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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.
Tubular contents of equine dentin: a scanning electron microscopic study. The dentinal tubules of 20 permanent equine incisors were investigated by scanning electron microscopy. Occlusal surfaces and longitudinal fracture planes of both etched and undecalcified teeth were examined. Three different types of structure were observed inside the dentinal tubular lumen. Odontoblastic processes could only be visualized in the circumpulpal parts of the tubules. The more peripheral parts were empty or housed cylindrical structures that probably correspond to the laminae limitantes. Collagen fibres were frequently observed in the tubular lumina and were most numerous in the c...
Stereological estimation of volume-weighted mean glomerular volume from arbitrary sections of the equine kidney. Mean glomerular volume has previously been estimated, using stereological techniques, specifically the point-sampled intercept (PSI), either from isotropic or from vertical sections. As glomeruli are approximately spherical structures, the same stereological technique was carried out on vertical and arbitrary sections to determine whether section orientation had any effect on mean glomerular volume estimation. Equine kidneys from 10 individuals were analysed using the PSI method of estimating volume-weighted mean glomerular volume (MGV); for each kidney, arbitrary and vertical sections were an...
The effect of exercise on the distribution and manifestation of osteochondrotic lesions in the Warmblood foal. Osteochondrosis (OC) in the horse has been defined as a disturbance in the process of endochondral ossification which is of multifactorial origin, becoming evident in a large number of joints. Exercise is one of the environmental factors that may influence the clinical manifestation of the disorder, but has never been thoroughly investigated. In this study we investigated the influence of exercise during the first 5 months on the development and distribution of OC lesions in foals of age 5 and 11 months. Forty-three foals, all from sires having OC in either the femoropatellar or tibiotarsal jo...
Histological and morphometrical studies on the mucosa of the equine guttural pouch (auditory tube diverticulum). The present study attempted to clarify the characteristics of the guttural pouch mucosa in equines and to evaluate its foreign substance clearance ability. The specimens were collected from nine regions (eight in the guttural pouch mucosa, and one in the nasopharynx mucosa). We first examined the pouch mucosa by light and electron microscopy. We then measured the frequency of goblet cells per 200 epithelial cells, the length of the cilia, the thickness of the epithelial cell layer and lamina propria and statistically analyzed the data. The guttural pouch mucosa consisted of stratified columnar...
The influence of birth weight, rate of weight gain and final achieved height and sex on the development of osteochondrotic lesions in a population of genetically predisposed Warmblood foals. The influence of inherent variables (sex, birth weight, final achieved height, monthly weight gain rates and osteochondrosis (OC) status of the parents) on the occurrence of osteochondrotic lesions in the femoropatellar and tarsocrural joints in a group of foals was investigated as part of a research project aimed at the study of the development of osteochondrosis and the influence of exercise on the development of the musculoskeletal system in Warmbloods. The foals were genetically predisposed to develop OC, being offspring of sires that all had radiographically proven OC in either the femoro...
Radiographic development of osteochondral abnormalities, in the hock and stifle of Dutch Warmblood foals, from age 1 to 11 months. In a longitudinal study the hocks and stifles of Dutch Warmblood foals were radiographed at age 1 month and subsequently at intervals of 4 weeks. Forty-three foals were radiographed until age 5 months and 19 foals until age 11 months. The chance for the development of osteochondrosis was enhanced by using only offspring from diseased sires with radiographically proven OC at either the intermediate ridge of the distal tibia or the lateral ridge of the femoral trochlea. The radiographic appearances of the intermediate ridge of the distal tibia, the distal aspect of the lateral trochlear ridge of...
Transarterial coil embolization of the internal and external carotid and maxillary arteries for prevention of hemorrhage from guttural pouch mycosis in horses. To develop a transarterial coil embolization technique for occlusion of the internal carotid artery (ICA), external carotid artery (ECA), and maxillary arteries (MA) in normal horses and to evaluate this technique for prevention of hemorrhage in horses affected with guttural pouch mycosis. Methods: Ten adult, normal horses and 4 horses with guttural pouch mycosis. Methods: All horses had transarterial coil embolization of the rostral and caudal ICA, caudal MA, and rostral ECA. In 1 affected horse, an aberrant actively bleeding branch of the ECA was also occluded. Normal horses had a premortem ...
Postnatal muscle fibre composition of the gluteus medius muscle of Dutch Warmblood foals; maturation and the influence of exercise. The fibre type composition of the deep gluteus muscle was studied in biopsies of Dutch Warmblood foals from birth until age 48 weeks. Half the foals were given box-rest, the other half received exercise consisting of an increasing number of gallop sprints. The muscle fibre types were determined using monoclonal antibodies discriminating against the following myosin heavy chain (MHC) isoforms: types I, IIa, IId, Cardiac-alpha and Developmental. During the first 48 weeks there was a consistent increase of fibres expressing types IIa MHC, replacing fibres expressing IId MHC. This change was refle...
Fetal maceration and retention of fetal bones in a mare. A 19-year-old Quarter Horse mare was evaluated because of bloody vaginal discharge that was apparent immediately following breeding. On transrectal ultrasonography, it was evident that the uterus was filled with fluid containing echogenic particles; linear hyperechoic structures were also visible. Endoscopy was performed, which revealed a number of bones adhered to the cranial wall and floor of the right uterine horn as well as purulent fluid in both uterine horns. Bacterial endometritis and fetal maceration were diagnosed. The mare was treated with antibiotics, and the fetal bones were manual...
Functional morphology of the equine pelvic flexure and its role in disease. A review. The hindgut is the major site in the horse for nutrient digestion and absorption. Most of this activity occurs in the large intestinal compartments, i.e., cecum, right and left ventral colon and left and right dorsal colon. The colonic pelvic flexure is a short and narrow loop connecting the left ventral and left dorsal colon. It is not significant directly in digestive and absorptive processes but plays an important functional role in regulating colonic aboral and retropropulsive transit of digesta through its motility pacemaker activity. The pelvic flexure also contributes to the pathophysio...
Magnetic resonance imaging and cross sectional anatomy of the normal equine sinuses and nasal passages. The purpose of this investigation was to define the magnetic resonance imaging anatomy of the rostral part of the equine head. 10 mm-thick, T1-weighted images of two isolated equine cadaver heads were obtained using a 1.5 Tesla magnet and a body coil. MR images were compared to corresponding frozen cross-sections of the cadaver head. Relevant anatomic structures were identified and labeled at each level. The resulting images provided excellent anatomic detail of the oral and nasal cavities, paranasal sinuses and associated structures. Annotated MR images from this study are intended as a refer...
Closure of the abdominal wall at the umbilicus and the development of umbilical hernias in a group of foals from birth to 11 months of age. The closure of the body wall defect at the umbilicus was studied in relation to the development of umbilical hernias in a group of 44 normal foals, 25 of which were followed from birth until five months of age, and 19 from birth until 11 months of age. At birth, 19 of the foals had a defect in the body wall at the umbilicus that was termed a 'palpable umbilical ring'. In 18 of them this defect disappeared within four days, but in the other the ring did not close and a hernial sac with abdominal contents was palpable. This foal was considered to be the only foal to have a truly congenital umbil...
Characterization and distribution of gonadotrophs in the pars distalis and pars tuberalis of the equine pituitary gland during the estrous cycle and seasonal anestrus. Little is known about the neuroendocrine control of fertility in the horse. In this species, unusual features characterize the normal estrous cycle such as a prolonged preovulatory LH surge during the follicular phase and a distinctive FSH surge during the midluteal phase. This study investigated the distribution and hormonal identity of gonadotrophs in the pars distalis (PD) and pars tuberalis (PT) of the equine pituitary gland as possible morphological bases for the referred unusual endocrine characteristics. In addition, the proportion of gonadotrophs in relation to other pituitary cell typ...
The forelimb in walking horses: 2. Net joint moments and joint powers. The objective was to measure the net joint moments and joint powers for the joints of the equine forelimb during the walk. Videographic and force data were combined with morphometric information using an inverse dynamics method. During stance phase the predominant joint moment was on the palmar aspect of all forelimb joints except the shoulder, where the peak moment was considerably higher than at any other joint. The entire forelimb showed net energy absorption in both stance and swing phases. The elbow was the only joint that showed net generation of energy, which was used to maintain the li...
The forelimb in walking horses: 1. Kinematics and ground reaction forces. Video (60 Hz) and force (2000 Hz) data were collected from 5 sound horses during walking. Forelimb data were analysed for 8 strides (4 left, 4 right) per horse to determine sagittal plane kinematics and ground reaction forces (GRFs). The results suggested that brachial rotation was responsible for protraction and retraction of the limb as a whole, while rotations of the scapula and antebrachium elevated the distal limb during breakover and early swing then lowered it in preparation for ground contact. The coffin joint was flexed maximally at the time of peak longitudinal braking force, which o...
Scanning electron microscopy of the microcotyledonary placenta of the horse (Equus caballus) in the latter half of gestation. Scanning electron microscopy was used to examine the microstructure of the maternal and fetal placenta from 25 pregnant ponies (Equus caballus) throughout the second half of gestation. Samples of placenta, 2-6 cm(2)in area, were collected from the antimesometrial region of the pregnant horn at 105 days (n=1), 165-219 days (n=5), 260 days (n=3), 270-277 days (n=3), 313-337 days (n=11) and immediately after spontaneous delivery at term (n=2). The maternal microcaruncle appears to be created from a clustering of about 16 uterine crypts encapsulated in a connective tissue sheath. There is a gestat...
A unique exocelom-like space during early pregnancy in the horse. The free allantois and allantochorion of conceptuses from 17 mares between 20 and 90 days of gestation were examined to determine the manner in which the associated mesodermal derivatives differentiated. It was found that a robust basement membrane developed under the allantoic endoderm, and that this basement membrane was partially isolated from the vascular layer of the allantois by a mesothelial layer and an exocelom-like space. The exocelom-like space persisted until approximately the stage of villous formation, and remnants of the space persisted over larger allantoic vessels even later. ...
Light and scanning electron microscopic studies of the nasal turbinates of the horse. The nasal turbinates of 5 young horses were studied by light and scanning electron-microscopy. Stratified cuboidal epithelium lined the rostral part of the dorsal and ventral nasal turbinates of the vestibular region. The polyangular microvillus cells of this region were separated by linear depressions. The mid and caudal parts of the dorsal and ventral nasal turbinates and the rostral part of the ethmoturbinates were lined by pseudostratified columnar ciliated respiratory epithelium. Numerous cilia with dilated blebs on the ciliated cells concealed adjacent non-ciliated supporting cells and g...
Fine structure of the retinal pigment epithelium, Bruch’s membrane and choriocapillaris in the horse. The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in both the tapetal and non-tapetal fundus of the horse eye. In all locations, the RPE consisted of a single layer of low cuboidal cells. The epithelial cells were joined laterally by apically located tight junctions. These cells displayed numerous basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large and located basally. Within the epithelial cells, smooth endo...
In vitro biomechanical properties of 2 compression fixation methods for midbody proximal sesamoid bone fractures in horses. To evaluate 2 methods of midbody proximal sesamoid bone repair--fixation by a screw placed in lag fashion and circumferential wire fixation--by comparing yield load and the adjacent soft-tissue strain during monotonic loading. Methods: Experimental study. Methods: 10 paired equine cadaver forelimbs from race-trained horses. Methods: A transverse midbody osteotomy of the medial proximal sesamoid bone (PSB) was created. The osteotomy was repaired with a 4.5-mm cortex bone screw placed in lag fashion or a 1.25-mm circumferential wire. The limbs were instrumented with differential variable relucta...
An in vitro comparison of cordopexy, cordopexy and laryngoplasty, and laryngoplasty for treatment of equine laryngeal hemiplegia. To examine the effect of cordopexy, laryngoplasty, and cordopexy combined with a modified laryngoplasty on airway mechanics. Methods: Experimental airway mechanics were determined by subjecting equine cadaveric larynges to airflows similar to inspiratory airflow of exercising horses. Methods: Twenty equine larynges. Methods: Using cadaveric larynges, we developed and tested a new technique of arytenoid cartilage abduction. All larynges had the right arytenoid cartilage abducted to mimic the degree of arytenoid abduction that occurs at maximal exertion in live horses. Three surgical techniques ...
Sternal bone biopsy in standing horses. To develop a technique for sternal bone biopsy in standing horses. Methods: Experimental study. Methods: Five adult horses. Methods: Horses were restrained in a standing stocks and sedated. The sternal biopsy site, identified by ultrasonographic examination, was clipped and prepared for aseptic surgery and infiltrated with local anesthetic. An electric bone biopsy drill (Osteocore; Institut Straumann AG, CH-4437, Waldenburg, Switzerland)), which yielded 4-mm-diameter bone specimens, was used to obtain sternal biopsies through a small skin incision. Sections (7 microm) of the bone specimens wer...
Effect of age on immunocytochemical staining characteristics of adenohypophyseal cells in Mongolian pony mares and stallions. To determine the effect of age on immunocytochemical staining characteristics of adenohypophyseal cells of Mongolian pony mares and stallions. Methods: 35 Mongolian ponies. Methods: Pituitary glands from 1- to 22-year-old horses of both sexes were collected at a commercial slaughterhouse in China and allocated into 7 groups according to age and sex: prepubertal stallions (n = 5; 1 to 2 years old), young stallions (6; 3 to 7 years old), middle-aged stallions (4; 10 to 12 years old), old stallions (5; 15 to 22 years old), young mares (3; 3 to 7 years old), middle-aged mares (5; 10 to 12 years ol...
Cytochemical and electrophoretic study of the stallion epididymal glycoproteins. It has been suggested that proteins produced in specific regions of the epididymis, mostly androgen dependent glycoproteins, are involved in the sperm maturation process. In the present work, the glycoconjugated distribution pattern and the electrophoretic characteristics of the stallion epididymal proteins were examined using lectin probes. The identification in the luminal fluid of some new proteins, probably synthesized and secreted by the epididymis, is an important initial step to investigate their interaction with the stallion sperm membrane. The binding of FITC-lectins (ConA, WGA, LPA, ...
Comparison of bone healing by demineralized bone matrix and autogenous cancellous bone in horses. The purpose of this study was to compare bone healing induced by equine demineralized bone matrix (DBM) to autogenous cancellous bone graft (ACB) or no graft (control) in a rib-defect model in horses. Methods: The osteogenic properties of ACB and DBM were evaluated in bilateral 19-mm circular defects created in the outer cortex of the 6th and 8th ribs of each horse. Methods: Eight mature horses. Methods: Three rib defects in each horse were randomly treated with each of the 3 treatment groups, and the fourth rib defect received a random treatment. Rib sections, including the defects, were harv...
