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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.
The site of focal osteomyelitis lesions in foals. The long bone ends of foals with infectious disease were sawn into sagittal slabs, washed and inspected. Tissue suspected to be abnormal on the basis of change of colour and consistency was radiographed, and then decalcified and examined histologically. The exact site of 140 focal osteomyelitis lesions from 18 foals was determined. There were more lesions in the epiphysis than the metaphysis. Epiphyseal lesions were in specific sites within a given epiphysis, and in most epiphyses the lesions were at the site of thickest cartilage. Metaphyseal lesions in the metacarpal, metatarsal and distal r...
Epidermal cell renewal in the horse. Epidermal cell labeling index and cell renewal time were estimated in 8 adult horses, using autoradiography after [3H]thymidine was given intradermally. The mean labeling index was 1.45 +/- 0.47%, and the mean cell renewal time of the viable epidermis was approximately 17 days.
Incomplete palmar fracture of the proximal extremity of the third metacarpal bone in horses: ten cases (1981-1986). In 4 adult horses, simple, nondisplaced, incomplete fracture of the proximal extremity of the third metacarpal bone (MC3) was identified radiographically only on the dorsopalmar projection. Lameness was slight to moderate. Although nerve blocks of the foot and fetlock did not alter the lameness, high palmar regional nerve block improved the gait in 1 of the 2 horses on which it was performed. Pain on palpation or swollen distal accessory (inferior check) ligament, flexor tendons, and suspensory ligament were not found in any horse. The fracture was localized to the palmar surface of the proxim...
Effects of age, sex, and post mortem interval on intestinal lengths of horses during development. Lengths of small intestine, caecum, ascending colon and descending colon were measured in intestinal tracts from 103 foetuses, foals and adult horses. Intestinal tracts from 21 of the horses were measured at varying intervals after death. Total intestinal length increased markedly from mid-gestation to one year of age, then showed little increment up to 35 years. Small intestinal length increased most rapidly in the first month of life. Caecal length increased most rapidly from one to six months and length of ascending colon increased most rapidly between one week and one year. Descending colo...
[The diagnostic value of the ‘skyline’ view for the radiographic study of the navicular bone in horses]. The radiographic diagnostic value of Rose's palmaroproximal-dorsodistal ('skyline') projection and Oxspring's dorsopalmar projection of the equine navicular bone were compared, by examining radiographs of 102 navicular bones originating from 66 randomly selected horses with clinical evidence of lameness located in the navicular area. In 27 navicular bones essential information was obtained from the skyline view, 15 independently of Oxspring's projection and 12 in addition to this view. For 11 navicular studies the D.P. projection was the most important diagnostic view. In the other 64 navicula...
Ciliated protozoa in the colonic wall of horses. Ciliated protozoa of several morphological types were found in the colonic tissue of 8 horses, mostly immature Standardbreds. Most of the protozoa observed appeared similar to those normally found as commensals in the equine large intestinal lumen. In all cases, organisms were located in the lamina propria; organisms were also found in the submucosa of 2 horses. The association of colonic disease with the presence of intramural ciliates was unclear.
Scintigraphic appearance of stress-induced trauma of the dorsal cortex of the third metacarpal bone in racing Thoroughbred horses: 121 cases (1978-1986). Review of 121 bone scintigrams obtained on racing Thoroughbred horses with clinical histories indicative of forelimb lameness revealed 3 scintigraphic patterns of stress-induced trauma to the dorsal cortex of the third metacarpal bone: (1) focal, intense uptake associated with recent stress fracture; (2) regional uptake of varying intensity or a mixed pattern of uptake associated with chronic stress fracture; and (3) diffuse, mild to moderate uptake associated with periostitis (bucked shins). The latter scintigraphic pattern appeared to be an exaggerated manifestation of the normal remodeling ...
Subchondral cystic lesions (osteochondrosis) of the femoral heads in a horse. Bilateral subchondral cystic lesions of the femoral head in a horse resulted in lameness. The lesions had resulted in degenerative disease in the left coxofemoral joint. The cause of lameness was confirmed by use of intra-articular anesthesia, joint fluid analysis, and radiography. Subchondral cystic lesions involving the femoral head should be considered in the differential diagnosis of equine lameness localized in the upper portion of the hind limb.
Effect of dorsopalmar projection obliquity on radiographic measurement of distal phalangeal rotation angle in horses with laminitis. The effect of dorsopalmar projection obliquity on calculation of distal phalangeal rotation (DPR) angle was determined in 8 feet obtained from 5 horses that had been euthanatized because of laminitis. A true lateromedial view of each foot served as a reference, with additional views taken at 5, 10, 15, and 20 degrees of x-ray tube head rotation in both a dorsal and in a palmar direction. Projection obliquity resulted in consistent underestimation of DPR angle. Where projection obliquity exceeded 10 degrees, there were significant (P less than 0.05) differences in DPR angle. The magnitude of un...
T lymphocyte development in horses. I. Characterization of monoclonal antibodies identifying three stages of T lymphocyte differentiation. Six monoclonal antibodies reacting with equine T lymphocytes at different stages of maturation were selected from antibodies produced against lymphoid cell preparations. EqT12 and EqT13 antibodies identified subsets of cortical thymocytes with high terminal deoxynucleotidyltransferase (TdT) activity and no phytolectin responsiveness. EqT12+ thymocytes were scattered throughout the cortex while EqT13+ thymocytes were located in the subcapsular cortex. EqT12 bound to small numbers of bone marrow cells, splenocytes, and circulating lymphoid cells, but not to mature T lymphocytes. EqT13 bound to v...
Bone lesions caused by Pythium insidiosum in a horse. A 5-year-old, female saddle horse developed a tumoral mass anterolaterally on the metacarpal region of its right front leg. Histopathological study showed hyaline, aseptate, broad hyphae in the sequestered coral-like necrotic masses. Radiographs revealed an extensive osteomyelitis with disorganized bone proliferation of the metacarpal bones, as well as exostosis of the distal radius and the proximal and distal row of carpal bones. The etiologic agent was detected histologically, isolated in culture and identified as Pythium insidiosum. Serological tests were positive. Immunotherapy was applied...
Distribution and ultrastructure of mast cells in the equine respiratory tract. Mast cells in the equine respiratory mucosa were studied at both light--and transmission electron--microscope levels. Mast cells were identified at all levels of the tract, with the greatest cell density in the nasopharynx. The majority (57 to 94 per cent) of this cell population were located within the connective tissue of the lamina propria. Up to 20 per cent of these cells were associated with the mucosal glandular tissue, whilst small numbers were present within the surface epithelium and in association with nodular lymphoid tissue. In the peripheral lung tissue 20 per cent of the mast cel...
Microcirculation of the coronary band of the equine hoof. Scanning-electron-microscopic examination of corrosion casts was used to investigate the microcirculation of the coronary border of the equine hoof. Numerous peg-shaped capillary plexuses derived from arterioles extended distally from the dorsal branches of the digital arteries parallel to the hoof wall. The plexuses varied in length and consisted of a fine network of interconnected capillaries that converged to join a centrally situated venule. These centrally situated venules within the papillary plexuses gave rise to a vast venous plexus deep to the coronary band.
Comparative scanning electron-microscopic study of the lingual papillae in two species of domestic mammals (Equus caballus and Bos taurus). II. Mechanical papillae. The mechanical papillae of the horse and cow were studied by scanning electron microscopy in order to determine their morphostructural characteristics and the differences between the two species. The horse has only thin, small and interlaced filiform papillae, while the cow shows robust and more ordered filiform papillae. Furthermore, the cow tongue presents conical and lenticular papillae surrounded by a papillary groove. A characteristic distribution of stratified scales and channeled tracts is observed in conical and lenticular papillae but not in the filiform papillae. The morphostructural...
Breathing strategy of the adult horse (Equus caballus) at rest. To investigate the mechanism underlying the polyphasic airflow pattern of the equine species, we recorded airflow, tidal volum, rib cage and abdominal motion, and the sequence of activation of the diaphragm, intercostal, and abdominal muscles during quiet breathing in nine adult horses standing at rest. In addition, esophageal, abdominal, and transdiaphragmatic pressures were simultaneously recorded using balloon-tipped catheters. Analysis of tidal flow-volume loops showed that, unlike humans, the horse at rest breathes around, rather than from, the relaxed volume of the respiratory system (Vr...
Classification of the main macroscopic lesions produced by larvae of Gasterophilus spp. (Diptera:Gasterophilidae) in free-ranging horses in Umbria. Listed and described herein are the main macroscopic lesions produced along the whole digestive tract of free-ranging horses by larvae of the five Gasterophilus spp., occurring in Umbria, a region of central Italy: Gasterophilus intestinalis, Gasterophilus nasalis, Gasterophilus pecorum, Gasterophilus inermis, Gasterophilus haemorrhoidalis. Lesions are classified on the basis of their sizes and shapes and the host's anatomic sites infested, and they are examined in relation to the developmental stages of larvae causing them. The examination of the lesions shows that it is very difficult to dif...
Heparan sulfate proteoglycan from human and equine glomeruli and tubules. 1. Proteoglycans were isolated from human and equine glomeruli or tubules by guanidine extraction and anion exchange chromatography. 2. These proteoglycan preparations contained about equal amounts of heparan sulfate and chondroitin sulfates. 3. During the preparation of glomerular or tubular basement membranes the main part of proteoglycans (greater than 50%) was extracted in the salt extract. Chondroitin sulfate proteoglycan was mainly found in the water and salt extracts of glomeruli and tubules, heparan sulfate proteoglycan in the deoxycholate extracts and the basement membranes. 4. The gl...
[The optimal radiologic presentation of the horse digit under practice conditions]. Requirements for optimal radiography of the horsetoe are described. Examples are given for getting X-rays of high quality under practice conditions, by using special intensifying screens and all the possibilities of radiological technique to guarantee a short exposure time.
Purification of brush border membrane vesicles from horse kidney cortex using Percoll. A rapid method for preparation of brush border membrane vesicles from a large amount of horse kidney cortex is described. Self-orienting Percoll-gradient centrifugation minimized contamination by microsomal membranes. The characteristics of this preparation were checked by electron microscopy and measurement of L-alanine uptake.
Morphologic effects of experimental distention of equine small intestine. The morphologic effects of induced intraluminal hydrostatic pressures (IHPs) of 0, 9, and 18 cm H2O were evaluated in 33 isolated equine jejunal segments. Fifteen segments were distended with Tyrode's solution for 1 hour and nine segments for 4 hours. Tyrode's solution was added as needed to maintain the prescribed pressures. Nine other segments were left undisturbed for 4 hours after the initial distention period. On decompression of the intestinal segments, progressive peristaltic contractions resumed in all segments. Evaluation of intestinal sections by light microscopy and transmission ele...
Results of operative treatment of equine colic with special reference to surgery of the ileum. This retrospective study presents the results of surgical treatment of obstructive colic in horses operated in the last decade (1976-1985). The overall short-term recovery rate (i.e. discharged from hospital) was 51% of cases presented for surgery, and 68% of cases which were considered to be amenable to surgical therapy. For long-term results (6 months-8 years follow up) these percentages must be reduced by about 15% due to mortality after discharge. Special attention has been given to surgery of the ileum, which is often involved in strangulation or obturation, and accounts for about 26% of ...
Calibration of the mercury-in-silastic strain gauge in tendon load experiments. A calibration method is presented by which the signals of mercury-in-silastic strain gauges (MISS), implanted in the tendons of in vitro loaded equine hindlegs, were converted to tendon loads. The relationships between MISS-signals and tendon loads were obtained from tensile-force tests applied to the tendons. Special attention was paid to the correction of the MISS-signals for amplitude-shifts resulting from internal repositioning of the MISS after tendon isolation and temperature differences. Shift corrections equivalent to tendon strains up to 2.8% were necessary in the in vitro experiment....
Histology of the post partum equine uterus as determined by endometrial biopsies. Altogether 156 equine endometrial biopsies were carried out during the post partum (p.p.) period: immediately after parturition until 15 days after foaling. The histological changes are described. The rapid restoration of the equine endometrium is remarkable. The destruction of the luminal epithelium is minor and regeneration takes place rapidly. Remnants of the placenta, the microcotyledons and desquamated cells, have disappeared by 5 p.p. The transformation of glands from a pronounced secretory pattern to normal appearance also takes only 5 days. The occurrence of neutrophils and lymphocytes...
Astrocytes in the guinea pig, horse, and monkey retina: their occurrence coincides with the presence of blood vessels. In the present study the distribution of astrocytes in the nerve fiber layer (NFL) has been studied in the sparsely vascularized retinae of the guinea pig and horse and in the richly vascularized retina of the Old World monkey (Cercopithecus aethiops) using immunocytochemical methods. In the guinea pig retina glial fibrillary acidic protein (GFAP)-positive astrocytes could not be detected. They were found, however, in the myelinated region of the optic nerve. The optic nerve head and a small retinal region immediately adjacent to it contained few vimentin-positive astrocytes. Histological sect...
