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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.
Effect of exercise on bone density in distal regions of the equine third metacarpal bone in 2-year-old thoroughbreds. The present study addressed the question of whether training induces changes in bone density in the younger racehorse in regions relevant to the genesis of the common sagittal condylar fracture pattern and, if so, the nature of such alteration. Third metacarpal bones (McIII) were obtained from 12 experimental Thoroughbred, unbroken fillies, age 18.1-21.0 months at entry to the study. Six (Group E) undertook 19 weeks of progressive high intensity exercise on a high-speed treadmill at 3% incline. Six (Group C) walked 40 min each day. Clinical bone density was studied by Computed Tomography (CT) ...
Osteoinductive response in the dorsal aspect of the carpus of young thoroughbreds in training occurs within months. Bone mineral density (BMD) was measured by dual x-ray absorptiometry (DXA) in the carpus of 6 Thoroughbreds age 24 months that were exercised on the treadmill for 4.5 months, and of 6 matched control horses. A sagittal slab of known thickness was sawn from one or more of radius, radial carpal (Cr), third carpal (C3), and third metacarpal (Mc3) bones. After the 4.5 month treadmill exercise, there was a significantly greater volumetric BMD in the dorsal aspect of C3 (P = 0.006). Treadmill-exercised horses also had higher BMD in the dorsodistal aspect of the radius (P = 0.03), the dorsal half of ...
Standardisation of muscular biopsy of gluteus medius in French trotters. Morphometric measurements were taken from 41 French trotters of various ages and both sexes. Biopsy location was determined for the dorsal compartment as being one-third of the distance from the tuber sacrale to the tuber coxae and for the ventral compartment as being one-third of the distance from the tuber coxae to the caudal Cd1-Cd2 intervertebral joint. Ten horses were biopsied at these 2 sites at a sampling depth equal to half the total depth of the compartment as measured by ultrasonography. The percentage of slow and fast myosin heavy chain fibres was measured by using an immunoenzymati...
In vitro transmission and attenuation of impact vibrations in the distal forelimb. An in vitro model was developed and validated in vivo to quantify the attenuation of impact vibrations, transmitted through the lower equine forelimb and to assess the effects of horseshoeing on this attenuation. The transsected forelimbs of 13 horses were equipped with custom-made hollow bone screws in the 4 distal bones, on each of which a tri-axial accelerometer could be mounted. The limbs were then preloaded while the impact was simulated by dropping a weight on the steel plate on which the hoof was resting. At the hoof wall, the distal, middle and proximal phalanx and at the metacarpal bo...
Radiographic measures of bone shape in young thoroughbreds during training for racing. The aim of this study was to determine if changes in the shape of the third metacarpal bone (MC3) during the first preparation for racing in young Thoroughbred racehorses could be measured radiographically. Lateral radiographs of each MC3 were taken when the horses commenced training, every 2 weeks for 10 weeks, and again at 6 months after the start of training. The width of the dorsal cortex (DC), palmar cortex (PC), and medulla (M) were measured at a position 2.5 cm distal to the nutrient foramen before the subject of each radiograph was identified. The following ratios were calculated: z = ...
[Functional morphology of the large intestinal mucosa of horses (Equus przewalskii f. caballus) with special regard to the epithelium]. The mucous membrane of the caecum and colon ascendens of adult horses was first studied using light and transmission electron microscopy. In the surface epithelium there was an inconspicuous constellation of organelles, otherwise there was a lot of mitochondria as a source of energy for absorptive performances. Moreover, enlarged intercellular spaces exist as an indication of an increased uptake of water and electrolytes. In the basal region of Lieberkühn's crypts there were single enteroendocrine cells and numerous granules in the apical epithelial cytoplasm. The functional meaning of these ...
The teeth of the horse: evolution and anatomo-morphological and radiographic study of their development in the foetus. The aim of this work was to study the ontogenetic process in teeth from their early appearance in the ossifying matrix of the mandible and maxilla, in different foetuses of scalar ages. Radiographic examinations of the skull and mandible hemisections were performed and the latero-medial (LM) and dorsoventral (DV) projections for the skull and mandible were analysed. A high-definition film-screen combination was used for this study. The exposure values ranged from 35 kV/6 mAs to 58 kV/10 mAs, according to the size of the skulls and their degree of ossification. The first dental germ observed wa...
Sonographic observations of the peripheral vasculature of the equine thoracic limb. Investigations of the equine peripheral vascular system have been constrained by the lack of a non-invasive method of examining the arteries and veins of the limbs of the conscious horse. Precise correlations were established between the gross anatomical features of the peripheral vessels and their B-mode sonographic appearance in each thoracic limb of 35 horses. A sonographic imaging protocol was established. Additional Doppler sonographic recordings defined the arterial waveforms and demonstrated that blood flow to the foot could be evaluated in the lateral proper digital artery, distal to t...
The effect of compacted cancellous bone grafting on the healing of subchondral bone defects of the medial femoral condyle in horses. To compare the quality of second-intention healing and that of compacting sternally harvested cancellous bone into subchondral bone defects of the medial femoral condyle in horses. Methods: A controlled experiment using a surgical technique that minimizes soft tissue trauma, customized for consistency among horses. Methods: Ten horses, aged 2 to 5 years, free of hindlimb lameness and with radiographically normal stifles. Methods: After a 12.7-mm-diameter x 19-mm-deep defect was created into randomly selected medial femoral condyles, bone and cartilage healing was evaluated over a 6-month perio...
Age-related morphometry of equine incisors. In the present study the age-related morphological characteristics of 948 equine incisors were investigated. After extraction, total incisival length and root length were measured at the vestibular side of the teeth. Equine incisors reach their maximal length 2-3 years after eruption. Notwithstanding severe occlusal wear, this maximal length is maintained during most of the horses' life due to prolonged root formation. Root formation, at the rate of 2.5 mm per year, starts at the age of 5-6 years and continues until the age of 17. As the root of the incisor develops, its apical foramen narrows...
Evaluation of equine fetal growth from day 100 of gestation to parturition by ultrasonography. Transrectal and transabdominal ultrasonography were performed on normal pregnant mares (n=10) at 2 week intervals from day 100 of gestation to parturition to evaluate fetal growth. Several fetal anatomical regions (head, eye, aorta, abdomen, rib, gonad, kidney and femur) were imaged and measured using standardized scan plans. The results of these analyses indicate that all of the biometric parameters correlate strongly with the day of gestation. Growth charts were developed, which demonstrate that the following variables have linear relationships with the day of gestation on which they were me...
Development of equine endometrial glands from fetal life to ovarian cyclicity. Branched tubular endometrial glands are key features of the uterine lining in mares. The epithelium in the neck regions of the glands is similar to that lining the lumen of the uterus, whereas the epithelium in the deeper, coiled portions of the glands secretes protein rich histotrophe or 'uterine milk' during dioestrus and pregnancy. The present study was performed to characterize endometrial histology in perinatal and peripubertal fillies and to investigate the influences of specific steroid treatments on endometrial gland development in the prepubertal period. Uteri obtained from equine fet...
Simultaneous exocrine and endocrine secretion: trophoblast and glands of the endometrial cups. Invasion of trophoblast cells of the chorionic girdle into the endometrium and their subsequent dependence as endometrial cup cells on the maternal vascular system are unique features of equine gestation. This study of exocrine secretion by the endometrial glands and endocrine secretion by the cup cells was initiated to examine the relationships between and the effects of two disparate epithelial cell types sharing the endometrium. Endometrial cups were examined from day 36 to day 83 of gestation by light and electron microscopy, and immunohistochemical and lectin analysis. As the cup cells in...
The distribution of nerve fibres immunoreactive for vasoactive intestinal peptide, calcitonin gene-related peptide, substance P and dopamine beta-hydroxylase in the normal equine larynx. The autonomic innervation of the mammalian respiratory system is complex, and involves a wide variety of peptide and non-peptide neurotransmitters which will have an important role in normal laryngeal function and the response to disease. This innervation has been partially described in the horse airway and lung, but there is no information on the equine larynx. This paper describes the expression and distribution of nerve fibres immunoreactive for vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), substance P (SP) and the adrenergic enzymatic marker dopamine beta-hyd...
Equine dental disease part 2: a long-term study of 400 cases: disorders of development and eruption and variations in position of the cheek teeth. Of 400 referred horses with dental disorders, 349 cases suffered from primary disorders of their cheek teeth, ninety of these from disorders of development or eruption, or displacements. These included 20 cases with rostral maxillary and caudal mandibular cheek teeth overgrowths, 16 with diastemata, 15 with grossly enlarged mandibular 'eruption cysts', 4 with grossly enlarged maxillary cheek teeth 'eruption cysts', 10 cases with supernumerary cheek teeth and 23 cases with displaced cheek teeth. These displacements were believed to be developmental in 16 cases and acquired in the remaining 7 ca...
Radiological study to evaluate suspected scapulohumeral joint dysplasia in Shetland ponies. A radiological study was performed to test the hypothesis that osteoarthritis of the scapulohumeral joint in Shetland ponies is secondary to shoulder dysplasia. Animals were selected into 3 groups: Group 1: Shetland ponies with a radiological and clinical diagnosis of scapulohumeral osteoarthritis (n = 8); Group 2: Shetland ponies without forelimb lameness (n = 12); Group 3: Horses/ponies without a history or clinical signs of forelimb lameness (n = 22). Anatomical indices were measured from mediolateral radiographs of a scapulohumeral joint from each animal. There was a significant difference...
In vitro mechanical properties of different equine hoof wall crack fixation techniques. Hoof wall cracks need mechanical stabilisation to allow healing. Common techniques are fixation with screws, wires and plates or bonding of a patch across the crack. An in vitro system to determine the shear properties of equine hoof crack repairs is described. The force and displacement at yield, stiffness and ultimate force were determined for 4 repair techniques based on an acrylic material, polyurethane patch attached with cyanoacrylate adhesive, steel plate attached with screws and a transverse metal bar cut into the hoof wall. The cyanoacrylate bonded patch repair had lower values for al...
Transabdominal ultrasonographic determination of fetal gender in the horse during mid-gestation. Gender determination of the equine fetus using transabdominal ultrasonography was studied in 20 mares. One group of 10 research mares was scanned repeatedly every 2 weeks from 100 days gestation to parturition, while the second group of 10 client mares was subjected to echography once during mid-gestation. In males, the penis and/or prepuce was observed on 71 occasions from 102 days to 258 days gestation. On cross-sectional views, the male external genitalia had a round shape with parallel linear echogenic foci up to approximately 140 days gestation and then appeared triangular. Fetal testes w...
Surgical repair of a thoracic meningocele in a foal. A 6 week old American Paint filly was admitted for evaluation of a dorsal thoracic mass suspected to be a meningocele. The diagnosis was confirmed by plain and contrast enhanced computed tomography. Surgical repair was performed by dissection of the base of the meningocele followed by ligation. No postoperative complications occurred. Contrast enhanced computed tomography was useful to confirm the diagnosis of meningocele and rule out a meningomyelocele.
Comparison of incisional bursting strength of simple continuous and inverted cruciate suture patterns in the equine linea alba. To determine the bursting strength of ventral median abdominal incisions closed by either simple continuous or inverted cruciate suture patterns. Methods: Experimental. Methods: Twelve equine cadavers. Methods: A 25 cm ventral median incision was made through the linea alba and a 200 L polyurethane bladder was placed within the abdomen. Either a simple continuous or an inverted cruciate pattern using 3 polyglactin 910 with a bite size and suture interval of 1.5 cm was used to close linea incisions. Closure time was recorded for each pattern. The bladder was inflated with air at 40 L/min, and t...
Anatomic, radiographic and physiologic comparisons of the internal carotid and maxillary artery in the horse. The anatomy of the internal carotid and maxillary arteries was examined using angiography, subtraction angiography and arterial cast preparations in three horses. Subtraction angiography was superior to angiography in demonstrating the anatomy of the occipital, external ophthalmic, ethmoidal and palatine arteries. In three horses manipulation of the internal carotid and occipital arteries during angiography resulted in vasospasm which prevented filling of these vessels with contrast. Direct arterial blood pressure measurements of the maxillary artery impinging on the guttural pouches was measu...
CT examination of the guttural pouch (auditory tube diverticulum) in Przewalski’s Horse (Equus przewalskii). The domestic horse (Equus caballus) have the large symmetrical guttural pouches (the auditory tube diverticulum) formed by saccate bulge of the auditory tube. In this study, CT examination was carried out in the head of Przewalski's horse (Equus przewalskii), the only true wild horse living at present. As results of the examination, Przewalski's horse possessed the large symmetrical guttural pouches divided into medial and lateral compartments by the stylohyoid bone. Moreover, the right and left guttural pouches meet each other at the median part to form a thin septum. As CT sections get close...
Structure of oxalate-substituted diferric mare lactoferrin at 2.7 A resolution. Lactoferrin binds two Fe(3+) and two CO(2-)(3) ions with high affinity. It can also bind other metal ions and anions. In order to determine the perturbations in the environments of the binding sites in the N and C lobes and elsewhere in the protein, the crystal structure of oxalate-substituted diferric mare lactoferrin has been determined at 2.7 A resolution. The final model has a crystallographic R factor of 21.3% for all data in the resolution range 17.0-2.7 A. The substitution of an oxalate anion does not perturb the overall structure of the protein, but produces several significant changes...
The dorsoproximal-dorsodistal projection of the distal carpal bones in horses: an evaluation of different beam-cassette angles. To estimate the extent of the third carpal bone (C3) visible for evaluation in the dorsoproximal-dorsodistal oblique projection of the distal row of carpal bones, 13 forelimbs collected at post mortem from 7 horses were examined radiographically. The limbs were frozen with the carpal joints flexed then radiographed using fixed beam-cassette angles of 15 degrees to 45 degrees, at 5 degree intervals. The influence of beam-cassette angle on; the depth of the proximal articular surface examined, the radiographic appearance of C3 and the assessment of subchondral sclerosis was evaluated. Beam-casse...
