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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.
Maternal age and parity influence ultrasonographic measurements of fetal growth in Dutch Warmblood mares. Ultrasonographic examination of the equine fetus in mid-late gestation is usually performed only if there are concerns about fetal or maternal health. Even then it is difficult to determine whether development is 'normal' for gestational age because the reference values include considerable error margins. This study examined maternal factors that influence fetal growth with the aim of producing more precise late gestation fetal growth curves for Dutch Warmblood horses. Fetal development was monitored at 2-week intervals from day 100 of gestation until term in 32 mares ranging from 4 to 18 year...
Histological and biomechanical effects of palatal sclerotherapy in the horse using sodium tetradecyl sulfate. Palatal sclerotherapy using sodium tetradecyl sulfate has been suggested as a treatment for dorsal displacement of the soft palate in young Standardbred horses. The present study evaluated histological and biomechanical changes in the equine soft palate following trans-endoscopic treatment with a low dose of this compound. Two horses were euthanased and examined at 2 weeks and at 1, 2, 4 and 6 months post-sclerotherapy, while two further horses served as untreated controls. The technique was easily performed in all cases without major complications. On histological examination there was no evi...
Virtual histology by means of high-resolution X-ray CT. Micro-CT is a non-destructive technique for 3D tomographic investigation of an object. A 3D representation of the internal structure is calculated based on a series of X-ray radiographs taken from different angles. The spatial resolution of current laboratory-used micro-CT systems has come down over the last years from a few tens of microns to a few microns. This opens the possibility to perform histological investigations in 3D on a virtual representation of a sample, referred to as virtual 3D histology. The advantage of micro-CT based virtual histology is the immediate and automated 3D visua...
Expression of cyclooxygenase-2 by equine ocular and adnexal squamous cell carcinomas. To investigate whether cyclooxygenase-2 (COX-2) is expressed by equine ocular and adnexal squamous cell carcinomas (SCC). Methods: Forty-three samples of histologically confirmed cases of ocular SCC or carcinoma in situ (CIS) from 34 horses presented to the Animal Health Trust between 1992 and 2004 were subjected to a standard, two-layered, indirect immunohistochemical method using a rabbit polyclonal antihuman COX-2 antibody. Ten formalin-fixed, paraffin-embedded tissue samples taken from recognized predilection sites for SCC, from the grossly normal eyes of 10 horses euthanized for reasons u...
Serial gastrointestinal ultrasonography following exploratory celiotomy in normal adult ponies. The objective was to characterize ultrasonographic changes in bowel wall thickness, contractility, degree of distension, luminal contents, and peritoneal fluid associated with exploratory celiotomy in normal ponies. Gastrointestinal ultrasonographic examination was performed in 14 ponies on days 1, 3, 5, and 7 after an exploratory celiotomy. Wall thickness, contractility, degree of distension, and luminal contents were recorded for the duodenum and jejunum. Stomach wall thickness and location, cecal wall thickness, and peritoneal fluid location and character were recorded. Peritoneal fluid was...
Imaging diagnosis–avulsion of the origin of the popliteal tendon in a horse. No abstract available
Is a magic angle effect observed in the collateral ligaments of the distal interphalangeal joint or the oblique sesamoidean ligaments during standing magnetic resonance imaging? Collagen fibers oriented at 55 degrees to the static magnetic field (B0) are characterized by an artifactual increase in signal intensity due to the magic angle effect. We hypothesized that there would be increased signal intensity in the collateral ligaments of the distal interphalangeal joint and oblique sesamoidean ligaments when these ligaments were at angles approaching 55 degrees to a horizontal B0 during standing magnetic resonance (MR) imaging. MR imaging was performed on four cadaver forelimbs in a 0.27 T standing system. Transverse and dorsal images were obtained using various sequen...
Magnetic resonance imaging of distal sesamoidean ligament injury. Distal sesamoidean ligament injury is a recognized cause of lameness but diagnosis using ultrasonography is sometimes difficult. Herein, we describe the normal appearance of the distal sesamoidean ligaments on magnetic resonance (MR) images and the changes that occur when the ligaments are injured. The appearance of the distal sesamoidean ligaments on MR images from 66 control horses and 58 horses with distal sesamoidean desmitis were described and the cross-sectional area and signal intensity of the ligaments measured. In control horses, the ligaments had a characteristic appearance and stron...
Biomechanical evaluation of the equine masticatory action: calculation of the masticatory forces occurring on the cheek tooth battery. The forces generated during equine mastication influence the teeth, as well as the periodontium, the jaw bones, the temporomandibular joints and materials used in dental therapy. Due to the limited accessibility of the cheek teeth located farther caudal in the equine oral cavity the measurement of the masticatory forces on these teeth is virtually impossible. The calculation of such forces is an appropriate, indirect alternative to direct measuring. Hence, a mathematical model, which respects several morphological features of the equine dentition, e.g. the Curve of Spee, is presented. The rele...
Stabilization and mobility of the head, neck and trunk in horses during overground locomotion: comparisons with humans and other primates. Segmental kinematics were investigated in horses during overground locomotion and compared with published reports on humans and other primates to determine the impact of a large neck on rotational mobility (> 20 deg.) and stability (< or = 20 deg.) of the head and trunk. Three adult horses (Equus caballus) performing walks, trots and canters were videotaped in lateral view. Data analysis included locomotor velocity, segmental positions, pitch and linear displacements and velocities, and head displacement frequencies. Equine, human and monkey skulls and cervical spines were measured to estimate...
Compliance calibration for fracture testing of anisotropic biological materials. The compliance technique has been used to monitor crack length during fracture and fatigue testing of materials. Difficulties arise when this technique is applied to anisotropic biological materials such as bone. In this tutorial, two different methods of analyzing compliance calibration data are described: the standard ASTM method and a new approach developed by the authors specifically for anisotropic materials. An example is given showing how data from equine cortical bone can be analyzed. In this example, calibration tests were conducted on thirty-six three point bend specimens machined fr...
Computed tomographic anatomy of the temporomandibular joint in the young horse. The equine temporomandibular joint (TMJ) and its surrounding structures can be difficult to investigate in cases with a clinical problem related to the region. Little previous attention has been given either to a computed tomographic (CT) imaging protocol for the joint or an interpretation of the structures displayed in CT images of the normal joint. Objective: To provide a CT atlas of the normal cross-sectional anatomy of the equine TMJ using frozen and plastinated sections as anatomical reference. Methods: Eight TMJs from 4 immature pure-bred Spanish horses were examined by helical CT. Scans...
Morphology of the occlusal surfaces of premolar and molar teeth as an indicator of age in the horse. The purpose of this study was to investigate the use of cheek tooth occlusal surface morphology as an indicator of age in the horse using a blinded cross-sectional design. Twenty horses of varying age, breed and sex were used. Horses of known age (foaling date) were euthanized for reasons other than dental disease. Following disarticulation of the head and sectioning of the mandibles, cheek teeth were cleaned using running water and photographs were taken of each arcade. Using a computer-based program, the total surface area of each premolar and molar, the outer enamel ridge perimeter distance...
Pathological studies of cheek teeth apical infections in the horse: 2. Quantitative measurements in normal equine dentine. Measurements of primary, regular and irregular secondary dentine and pulp dimensions were made on transverse, sub-occlusal and mid-tooth sections, of 40 maxillary and 42 mandibular control equine cheek teeth (CT) of different ages. Maxillary and mandibular CT primary dentine in different age groups had a mean thickness of 922-1,065 microm and 1099-1,179 microm, respectively, on the lateral aspects, and 1,574-2,035 microm and 1155-1,330 microm, respectively, on the medial aspects of pulp horns. Surprisingly, some increase in thickness was found in some mandibular CT primary enamel in the first ...
Pathological studies of cheek teeth apical infections in the horse: 5. Aetiopathological findings in 57 apically infected maxillary cheek teeth and histological and ultrastructural findings. Examination of 57 apically infected maxillary cheek teeth (CT) showed one or more viable pulps and minimal apical calcified tissue changes present in recently infected CT. With chronic infections, pulps were necrotic or absent, pulp horns were filled with food if occlusal pulpar exposure was present, and gross caries of dentine was occasionally present. With chronic infections, the apical changes varied from gross destructive changes in some teeth, to extensive proliferative calcified apical changes in others. Infundibular caries was believed to cause apical infection in just 16% of infected (...
Pathological studies of cheek teeth apical infections in the horse: 4. Aetiopathological findings in 41 apically infected mandibular cheek teeth. Examination of 41 extracted, apically infected mandibular cheek teeth (CT) without obvious causes of infection included radiography, computerised axial tomography and decalcified and undecalcified histology. In CT with recent infections, some pulps remained viable, with proliferative soft and calcified tissue changes confined to the apex. With more advanced CT infections, occlusal pulpar exposure was sometimes present (in 34% of the 41 CT), some infected pulp chambers were filled with necrotic pulp or food, and extensive destructive or proliferative changes were present in the calcified apical...
Pathological studies of cheek teeth apical infections in the horse: 1. Normal endodontic anatomy and dentinal structure of equine cheek teeth. Morphological examinations were performed on 100 normal equine cheek teeth (CT) of 1-12 years dental age (i.e. time since eruption), using gross examination, dissection microscopy, computerised axial tomography, and decalcified and undecalcified histology. The CT in Triadan 07-10 positions consistently had five pulp horns, but the 06 CT had an additional pulp horn more rostrally. Mandibular and maxillary Triadan 11s had six and seven pulp horns, respectively. Sections of CT taken 2-6mm below the occlusal surface (variation due to normal undulating occlusal surface) showed the presence of pulp ...
Equine odontoclastic tooth resorption and hypercementosis. A poorly described, painful disorder of incisor and canine teeth, variably causing periodontitis, with resorptive or proliferative changes of the calcified dental tissues, has recently been documented in aged horses. No plausible aetiopathogenesis for this syndrome has been recorded. Eighteen diseased teeth from eight horses were examined grossly and microscopically and showed the presence of odontoclastic cells by tartrate resistant acid phosphatase (TRAP) staining. A chronological sequence of odontoclastic resorption followed by hypercementosis was demonstrated and, consequently, the term eq...
Prevalence of occlusal pulpar exposure in 110 equine cheek teeth with apical infections and idiopathic fractures. Examination of 110 cheek teeth (CT) that were clinically extracted (between 2004 and 2008) because of apical infection (n=79; mean dental age 3.5 years) or idiopathic CT fractures (n=31; median dental age 8.5 years), including examinations of transverse and longitudinal sections, showed the apical infections to be mainly (68%) due to anachoresis, with the residual cases caused by periodontal spread, infundibular caries spread, fissure fractures and dysplasia. The idiopathic fracture patterns were similar to previously described patterns. Occlusal pulpar exposure was found in 32% of apically in...
Ocular toxicity and distribution of subconjunctival and intravitreal rapamycin in horses. In vitro photosensitivity of rapamycin (RAPA) and ocular toxicity and distribution of intravitreal and subconjunctival RAPA was evaluated in normal horses. RAPA (2.5 mg, 5 mg, and 10 mg) was placed in 10 mL of PBS and maintained in a water bath at 37 degrees C, kept in the dark or subjected to room light, and sampled for up to 3 months for RAPA levels. Six normal adult horses received either 5 mg (n = 2) or 10 mg (n = 2) of RAPA intravitreally or 10 mg (n = 2) subconjunctivally. Ophthalmic exams and electroretinography (ERG) were performed prior to injection and on days 1, 7, 14, and 21 post-i...
Bilateral testicular mixed germ cell-sex cord-stromal tumours in a stallion. An 18-year-old Friesian stallion was examined approximately one week after reportedly presenting scrotal swelling due to torsion of the spermatic cords. Upon presentation no scrotal swelling was noted, the testes were normally oriented, and no abnormalities of the spermatic cords were noted. However, both testes were smaller than expected for a mature stallion and deep palpation revealed that the consistency of the testes was nodular. Ultrasonographic evaluation of the testes revealed diffuse heterogeneous parenchyma with multiple hypoechoic nodular areas. Grossly, the testicular parenchyma wa...
Fibropapilloma of the glans penis in a horse. An 18-year-old Arabian stallion was presented for recent onset of stranguria. Physical examination of the distal portion of the glans penis revealed multiple, smooth, glistening, grayish-pink, variably sized, exophytic, nodular masses circumferentially surrounding the external urethral orifice. Partial penile amputation was performed, and the entire specimen was submitted for histological evaluation. Microscopically, the masses consisted of abundant amounts of loosely arranged fibrovascular stroma with low numbers of spindloid to stellate fibrocytes. The overlying epithelium was mildly to mode...
Gross anatomy of the female genital organs of the domestic donkey (Equus asinus Linné, 1758). Although donkeys play an important role as companion or pack and draught animals, theriogenological studies and anatomical data on the genital organs of the jenny are sparse. To provide anatomical descriptions and morphometric data, the organa genitalia feminina, their arteries and the ligamentum latum uteri of 10 adult but maiden jennies were examined by means of gross anatomical and morphometric techniques. In comparison with anatomical data of horses obtained from literature the genital organs of jennies appear to be more voluminous in relation to the body mass and the position of the ovari...
Structural characterization of subchondral bone in the distal aspect of third metacarpal bones from Thoroughbred racehorses via micro–computed tomography. To characterize the microstructure of subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the condyles of third metacarpal bones (MC3s) from Thoroughbred racehorses at 2 different stages of SCB disease via micro-computed tomography (CT). Methods: 12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons. Methods: MC3s were collected from horses with mild (n = 6) or severe (6) SCB disease, as determined via micro-CT. Cubic (6 x 6 x 6-cm) specimens of SCB plate and TBB were cut from the palmar aspect of condyles and sagittal ridges and examined ...
Pathological studies of cheek teeth apical infections in the horse: 3. Quantitative measurements of dentine in apically infected cheek teeth. Histological measurements of dimensions of primary, regular secondary and irregular secondary dentine, pulp diameter and assessment of the levels of predentine, resting lines and enlarged areas of intertubular dentine were performed in apically infected mandibular and maxillary cheek teeth (CT). These examinations showed significantly reduced regular and irregular secondary dentine thickness in diseased as compared to control CT, with 21/26 infected maxillary CT and 15/18 infected mandibular CT having reduced regular secondary dentine (varying between 27.4% and 89.1% reduced secondary dentine ...
Primary unilateral fibroleiomyoma of the ovary in a pregnant mare: a case report. Fibroleiomyomas of the ovary are rare. This smooth muscle tumour may develop and increase in size during pregnancy. Diagnosis is based on histological and immunohistochemical analyses. Histologically, the ovarian fibroleiomyoma consists of non-invasive bundles of smooth muscle cells that synthesize collagen-like extracellular matrix. This case report describes an ovarian fibroleiomyoma in a pregnant multiparous broodmare with a history of intermittent signs of colic.
Conservative management of a distal epiphyseal metacarpal fracture in a skyros pony. Epiphyseal fracture, also known as epiphysiolysis, is the loosening or separation, either partial or complete, of an epiphysis from the shaft of a long bone. Distal epiphyseal fractures in foals pose a substantial challenge due to their guarded prognosis. This report describes the clinical signs, diagnosis, successful conservative treatment of an 1-month-old, male Skyros pony with an epiphyseal fracture of the right third metacarpal bone (type II Salter-Harris). The owner declined surgical treatment because of financial considerations along with the unfavorable prognosis. Conservative fracture...
Immunohistochemical characterization and quantitative analysis of neurons in the myenteric plexus of the equine intestine. The present study was performed on whole-mount preparations to investigate the chemical neuroanatomy of the equine myenteric plexus throughout its distribution in the intestinal wall. The objective was to quantify neurons of the myenteric plexus, especially the predominant cholinergic and nitrergic subpopulations. Furthermore, we investigated the distribution of vasoactive intestinal polypeptide and the calcium-binding protein calretinin. Samples from different defined areas of the small intestine and the flexura pelvina were taken from 15 adult horses. After fixation and preparation of the ti...
