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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.
Regional blood flow to the stomach and small intestine in ponies. Studies on regional blood flow to the stomach and small intestine were performed in 9 anesthetized ponies. Carbonized microspheres (15 +/- 5 micron in diameter) labeled with 85Sr were injected into the left atrium to determine blood flow distribution. In 4 ponies, the regional flows to mucosal-submucosal layers of the stomach and the small intestine were also measured. The nonglandular region of the stomach received the least blood per 100 g of tissue, and the duodenum received the greatest. The regional blood flow to the duodenum was significantly higher than that to the glandular stomach reg...
Vestibular disease, and its relationship to facial paralysis in the horse: a clinical study of 7 cases. The signs observed in 6 cases of peripheral vestibular disease included incoordination, head tilt and nystagmus. The intensity of the signs varied greatly with duration of the disease, and in 3 cases facial paralysis was also present. Tympanosclerosis was demonstrable in all cases subject to radiology. Trauma was the causative factor in most cases. The causes of, and relationships between, vestibular dysfunction and concomitant facial paralysis are discussed. The exact etiology of the tympanosclerosis is unknown.
Ultrastructural observations suggesting merocrine secretion in the initial segment of the mammalian epididymis. Principal cells in the initial segment of the epididymis in horses, cattle, pigs, sheep, dogs, cats, and rabbits have an abundant, partly rough, endoplasmic reticulum and a large Golgi complex. Small vacuoles with opaque content seem to be formed by the Golgi complex and move to the cell apex, where they empty their contents into the lumen by a merocrine mechanism.
Vasculature of the equine and canine iris. Methyl methacrylic casts were prepared and tissue was freshly collected for histologic examination to compare the vascular supply and the structure of the vessels of the iris in the adult horse with those of the dog. In the horse, ciliary blood vessels divided in the iris and formed a complete major arterial circle of the iris. In the dog, the ciliary blood vessels divided in the ciliary body and, by means of recurrent branches, formed a complete arterial circle. From this circle, radial arteries extended toward the pupillary margin. The radial vessels in the horse were nearly straight and joi...
Studies on the equine placenta. III. Ultrastructure of the uterine glands and the overlying trophoblast. Ultrastructural studies of the uterine glands at intervals during pregnancy in the mare show that secretory activity continues after formation of the placental exchange units. The nature of the glandular secretion appeared initially to be proteinaceous, but cellular debris was also present during the last third of gestation. These secretions were absorbed by the trophoblast overlying the mouths of the glands. The fate secretions and their significance for the fetus and placenta are unknown.
[The arterial vessels and their intraosseous course in the leg bones of foals. II. Humerus]. The arterial blood vessels in 24 humeri of equine fetusses and foals are described. The relation between the age and the distribution of these arteries are explained and completely discussed.
Syringomyelia in a thoroughbred foal. The report describes a case of myelodysplasia involing spinal cord segments C7 to T8 of a 5 month old part-Thoroughbred foal. There was a single extensive syringomyelic and hydromyelic cavity which extended from the seventh cervical segment (C7), to the seventh thoracic segment (T7), abnormal size and shape of central canal, and disorderly differentiation of the grey and white matter. The cause of the defect is unknown.
A correlation of the endoscopic and pathological changes in subclinical pathology of the horse’s larynx. The larynges of 6 horses were examined endoscopically and the findings correlated with the gross and histological appearance of the intrinsic laryngeal muscles and their nerve supply. In all cases it appeared that the balance between abductor and adductor muscle groups had been lost due to preferential atrophy of individual muscles or groups of muscles. The laryngeal abnormalities recorded were asymmetry of the larynx with asynchronous left sided abduction and fluttering or trembling of the left vocal cord and arytenoid cartilage. It is suggested that these changes represent the early signs of...
Radiological protection in equine radiography and radiotherapy. The principles of radiological protection are summarised and consideration is then given to problems, which may confront the equine practitioner, in the fulfillment of these principles during diagnostic radiography of the limbs, head, and spine of the horse. The place of anaesthesia in such procedures is discussed and the special problems associated with therapeutic radiography of the horse are considered.
Telemetric measurements of strain in the metacarpus of the horse: a pilot study. The advances made by the use of a telemetric system in the study of bone strain in a free-moving horse are reported. A rosette strain gauge was bonded to the craniomedial aspect of the metacarpus of the horse. Attachment of a miniature FM transmitter to lead wires facilitated telemetric transmission of of resistance changes which corresponded to limb movement. During 3 different gaits, the trace pattern remained similar, although frequency and amplitude varied. The tracings were similar to those reported in other species in which nontelemetric transmission was used.
Intramural esophageal cyst in a horse. A yearling Quarter Horse colt was examined because of intermittent esophageal obstruction. A soft tissue mass was palpated in the cervical portion of the esophagus. Plain and contrast radiography and esophagoscopy were utilized to confirm the location of the lesion in the esophageal wall. Surgical exploration and removal of the mass was performed through a ventral midline cervical incision. Histologically, the mass was a keratinizing squamous epithelial inclusion cyst.
Horner’s syndrome in large animals. The sympathetic nervous innervation of the head was surgically transected in the horse, cow, sheep and goat. The site of transection was preganglionic in all 4 species and ganglionic-postganglionic in 2 additional horses. The Horner's syndrome, manifested as a result of the iatrogenic lesion, varied with the species. Ptosis was the most constant sign in all species. Unilateral sweating over the face and proximal neck, particularly at the base of the ear, was the most prominent feature in the horse. The cow revealed distension of vasculature and cutaneous heat of the pinna, and a reduced produc...
Ischemic myelopathy caused by fibrocartilaginous emboli in a horse. A horse that suddenly became recumbent had a focal ischemic infarct of the spinal cord between C6 and C7. The infarct was attributed to multiple fibrocartilaginous emboli. Adherence of fibrocartilaginous debris to the outer surface of the dura was interpreted as evidence that intervertebral disc degeneration and displacement of the nucleus pulposus had occurred and that the emboli arose from the disc.
Surgical approach to the equine brachial plexus. Eleven ponies were used to perfect a surgical approach to the brachial plexus that would offer maximal exposure to the plexus, with minimal trauma. One pony was euthanatized to determine whether surgical exposure to the plexus was feasible. By approaching the plexus from the prescapular region, the only muscle that was found necessary to incise was the cutaneus omobrachialis. The rest of the procedure required only blunt dissection. In the other 10 ponies, the wounds healed by first intention, and the gait was not affected by the surgery.
Coronary arterial anatomy of the small pony. Ventricular weights and coronary arterial distribution and diameters were determined in 10 small adult ponies (139 +/- 32 kg). Combined ventricular weights averaged 0.52% of the body weight, with an average of 77% of the total ventricular weight being the left ventricle. The pony is right coronary predominant, with the interventricular subsinusoidal branch of the right coronary artery and interventricular paraconal branch of the left coronary artery providing comparable blood supply to the left ventricular free wall and septum.
Some problems associated with intestinal surgery in the horse. The paper considers the general principles of intestinal surgery in the horse and illustrates a theatre layout suitable for this purpose. The problems of locating and reducing obstructions of the small and large intestine are discussed, with particular emphasis on incarcerations of the small bowel and the techniques of jejunal and ileal re-implantation after bowel resection.
The arterial supply of the navicular bone and its variations in navicular disease. Macroscopic, microscopic and radiological examinations of the navicular bones of 83 horses and ponies showed that the navicular bone in the adult horse has 2 principal routes of blood supply. One supply is present at birth, the other develops within the first 2 to 3 years of life, in response to increasing activity. The size of the nutrient foramina, as seen on radiographs, is related to the type, frequency and regularity of work done by the horse. These foramina are normally conical in shape, alteration to a circular, or mushroom-shape being evidence of occlusive vascular disease in the navic...
