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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.
Arthroscopic approach and intra-articular anatomy of the plantar pouch of the equine tarsocrural joint. Arthroscopic examination of structures within the plantar pouch of the tarsocrural joint was accomplished via portals in both the plantaromedial and plantarolateral aspects of the joint. Flexion and extension of the tarsus while examining the joint through either portal allowed observation of the proximal and plantar aspects of the lateral and medial trochlear ridges, the trochlear groove, the caudal aspect of the distal tibia, and the deep digital flexor tendon (DDFT) in its sheath. From a plantarolateral portal, the plantar talocalcaneal ligament and the plantar aspect of the lateral malleol...
Lipid analysis of lavage samples from the equine guttural pouch (auditory tube diverticulum). The guttural pouch is a large, air-filled diverticulum of the auditory tube, present in the horse and other species. Lipid analysis of saline lavage from the equine guttural pouch has demonstrated the presence of phospholipids and neutral lipids in amounts that are variable but consistently greater than in any other species described. A stain specific for choline-containing phospholipids has demonstrated the presence of phospholipid-containing vesicles only within the cells of subepithelial, seromucoidlike glands, suggesting that these cells incorporate phospholipids in their secretions. The f...
Histochemical and functional evidence for a cholinergic innervation of the equine ureter. The distribution of acetylcholinesterase (AChE)-positive nerve fibers and cells, as well as the effects of acetylcholine (ACh) on ureteral smooth muscle and small resistance arteries were investigated in the equine ureter by means of histochemical, classic organ baths and myograph techniques. AChE-positive nerve fibers were widely distributed throughout the ureteral wall forming muscular, subepithelial and perivascular nerve plexuses, whose density was highest at the intravesical ureter. AChE-positive nerve cells were also identified grouped as adventitial or intramural ganglia. ACh increased ...
The relationship between intra-articular and juxta-articular intraosseous pressures in the metatarsophalangeal region of the pony. Eight metatarsophalangeal (fetlock) joints were studied in anaesthetized young ponies. Pressure measurements were made in the joint and at various sites in the marrow cavity of the third metatarsal bone with simultaneous measurement of systemic arterial and venous blood pressures. Fetlock joint flexion was always associated with a statistically significant initial decrease in intra-articular pressure (p < 0.05) followed by a marked increase in pressure (p < 0.05). Subsequent extension was accompanied by a similar pressure pattern, although there appeared to be a hysteretic relationship. ...
Renal dysplasia and benign ureteropelvic polyps associated with hydronephrosis in a foal. A 4-month-old male Trakehner foal with a history of hematuria, poor growth, and abnormal hair was found to have unilateral hydronephrosis and hydroureter, as determined by ultrasonography and surgical exploration. Nephrectomy and ureterectomy were performed as treatment. Gross examination of the ureter and kidney revealed renal pelvic and ureteral polyps causing obstruction and subsequent hydronephrosis. The histologic features were consistent with renal dysplasia. The polyps and renal dysplasia were likely to be congenital, but the etiopathogenesis is not known. The finding that urinary outfl...
Mucinous hyperplasia in the kidney and ureter of a horse. A case of mucinous hyperplasia in the right renal pelvis and ureter is reported in a 23-year-old, male, Quarter horse. The affected right renal pelvis was markedly distended and filled with inspissated yellowish-green mucous material compressing the adjacent cortical and medullary parenchyma. Multiple, similar masses were present protruding from the right urethral mucosa. Histologically, the masses were characterized by a cystic glandular and papillary hyperplasia of the mucosa of the renal pelvis and ureter. This is believed to be the first reported case in an equine species.
[Case report of a complex odontoma in a horse–clinical picture, radiography, ultrasonography and computed tomography]. The clinical signs, diagnosis and pathology of an adult horse with a complex odontoma are described. Computer tomography was shown to be a new diagnostic technique with outstanding potential in the investigation of diseases of the equine head.
Relationships between radiography of cervical vertebrae and histopathology of the cervical cord in wobbling 19 foals. Nineteen wobbling foals (17 males and 2 females) showing lameness of hindlimbs at 6 to 21 months of age were investigated radiographically and histopathologically. Minimum sagittal diameter (MSD), minimum flexion diameter (MFD) and minimum dural sagittal diameter (MDD) were measured on plain radiograms or myelograms taken at neutral and flexed positions as indicators of narrowed vertebral canal. After necropsy, the cervical spines and the spinal cord were examined macroscopically and respectively the relationships between radiographic findings and the corresponding morphological lesions were e...
Right hepatic lobe atrophy in horses: 17 cases (1983-1993). The case records of 17 horses with atrophy of the right hepatic lobe were reviewed. Fifteen horses had signs of colic. Two horses had clinical problems that were unassociated with gastrointestinal tract disease. Ages ranged from 5 to 30 years (mean, 12.6 years) and there was no breed or sex predisposition. In clinically normal horses, the right hepatic lobe constitutes half of the total liver weight. The right hepatic lobe in the 17 horses in this study ranged from 11.0 to 38.3% of the total liver weight (mean, 27.8%). Findings on histologic examination of hepatic tissue from horses in the stu...
An ultrastructural study of intranuclear bodies in granular epithelial cells of the equine small intestine. Gastrointestinal disorders and colic are common problems of
horses. In spite of its clinical importance, only a few reports
deal with the normal morphology of the equine intestinal barrier
(Roberts and Hill 1974). Furthermore, the intestinal epithelium
of horses presents some characteristics which are uncommon in
other species, e.g. the presence of conspicuous Paneth cells
(Meyer et al. 1970) or granular epithelial cells. Paneth cells
occur in the small intestinal crypts and sporadically in the caecum, while granular cells occur along the lining of the small
and large intestine in hors...
Structure of equine type I and type II collagens. Collagen type I was purified from equine skin and flexor tendon, and type II collagen was purified from equine articular cartilage. The proteoglycans in these tissues were extracted, using guanidine HCl; the collagens were solubilized, using pepsin digestion, then were selectively precipitated with NaCl. Gel electrophoresis indicated that the precipitates contained only type I or type II collagen. Amino acid analysis indicated that collagen constituted > 97% of the total protein in the precipitates. Hydroxylation of proline was 42.0 +/- 0.6% (mean +/- SEM) in alpha 1(I) and alpha 2(I), and was...
Morphological, histochemical, and myosin isoform analysis of the diaphragm of adult horses, Equus caballus. The horse provides an interesting model for study of the structure and function of the mammalian diaphragm. Multiple regions of diaphragm from seven adult horses were prepared for histochemistry, immunocytochemistry, myosin heavy chain electrophoresis, and native myosin electrophoresis. Two additional adults were dissected to demonstrate myofiber and central tendon morphology and stained for acetylcholinesterase to demonstrate motor endplates. All regions of the adult diaphragm were histochemically characterized by a preponderance of type I fibers with some type IIa fibers. Type IIb fibers wer...
Jugular vein wall repair after intravenous injection in equids. The evolution of the healing process of venous puncture wounds was studied macroscopically and light-microscopically in order to determine the time of venipuncture. Seven small equids of various ages, all in normal healthy condition, were experimentally injected in the external jugular vein with a physiological Hartmann solution at different times before euthanasia. Two types of needle diameters i.e. 16.5 G and 19 G, were used. A fairly good uniformity in the healing process was seen in the 7 animals. In most cases the lesions induced within 5 weeks before death were macroscopically visible, w...
Pulmonary intravascular macrophages in horses and ponies. Seven horses (4 anesthetized and 3 awake) and 2 ponies (anesthetized) were studied to evaluate the high sensitivity of the pulmonary circulation of the horse to various blood-borne particles, and to establish the presence of intravascular macrophages in the lung. Pulmonary and systemic pressures and cardiac output before and during particle injection were measured in some animals. An anesthetized foal had a large increase in pulmonary arterial pressure (32 and 34 mm of Hg) within 1 minute of IV administration of small test doses of radioactively labeled liposomes (2.5 mumol/kg of body weight) ...
Jean-François Bouley (Bouley jeune). Pioneer investigator in intermittent claudication. Reports of pathologic investigations as to the cause of intermittent claudication in horses were made in France in October, 1831, by veterinarian Jean-François Bouley. Obstructive clots in the femoral arteries were found to be responsible for the muscular changes causing limping. Bouley's work in the horse was used by Charcot in 1858 to understand the mechanism of claudication in the case of a soldier with gunshot wound in whom a traumatic aneurysm, clotting, and ischemia of the legs developed. This was not, however, the first medically reported case of human claudication from vascular occlus...
Preparation and characterization of monoclonal antibodies against equine chondrocytes, osteoblasts and osteocytes. Three monoclonal antibodies capable of individually recognizing chondrocytes, osteoblasts and osteocytes were prepared. EB-1 reacted with a 55-kDa antigen on the chondrocyte membrane, EB-2 with a 110-kDa antigen on the membrane of osteoblasts and/or partial osteocytes, and EB-3 with a 130-kDa antigen on the membrane of osteocytes. These monoclonal antibodies may be useful probes for studying the differentiation and maturation of osteogenic cells.
Enterolithiasis in two zebras. Enterolithiasis, as a cause of colic, was diagnosed and treated during surgical intervention in 2 Grant's zebras (Equus burchelli bohmi). The zebras were part of a wild herd in a zoo in the western United States. The clinical signs of enterolithiasis in both zebras were similar to those reported for horses. Analysis of the enterolith from 1 zebra revealed a composition identical to enteroliths that have been analyzed from horses. Three other zebras from this herd had enteroliths at necropsy. Enterolithiasis should be considered as a differential diagnosis for zebras with low-grade obstructive ...
Effect of oxytetracycline on metacarpophalangeal and distal interphalangeal joint angles in newborn foals. Thirty-five newborn foals were assigned to 1 of 3 groups and treated with 0.9% NaCl solution (saline; group 1; n = 12), oxytetracycline (44 mg/kg of body weight; group 2; n = 12), or 2-pyrrolidone (oxytetracycline vehicle; group 3; n = 11) in saline solution during the first 36 hours after birth. Serum biochemical analyses were performed on samples obtained from group-1 and group-2 foals before treatment and 24 and 96 hours after treatment. Lateral to medial radiographic views of the forelimbs were obtained before treatment and 24 and 96 hours after treatment in all foals. Metacarpophalangeal ...
Natural outcome and ultrasonic identification of equine fetal twins. The natural outcome of bilateral twins (one in each uterine horn) that were viable on Day 40 was studied in 15 pony mares. Fetuses were monitored by transrectal ultrasonography until the outcome was determinable. One fetus (2 mares) or both fetuses (8 mares) died (cessation of heartbeats) during Months 2 and 3. Loss of fetuses was externally observed in 4 additional mares during the late fetal stage (Months 8 to 11); 2 mares lost 1 fetus and 2 lost both fetuses. Birth of 2 live foals occurred in only 1 of 15 mares (7%) First day of detected apposition between portions of the 2 allantochorions ...
Ameloblastomas in the horse: a critical review and report of an additional example. Previously published cases of ameloblastoma in the horse are reviewed in detail for their acceptability as examples of that tumor; an additional one is described. So far, this rare equine lesion has been shown to have two histologic patterns. The first consists of islands and sheets of epithelium that exhibit the basal cell characteristics of ameloblastoma; the central cells comprise stellate reticulum. The second exhibits these basal cell features less markedly and the central cells are spindle-shaped and closely packed. The biologic behavior of the equine ameloblastoma is thought to be the s...
[Pathology of cardiac ventricular aneurysms in the horse]. The authors describe pathologic and histopathologic findings of three cardiac aneurysms in horses, two of which in the left ventricle and one in the right ventricle. The aneurysms were always associated with multiple foci of myocardiac fibrosis. A hypothesis concerning histogenesis of the lesion is formulated.
Measurements of urethral pressure profiles in the male horse. Urinary tract pressure profiles were evaluated in 6 clinically normal geldings over 3 consecutive days. This was performed by introducing a 1.3 m-long cuffed catheter into the urinary tract, under xylazine sedation (0.8 mg/kg, iv). The method was reproducible. The mean (+/- sd) intra-vesicular pressure (IVP) and maximal urethral closure pressures (MUCP) were 10.3 (+/- 1.7) and 129.8 (+/- 19.6) cmH2O, respectively, and the ratio between MUCP and IVP was 13.2 (+/- 2.5). A gelding with urinary incontinence showed a significantly lower MUCP (73.4 cmH2O), and an MUCP to IVP ratio of 8.0. It was con...
Cystic adenomatous hyperplasia of the equine allantois: a report of eight cases. No abstract available
[The discovery of a horse skeleton from the 17th century in Kiesen in Bern canton]. In 1968 a skeleton of a horse was found in Kiesen (Switzerland). This discovery could be dated by radiocarbon method: According to that this 13 years old gelding with a withers-height of 135 to 140 cm must have lived during the first third of the 17th century. Apparently it died by an accident. The bones are fully documented with pictures and scales and the findings described and discussed in detail.
Solitary osteochondroma of the nasal bone in a horse. A 3-year-old Appaloosa stallion with a 4 cm x 4 cm x 2.5 cm mass protruding from his nasal bone was evaluated. Radiographs revealed an osseous mass, with a radiopaque outer margin and several radiolucent areas within the body of the mass. The mass was surgically removed and evaluated histopathologically. The histopathological diagnosis was osteochondroma. This case represent the first reported occurrence of an osteochondroma arising from intramembraneous bone in the horse.
[Ultrasonography of ovarian pathology in the mare: a review for the practitioner]. The aim of this review is to give the practitioner the ability to be familiar with the echographic exam of ovarian abnormalities. He should be able to recognize different stages of the development of these important structures and to estimate the effect that they can have on the normal cycle of the mare. Various specific criteria and details regarding the equine echography of ovarian abnormalities are reported and illustrated, using the last scientific data published on that particular topic.
