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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.
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 2. Ultrastructural enamel findings. Ultrastructural examinations of defined 3 equine enamel types termed equine (Eq.) Types 1, 2 and 3 enamel, according to the transverse appearance of their enamel prisms and the amount and appearance of their interprismatic enamel. Eq. Type 1 enamel contained alternating rows of oval shaped prisms and thick interprismatic enamel plates, and was found adjacent to the amelodentinal junction. Eq. Type 2 enamel consisted of circular, 'keyhole' to 'horseshoe' shaped prisms with little or no interprismatic enamel and was located adjacent to the amelocemental junction. Eq. Type 3 enamel was composed o...
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 3. Dentine. Ultrastructural examinations of equine dentine found that dentinal tubules extended from the amelodentinal junction towards the pulp forming primary curvatures. The number of dentinal tubules/unit area and their diameters increased significantly from the amelodentinal junction towards the pulp cavities, particularly in regular secondary dentine, but irregular secondary (tertiary) dentine contained no dentinal tubules. Dentinal tubules contained odontoblast processes that appeared to extend as far as the amelodentinal junction, but due to iatrogenic loss during specimen preparation, odontoblast...
Power flow in the equine forelimb. A method is described for the estimation of segmental powers and power flow during the stance phase in the equine forelimb, to demonstrate the sources and paths of energy flow through the limb segments. S-VHS video and force platform data were collected for 5 walking trials in a sound Dutch Warmblood horse. Two camera views were combined using direct linear transformation and the resultant sagittal plane positional and angular data used together with the vertical and cranio-caudal ground reaction forces to calculate moments about the ends of the 4 lowermost segments of the forelimb, and the re...
Equine herpesvirus 4 DNA in trigeminal ganglia of naturally infected horses detected by direct in situ PCR. Neuronal and lymphoid tissues of 15 randomly selected horses were analysed post mortem by liquid nested-PCR to study the tropism of equine herpesvirus 4 (EHV-4). In four animals the trigeminal ganglia and in one case the lung were positive. Using a direct in situ PCR the EHV-4 genome was localized in the nuclei of neurons and in the bronchiolar as well as alveolar epithelium of the lung. In none of these tissues could infectious virus or viral antigens be detected. Applying the more sensitive liquid RT-PCR, however, an acute infection was demonstrated in one of the trigeminal ganglia by amplif...
Radiological assessment of the effects of a full rolling motion shoe during asymmetrical bearing. The authors used a new radiological method to assess asymmetrical articular compression of the interphalangeal joints. This method was based on the measurements of 3 angles obtained on dorsopalmar radiographs. Variations of these angles were studied during experimental asymmetrical bearing on unshod feet. It was concluded that 2 angles were interesting parameters to assess asymmetrical articular compression and to define the position of the phalanx in the horny box. Furthermore, variations of these angles induced by experimental asymmetrical bearing were compared without shoe, with a standard ...
Distribution and functional effects of neuropeptide Y on equine ureteral smooth muscle and resistance arteries. The distribution of neuropeptide Y (NPY)-immunoreactive (IR) nerves, as well as the functional effects of NPY and the Y1- and Y2-receptor agonists, [Leu31,Pro34]NPY and NPY(13-36), respectively, have been investigated in vitro in both visceral and arterial smooth muscle of the horse intravesical ureter. NPY-IR nerve fibres were widely distributed along the entire length of the ureter, although the intravesical part was the most richly innervated region, and the only one where NPY-IR ganglion cells were found. NPY (10(-7) M) did not affect either basal tone or spontaneous rhythmic contractions ...
Lateral approach for endoscopic removal of solitary osteochondromas from the distal radial metaphysis in three horses. A lateral approach to the carpal sheath was used for endoscopic removal of osteochondromas from the distal aspect of the radius in 3 horses. Previously osteochondromas have been removed through an incision into the carpal sheath; however, endoscopy is less invasive, requires less surgery and convalescence time, provides better cosmetic results, is associated with a lower risk of infection, and allows better examination of structures within the sheath. A medial approach for endoscopic removal has been described previously; however, the lateral approach was advantageous, because it avoided the m...
[Anatomy of the fetlock joint in horses by means of joint casts]. The equine fetlock joint cavity shows ten pouches. The dorsal recess, which is oriented to the proximal side, is separated from those three pouches, which show to the distal direction, by several capsular folds. These folds are documented by means of sagittal sections through the fetlock joint. A medial/lateral recess is covered by the deep part of the collateral ligament of the fetlock joint. The collateral ligaments as well as the sesamoidean collateral ligaments are closely connected with the joint capsule, from which two capsular folds are separated. Between the part of the sesamoidean col...
The distribution of material properties in the equine third metacarpal bone serves to enhance sagittal bending. The distribution of material properties within the equine third metacarpal bone (MC3), and its possible effect on the mechanics of the structure, was quantitatively evaluated using single-load-to-failure compressive materials testing of specimens from ten horses. Bone samples from six regions within five proximodistal levels of MC3 were milled into right cylinders and compressed at a strain rate of 0.01 s-1. Diaphyseal MC3 bone material was stiffer, stronger, deformed less to yield and failure, and absorbed more energy to yield, than metaphyseal cortical bone material. Lateral and medial MC3 c...
Localization of regulatory peptides in the male urogenital apparatus of domestic equidae: a comparative immunohistochemical study in Equus caballus and Equus asinus. An immunohistochemical study was carried out on specimens of testis, excurrent duct including the male accessory glands and urethra in its various tracts in the horse and the donkey, in order to localize nine regulatory peptides. Immunoreactivities were tested by means of Labelled Strept Avidin-Biotin (LSAB) method. The study has shown that Equine male genitalia are supplied by many peptide immunoreactive nerves containing NPY-, VIP-, leu- and met-Enkephalin-, Substance P-, CGRP- and Bombesin/GRP-like peptides, each of them having a characteristic distribution pattern. These neurotransmitters ...
Effect of maturation and aging on the histomorphometric and biochemical characteristics of equine superficial digital flexor tendon. To assess tendon morphology and non-reducible crosslink concentration, and associations of these findings with horse age and previously reported mechanical and ultrasonographic findings. Methods: Superficial digital flexor tendon samples were obtained from 23 horses aged 2 to 23 years. The tendons had undergone ultrasonography and were submitted to biomechanical testing in the physiologic range prior to sample acquisition. Methods: Samples were sectioned in a transverse plane; then dorsal, palmar, central, lateral, and medial regions were evaluated for fascicle cross-sectional area (CSA), sept...
Ultrasonographic examination of the proximal scutum in the horse. Normal and abnormal ultrasonographic images are presented of the proximal scutum (proximal sesamoid bones and palmar ligament) in the horse. Comparison between anatomical sections, MRI (magnetic resonance imaging) and ultrasound scans enabled the authors to establish the normal ultrasonographic anatomy of the palmar fetlock. Nine cases of proximal scutum injuries were identified ultrasonographically, of which 4 are illustrated. On normal limbs, the facies flexoria of the proximal sesamoid bones appeared as a thin and regular hyperechoic line and the palmar ligament was regularly echogenic. Les...
Sensory epithelium of the vomeronasal organ express TrkA-like and epidermal growth factor receptor in adulthood. An immunohistochemical study in the horse. The medial wall of the vomeronasal organ (VNO) is lined with a sensory epithelium that is closely related to the olfactory epithelium, which is developed from the olfactory placode. It undergoes continuous replacement during its life span. In other sensory epithelia, cell proliferation is under the control of some trophic factors. Whether these proteins are involved in the continuous turnover of the VNO epithelium is unknown. This study approaches this topic by analyzing the occurrence of signal-transducing receptor proteins for neurotrophins (Trk proteins) and epidermal growth factor (EGFr). ...
An in vitro biomechanical investigation of the mechanical properties of dynamic compression plated osteotomized adult equine tibiae. To determine the monotonic mechanical properties of osteotomized adult equine tibiae stabilized with two dynamic compression plates (DCP) and to compare the mechanical properties with those of intact tibiae and in vivo loads. Methods: The compressive, bending, and torsional mechanical properties of plated and intact tibiae were assessed in vitro. Methods: Twelve pairs of adult equine tibiae. Methods: Tibiae were loaded in axial compression, craniocaudal 3-point bending, or torsion in external rotation in a single cycle to failure. Mechanical properties were determined from load-displacement da...
[Observations of the development of the equine distal interphalangeal joint cavity concerning the pelvic limb of fetuses, fillies and adult horses]. Ten horses, younger than 1 year, were used to investigate the articulatio interphalangea distalis of the pelvic limb. The expansion of the dorsal recess was compared to those of adult horses. The recessus dorsalis always formed a shape like the letter 'm' or like a triangle with oblique angles. Consequently the great proximo-distal expansion on the medial side of the dorsal recess very probably has nothing to do with the age of horses.
Effect of bilateral tenectomy of the tensor veli palatini muscle on soft palate function in horses. To determine the effect of bilateral tenectomy of the tensor veli palatini muscle on soft palate and nasopharyngeal function in exercising horses. Methods: 5 Standardbreds. Methods: Treadmill videoendoscopy was performed on 5 Standardbreds exercising at 50, 75, and 100% of the speed that produced maximum heart rate; tracheal and pharyngeal pressures were measured before and after surgery. Tenectomy of the tensor veli palatini muscle was performed bilaterally on each horse while under general anesthesia, using a transoral approach. Results: Peak inspiratory tracheal pressures were significantly...
Magnetic resonance imaging of the brain of normal neonatal foals. Magnetic resonance imaging (MRI) was performed on the brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Intravenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic structures ...
Anatomy of the distal interphalangeal joint of the mature horse: relationships with navicular suspensory ligaments, sensory nerves and neurovascular bundle. The anatomy of the distal interphalangeal (DIP) joint in the adult horse is described in relationship to the suspensory ligaments of the navicular bone, the neurovascular bundle and the sensory nerves to these periarticular regions. Using polymer plastic injections, the synovial cavity of the DIP joint was observed to have a complex relationship to the proximal suspensory or collateral sesamoidean ligament (CSL) of the navicular bone with the cavity forming cranial and caudal compartments around the CSL abaxially. Sensory nerves, as identified by peptide immunocytochemistry and silver/gold chl...
[How to manage a rectal lesion in horses in clinical practice]. The most feared complication after a rectal examination of horses and ponies is to cause a tear of all the layers in the intraperitoneal part of the rectum. The description of the anatomy is an attempt to explain that the rectal tear is mostly located in the dorsal or dorsolateral part of the rectum. This article describes a relatively simple suture technique for the rectal tear by using the needle of Deschamp which is modified by Professor B. Huskamp. Furthermore there is a description of this method as treatment of two horses in practice circumstances. The issue whether causing a rectal tear...
Artifactual nonlinearity due to wear grooves and friction in four-point bending experiments of cortical bone. Experiments and analyses were performed to determine the cause of a nonlinear force-deflection response observed in four-point flexural fatigue of beams of cortical bone machined from the mid-diaphysis of the equine third metacarpus. Observable grooves which formed on the beam surface at supports and load noses were found to be the primary cause of the nonlinearity. An additional geometric nonlinearity at large deflections revealed by finite element modeling may be minimized by using the smallest diameter supports and load noses recommended in ASTM 790. However, frictional constraint of the be...
Intra-abdominal testicular torsion in a horse without signs of colic. A 5-year-old Quarter Horse stallion was admitted for cryptorchidectomy. Abnormalities were not found on physical examination, except for an undescended left testis. Cryptorchidectomy was performed, using an inguinal approach. The tail of the epididymis was in the inguinal canal, and the testis was adjacent to the internal inguinal ring. The testis was dark reddish purple to black, resulting from torsion at the level of the body of the epididymis. On histologic examination, the left testis was necrotic, except for the tunica albuginea and tunica vaginalis visceralis covering the testis. Intra-a...
Pregnancy-associated changes in material properties of the third metacarpal cortical bone in mares. To investigate the effect of late gestation, age, and parity on material properties of third metacarpal (MCIII) cortical bone in mares. Methods: 8 healthy mares (treatment group) that died or were euthanatized within 24 hours after parturition because of foaling complications and 6 age-matched, healthy, nonpregnant mares (control group). Methods: After random assignment for mechanical testing and microradiography, the dorsal half of transverse mid-diaphyseal sections of each MCIII bone was divided into lateral, dorsal, and medial regions. Cylinders of bone from each of the 3 regions were teste...
Residual strength of equine bone is not reduced by intense fatigue loading: implications for stress fracture. Fatigue or stress fractures are an important clinical problem in humans as well as racehorses. An important question in this context is, when a bone experiences fatigue damage during extreme use, how much is it weakened compared to its original state? Since there are very limited data on this question and stress fractures are common in racehorses, we sought to determine the effect of fatigue loading on the monotonic strength of equine cortical bone. Beams were machined from the dorsal, medial and lateral cortices of the third metacarpal bones of six thoroughbred racehorses. Beams from left and...
Ultrasonographic evaluation of the equine placenta by transrectal and transabdominal approach in the normal pregnant mare. The objective of this study was to determine normal variations in the utero placental thickness during mid- and late gestation in the mare. Normal, healthy pregnant mares (n = 9) were examined monthly from 4 mo of gestation until parturition by transrectal and transabdominal ultrasonography. At each examination, the combined thickness of the uterus and the placenta (CTUP) was measured at the placento-cervical junction (transrectally) and at the uterine body or the uterine horns (transabdominally). In addition, the echogenicity of the amniotic and allantoic fluids was evaluated by transrectal u...
1H-NMR study of inter-segmental hydrogen bonds in sperm whale and horse apomyoglobins. NMR signals for HisB5 N(delta)H and HisEF5 N(epsilon)H protons of sperm whale and horse apomyoglobins were assigned and compared with the corresponding signals of the holoproteins in terms of pH and temperature dependence behaviors of their shifts and line widths in order to gain insight into structural difference between the apoproteins and the holoproteins. Since these protons are involved in internal hydrogen bonds at the interfaces between the B helix and the GH corner and between the EF corner and the H helix, local structures of the interfaces in these proteins have been inferred from th...
