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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.
Effect of exercise on age-related changes in collagen fibril diameter distributions in the common digital extensor tendons of young horses. To determine whether specific treadmill exercise regimens would accelerate age-related changes in collagen fibril diameter distributions in the common digital extensor tendon (CDET) of the forelimbs of young Thoroughbreds. Methods: 24 female Thoroughbreds. Methods: Horses were trained for 18 weeks (6 horses; short term) or 18 months (5 horses; long term) on a high-speed treadmill; 2 age-matched control groups (6 horses/group) performed walking exercise only. Horses were (mean +/- SD) 24 +/- 1 months and 39 +/- 1 months old at termination of the short-term and long-term regimens, respectively. ...
Electromyographic activity of the stylopharyngeus muscle in exercising horses. There is a need to understand the process which leads to failure of recruitment of the stylopharyngeus muscle in clinical cases of nasopharygeal collapse. We therefore studied the timing and intensity of stylopharyngeus muscle activity during exercise in horses. Objective: To measure the electromyographic (EMG) activity of the stylopharyngeus muscle in exercising horses and correlate it with the breathing pattern. Methods: Five horses were equipped with a bipolar fine wire electrode placed on the stylopharyngeus muscle and a pharyngeal catheter. The horses exercised on a treadmill at speeds co...
Influence of species and anatomical location on chondrocyte expansion. Bovine articular cartilage is often used to study chondrocytes in vitro. It is difficult to correlate in vitro studies using bovine chondrocytes with in vivo studies using other species such as rabbits and sheep. The aim of this investigation was to study the effect of species, anatomical location and exogenous growth factors on chondrocyte proliferation in vitro. Methods: Equine (EQ), bovine (BO) and ovine (OV) articular chondrocytes from metacarpophalangeal (fetlock (F)), shoulder (S) and knee (K) joints were cultured in tissue culture flasks. Growth factors (rh-FGFb: 10 ng/ml; rh-TGFbeta: 5...
Immunoexpression of androgen receptors in the reproductive tract of the stallion. The objective of this study was to visualize androgen receptors (ARs) in the testis, epididymis, and prostate of the stallion by means of immunohistochemistry. Nuclear immunostaining was found in all somatic cells in the testis--Leydig, Sertoli, and peritubular myoid cells; in both types of epithelial cells of the epididymis; and in the secretory cells of the prostate. These results indicate that ARs are distributed throughout the reproductive tract cells of the stallion.
A new relaxed state in horse methemoglobin characterized by crystallographic studies. A new relaxed state has been characterized in the crystals of horse methemoglobin grown at neutral pH at low ionic concentration and their low humidity variants. The crystals provide an example for improvement in X-ray diffraction quality with reduced solvent content. Only the classical R state has been so far observed in liganded horse hemoglobin. The state characterized in the present study lies in between the R state and the R2 state characterized earlier in liganded human hemoglobin. The results presented here, along with those of earlier studies, suggest that relaxed and tense hemoglobin ...
Comparison of two techniques for injection of the podotrochlear bursa in horses. To compare accuracy of 2 methods for injection of the podotrochlear bursa in horses. Methods: Observational study. Methods: 17 French Standardbreds. Methods: In each horse, contrast medium was injected into the podotrochlear bursa of 1 foot by use of a distal palmar approach with the needle inserted parallel to the sole (DPPS) and into the podotrochlear bursa of the other foot by use of a distal palmar approach to the navicular position (DPNP). Podotrochlear bursa injection was evaluated by means of radiographic examination in all horses and postmortem examination in 6. Results: Contrast mediu...
Arthrodesis of the equine proximal interphalangeal joint: a mechanical comparison of 2 parallel 5.5 mm cortical screws and 3 parallel 5.5 mm cortical screws. To compare the biomechanical characteristics and mode of failure of 2 techniques using parallel 5.5 mm screws for pastern joint arthrodesis in horses. Methods: Randomized block design, for horse (1-5), method of fixation (two 5.5 mm screws versus three 5.5 mm screws), side (right, left), and end (front, hind). Constructs were tested to failure in 3-point bending. Methods: Twenty limbs (5 cadavers). Methods: A combined aiming device was used to facilitate screw placement. Two parallel 5.5 mm screws were inserted in lag fashion in 1 limb of a pair, and three 5.5 mm screws were inserted in the co...
Neovascularisation in chronic tendon injuries detected with colour Doppler ultrasound in horse and man: implications for research and treatment. Recent research on chronic painful Achilles tendons in humans using ultrasonography and immunohistochemistry, has demonstrated an association between neurovascular ingrowth and tendon pain. In horses, chronic debilitating tendon conditions are well-known to be very difficult to treat, and the background to impaired function and pain is not scientifically clarified. In a collaborative research project between the Sports Medicine Unit in Umeå and Strömsholm Equine Hospital, grey-scale ultrasonography (US) and colour Doppler (CD) examination were performed in ten horses with chronic tendon inju...
Kerr-gated time-resolved Raman spectroscopy of equine cortical bone tissue. Picosecond time-resolved Raman spectroscopy in equine cortical bone tissue is demonstrated. Using 400-nm pulsed laser excitation (1 ps at 1 kHz) it is shown that Kerr cell gating with a 4-ps window provides simultaneously time-resolved rejection of fluorescence and time-resolved Raman scatter enabling depth profiling through tissue. The Raman shifts are the same as those observed by conventional cw Raman spectroscopy using deep-red or near-infrared lasers. The time decay of Raman photons is shown to fit an inverse square root of time function, suggesting propagation by a diffusive mechanism. U...
Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 8. Quantitative back-scattered electron scanning electron microscopy and confocal fluorescence microscopy of the epiphysis of the third metacarpal bone. To characterise and explain the increase in density evident by computerised tomography (CT) and radiography in companion studies as a response to training, in bone in the palmar and dorsal regions of the condyles of the third metacarpal bone (Mc3) of 2-year-old Thoroughbred horses. Methods: Compositional back-scattered electron (BSE) imaging in scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) were conducted on polymethyl methacrylate (PMMA)-embedded mediolateral slices of the right distal Mc3 from seven 2-year-old Thoroughbred horses trained on a racetrack and s...
Evaluation of developmental changes in the coexpression of myosin heavy chains and metabolic properties of equine skeletal muscle fibers. To determine the growth-related changes in metabolic and anatomic properties in equine muscle fiber type, including hybrid fibers identified with immunohistochemical analysis. Methods: 24 2-, 6-, 12-, and 24-month-old female Thoroughbreds. Methods: Samples were obtained from the gluteus medius muscle of all horses. Expression of myosin heavy chain (MHC) isoforms MHC-I, -IIa, -IIb, and -IIx in each muscle fiber was detected by use of 4 primary monoclonal antibodies: BA-D5, SC-71, BF-F3, and BF-35, respectively. Five muscle fiber types (types I, I/IIA, IIA, IIA/IIX, and IIX) were immunohistochem...
Functional adaptation of articular cartilage from birth to maturity under the influence of loading: a biomechanical analysis. The concept of functional adapatation of articular cartilage during maturation has emerged from earlier biochemical research. However, articular cartilage has principally a biomechanical function governed by joint loading. Objective: To verify whether the concept of functional adaptation can be confirmed by direct measurement of biomechanical properties of cartilage. Objective: Fetuses have homogeneous (i.e. site-independent) cartilage with regard to biomechanical properties. During growth and development to maturity, the biomechanical characteristics adapt according to functional (loading) de...
Deep digital flexor tendon force and digital mechanics in normal ponies and ponies with rotation of the distal phalanx as a sequel to laminitis. Previous studies have implicated tension in the deep digital flexor tendon (DDFT) in the rotation of the distal phalanx (DP) after the breakdown of the dorsal laminae caused by laminitis. Howeveer, once the DP has rotated, the DDFT should become shorter, reducing the force it exerts on the DP. Objective: To compare DDFT force and ground reaction forces (GRFs) in normal ponies and ponies with rotation of the DP as a sequel to laminitis. Methods: Six normal ponies (Group 1) and 6 sound ponies with 6-13 degrees of rotation of the DP in relation to the dorsal hoof wall (Group 2) were assessed at t...
Digital cushions in horses comprise coarse connective tissue, myxoid tissue, and cartilage but only little unilocular fat tissue. Digital cushions were studied in horses with particular reference to vascularization, tissue constituents and matrix components. The cushions mainly resembled a network of coarse collagen bundles. The areas inbetween the bundles were replenished with loosely woven interstitial connective tissue, myxoid tissue, and fibrocartilage. Expected masses of fat lobules were missing: only solitary adipocytes or small groups of adipocytes were seen. Vascular supply to the cushions was remarkably poor. The mucinous myxoid matrix largely consisted of hyaluronan with little sulphated glycosaminoglycans. Myx...
Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 3. In vivo ultrasonographic assessment of the cross-sectional area and echogenicity of the superficial digital flexor tendon. To determine if the superficial digital flexor tendon (SDFT) of young Thoroughbred horses changed in size and echogenicity in association with early race training. Methods: Cross-sectional area (CSA) and echogenicity were determined ultrasonographically at five levels of the SDFT of the forelimbs of 2-year-old fillies (n=14), corresponding to 4, 8, 12, 16 and 20 cm distal to the accessory carpal bone (DACB). Measurements were made before and after a 13-week period in which a trained group of seven horses was compared with another group of seven untrained horses. Results: Level below the access...
The quantitative assessment of photodensity of the third carpal bone in the horse. To determine whether variation in x-ray-beam angle significantly affected photodensity of the third carpal bone (C3) in the horse using the tangential radiographic view, and indirectly determine whether radioabsorptiometry (RA) could be used to assess differences in bone mineral density (BMD) of C3 between exercised and non-exercised horses. Methods: The left distal carpal row was isolated post-mortem from 2-year-old Thoroughbred horses that had been either exercised (n=7) for up to 14 weeks using a standard training regimen for racehorses, or not exercised (n=7). The effect of variation in x-...
Evaluation of architectural changes along the proximal to distal regions of the dorsal laminar interface in the equine hoof. To describe architectural changes along the dorsal laminar interface of the equine foot. Methods: 6 macroscopically normal forefeet obtained from 6 equine cadavers. Methods: Histologic sections of 8 evenly spaced, proximal to distal, samples of the dorsal laminar interface were photographed, digitized, and examined for differences in architecture. Laminar depth; secondary laminar density; number and consistency of bifurcations occurring within the secondary laminae, and areas composed of primary dermal lamina, primary epidermal lamina, and secondary laminar interface were recorded. Data were e...
Overload arthrosis: strain patterns in the equine metacarpal condyle. An overload arthrosis occurs consistently in the palmar region of the metacarpal condyle of the equine fetlock (metacarpophalangeal) joint characterized by subchondral bone sclerosis, devitalization and mechanical failure leading to collapse of the overlying articular cartilage. Samples were selected of joints with mild, moderate, and severe subchondral sclerosis, in which cartilage collapse had not yet occurred. An additional group that had severe sclerosis with focal rarefaction suggesting impending collapse was also studied (n=5/group). Parasagittal slices were milled to 2.0 mm thickness an...
Effects of racetrack exercise on third metacarpal and carpal bone of New Zealand thoroughbred horses. The response of equine bone to training has not been quantified in racetrack trained horses, only in treadmill exercised horses. Seven two-year-old thoroughbred fillies were trained on sand and grass at a racetrack, in a typical New Zealand flatrace training regime. The horses were exercised 6 days per week for up to 13 weeks. During the day the horses were confined in 4 x 4m sand yards, and were stalled at night. Another 7 fillies of the same age were allowed free exercise in grass yards. The bones of the animals were available after the 13 week experimental period, and were examined using a ...
Mechanical behavior and quantitative morphology of the equine laminar junction. The horse's hoof is structurally modified for its mechanical functions, but studying the functional design of internal structures is hampered by the external keratinous capsule. Finite-element analysis offers one method for evaluating mechanical function of components within the capsule, such as the laminar junction. This is the epidermodermal connection that binds the hoof wall strongly to the distal phalanx. Primary epidermal laminae (PEL), projecting inward from the wall, vary in morphology and are remodeled despite being keratinous. The aim of this study is to investigate the suggestion th...
The role of the extrinsic thoracic limb muscles in equine locomotion. Muscles have two major roles in locomotion: to generate force and to absorb/generate power (do work). Economical force generation is achieved by short-fibred pennate muscle while the maximum power output of a muscle is architecture independent. In this study we tested the hypothesis that there is an anatomical and structural separation between the force-generating anti-gravity muscles and the propulsive (limb/trunk moving) muscles of the equine forelimb. Muscle mass and fascicle length measurements were made on the thoracic limb extrinsic muscles of six fresh horse cadavers. Physiological cros...
A review of equine dental disorders. Equine dentistry is a very important but until recently rather neglected area of equine practice, with many horses suffering from undiagnosed, painful dental disorders. A thorough clinical examination using a full mouth speculum is a pre-requisite to performing any equine dental procedure. Common incisor disorders include: prolonged retention of deciduous incisors, supernumerary incisors and overjet--the latter usually accompanied by cheek teeth (CT) overgrowths. Overjet can be surgically corrected, but perhaps should not be in breeding animals. In younger horses, traumatically fractured incis...
Distribution of sialoglycoconjugates in the oviductal isthmus of the horse during anoestrus, oestrus and pregnancy: a lectin histochemistry study. The distribution of sialic acid residues as well as other glycosidic sugars has been investigated in the horse oviductal isthmus during anoestrus, oestrus and pregnancy by means of lectin and pre-lectin methods. Ciliated cells and non-ciliated (secretory) cells exhibited different lectin binding profiles that were found to change during the investigated stages. Ciliated cells did not show any reactivity in the basal cytoplasm, while the supra-nuclear cytoplasm displayed a few of oligosaccharides with terminal and internal alphamannose (Man) and/or alphaglucose (Glc) during oestrus and pregnanc...
