuries in the foot. The MRI was performed with the horses standing using an open low-field (0.21 T) MRI scanner. The results were compared with those previously reported for horses using high-field MRI. Eighteen of 84 horses (21%) with undiagnosed forefoot pain were found to have lesions affecting the DDFT. The history, clinical findings and results of radiography,...
Subtotal ostectomy of dorsal spinous processes performed in nine standing horses. To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. Methods: Retrospective study. Methods: Nine adult horses. Methods: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. Results: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 becaus...
A new approach for perineural injection of the lateral palmar nerve in the horse. To evaluate the accuracy of a new technique for perineural injection of the lateral palmar nerve and to determine frequency of inadvertent injection into the carpal synovial sheath with this technique. Methods: Prospective experimental study. Methods: Thirty equine cadaver forelimbs. Methods: Each of 3 clinicians injected 0.5 mL of a 1% aqueous solution of new methylene blue as a marker at the medial aspect of the accessory carpal bone of 10 limbs. Immediately after each injection, the lateral palmar nerve was identified by dissection of and inspected for proximity of dye, and the carpal synov...
Treatment of a second carpal bone fracture by removal under ultrasonographic guidance in a horse. To report an unusual 2nd carpal bone (C2) slab fracture and its treatment, using an ultrasonographically assisted, minimally invasive arthrotomy technique, for fragment removal. Methods: Case report. Methods: An 11-year-old crossbred Warmblood gelding. Methods: A bone fragment, spanning the height of C2, identified on the palmaromedial aspect of C2 was demarcated intraoperatively using ultrasonographically guided needles and removed by arthrotomy. Results: Fracture fragment removal was achieved using a small, ultrasonographically guided arthrotomy. The horse has become sound after treatment an...
Measurement of articular cartilage stiffness of the femoropatellar, tarsocrural, and metatarsophalangeal joints in horses and comparison with biochemical data. To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content. Methods: Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location. Methods: Eight equine cadavers (4 intact females, 4 castrated males; ...
Validation of magnetic resonance imaging for measurement of equine articular cartilage and subchondral bone thickness. To validate use of magnetic resonance images (MRIs) for measurement of equine articular cartilage and subchondral bone thickness by comparison with measurements in histologic specimens. Methods: 32 cadaveric carpal joints from 16 horses. Methods: Magnetic resonance imaging was performed by use of 3-dimensional fast spoiled gradient echo (SPGR) and T2* 3-dimensional fast gradient echo (GRE) pulse sequences with and without fat saturation. Standard sites on the medial and lateral facets of the intermediate, radial, and third carpal bones were used for subchondral bone and articular cartilage thi...
Spatial distribution of osteocyte lacunae in equine radii and third metacarpals: considerations for cellular communication, microdamage detection and metabolism. Osteocytes, which are embedded in bone matrix, are the most abundant cells in bone. Despite the ideal location of osteocytes to sense the local environment and influence bone remodeling, their functions, and the relative importance of these functions, remain controversial. In this study, we tested several hypotheses that address the possibilities that population densities of osteocyte lacunae (Ot.Lc.N/B.Ar) correlate with strain-, remodeling- or metabolism-related aspects of the local biomechanical environments of mid-third diaphyseal equine radii and third metacarpals from skeletally mature a...
Distribution of eosinophils and mast cells in the cervical tissue of non-gravid mares during dioestrus. Little is known about the local cellular immune system of the equine cervix. In this study we characterize the distribution of eosinophilic granulocytes and mast cells in the cervical tissue of non-gravid mares during dioestrus. For this purpose cervices of 10 mares were histologically examined after Sirius red and Toluidine blue staining. Both cell types could be found in the lamina propria mucosae. In the tunica muscularis the two cell populations were only rarely detected. No cells could be found in the epithelium mucosae. There was a decreasing cell density from the vaginal to uterine side...
