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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.
In vitro biomechanical comparison of dynamic compression plates with a rough contact surface and a polished contact surface for fixation of osteotomized equine third metacarpal bones. To compare the number of cycles to failure of 4.5 mm broad dynamic compression plates (DCP), 4.5 mm broad limited-contact dynamic compression plates (4.5-LC-DCP), and 5.5 mm broad limited-contact dynamic compression plates (5.5-LC-DCP) having a rough (denoted by a prefix R-) versus a standard smooth contact surface for the fixation of osteotomized equine 3rd metacarpal (MC3) bones. Methods: Experimental. Methods: Fifteen pairs of adult equine cadaveric MC3 bones. Methods: Fifteen pairs of equine MC3 were divided into 3 test groups (5 pairs each) for comparison of (1) R-DCP fixation with DCP fi...
The impact of ultrasound during emergency after-hour admissions of horses. Clinical use of diagnostic ultrasound at point-of-care or emergency situations, although common, has not been well documented in veterinary medicine. Medical records of after-hour emergency equine admissions during a 10-year period were reviewed and horses that received ultrasound scans were identified. Data sheets for each ultrasound scan performed during emergency clinical evaluation were collected and reviewed. Data extracted included anatomical region imaged, body system affected, documented ultrasonographic diagnosis and final diagnosis. Six hundred and nine records were available of whic...
Toxic equine parkinsonism: an immunohistochemical study of 10 horses with nigropallidal encephalomalacia. Chronic ingestion of yellow star thistle (Centaurea solstitialis) or Russian knapweed (Acroptilon repens) causes nigropallidal encephalomalacia (NPE) in horses with an abrupt onset of neurologic signs characterized by dystonia of lips and tongue, inability to prehend food, depression, and locomotor deficits. The objectives of this study were to reexamine the pathologic alterations of NPE and to conduct an immunohistochemistry study using antibodies to tyrosine hydroxylase and α-synuclein, to determine whether NPE brains show histopathologic features resembling those in human Parkinson disease...
A mechanical comparison of equine proximal interphalangeal joint arthrodesis techniques: an axial locking compression plate and two abaxial transarticular cortical screws versus an axial dynamic compression plate and two abaxial transarticular cortical screws. To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow locking compression plate (ELCP) using 5.0 mm locking screws and 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (ELCP-TLS) with an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) for equine proximal interphalangeal (PIP) joint arthrodesis. Methods: Experimental. Methods: Cadaveric adult equine forel...
Evaluation of four techniques for injecting the trochanteric bursa of horses. To describe the anatomic features of the equine trochanteric bursa and to evaluate 4 techniques for bursa centesis. Methods: Prospective, randomized design. Methods: Equine cadavers (n=2) and 20 live horses. Methods: The trochanteric bursae of 2 equine cadavers were injected with latex to identify the boundaries of the bursae. Four techniques for centesis of the trochanteric bursa were evaluated by attempting to inject dye into both trochanteric bursae of 20 live horses. Techniques included injection of the bursa with the limb-bearing weight and injection with the limb nonweight bearing and su...
Spinal epidermoid cyst in a SJL mouse: case report and literature review. This report is the first description of a spinal epidermoid cyst (EC) in a SJL mouse and gives an overview on the occurrence of ECs in animals including dogs, horses, mice and rats. The EC was not detected grossly and the mouse did not display clinical signs or an altered rotarod performance. Microscopically, there was an oval cyst lined by stratified squamous epithelium that was attached to the dorsolateral meninges and caused moderate compression of the adjacent lumbar spinal cord. ECs in mice and rats are mainly located in the caudal part of the spinal cord with a variable, strain-dependent...
An investigation of the relationships between angles and shapes of the hoof capsule and the distal phalanx. There is little scientific evidence to support the premise that poor foot conformation predisposes to foot pain and lameness. Objective: To determine relationships between external characteristics of the hoof capsule and angles of the distal phalanx; to determine variability in shape of the distal phalanx; and to investigate association between distal phalanx angles and the injury causing lameness. Methods: Feet were documented photographically and radiographically. Linear and angle measurements were obtained for the hoof capsule and distal phalanx and compared statistically. Horses were categ...
High-field magnetic resonance imaging investigation of distal border fragments of the navicular bone in horses with foot pain. Distal border fragments of the navicular bone can be seen in lame and nonlame horses and their clinical significance remains open to debate. Objective: To describe the magnetic resonance imaging (MRI) appearance of distal border fragments and the adjacent navicular bone. To investigate the relationship between fragments and other abnormalities of the navicular bone and the distal sesamoidean impar ligament (DSIL). Methods: Horses were included if pain causing forelimb lameness was localised to the foot and high-field MR images were acquired. The size and location of distal border fragments wer...
Feasibility of the Ussing chamber technique for the determination of in vitro jejunal permeability of passively absorbed compounds in different animal species. The aim of this study was to assess the feasibility of the Ussing chamber technique for the determination of the jejunal permeability of passively absorbed, high permeability model compounds (acetaminophen and ketoprofen) in different animal species. Additionally, electrophysiological measurements and histological examination of pre- and post-incubation tissue specimens were performed. Apparent permeability coefficients of turkey and dog jejunum were low and highly variable due to tissue fragility caused by differences in thickness of the remaining intestinal layers after stripping and resulti...
Quantitative motor unit action potential analysis in 2 paraspinal neck muscles in adult Royal Dutch Sport horses. Reference values for quantitative electromyography (QEMG) in neck muscles of Royal Dutch Sport horses are lacking. Objective: Determine normative data on quantitative motor unit action potential (QMUP) analysis of serratus ventralis cervicis (SV) and brachiocephalicus (BC) muscle. Methods: Seven adult normal horses (mean age 9.5 standard deviation [SD] ± 2.3 years, mean height 1.64 SD ± 4.5 cm, and mean rectal temperature 37.6 SD ± 0.3°C). Methods: An observational study on QMUP analysis in 6 segments of each muscle was performed with commercial electromyography equipment. Measurements wer...
Extraction of fractured cheek teeth under oral endoscopic guidance in standing horses. To evaluate a technique for oral extraction of fractured cheek teeth (CT) under oral endoscopic guidance. Methods: Case series. Methods: Horses (n = 30) with fractured CT. Methods: Medical records (April 2007-August 2010) of horses that had standing oral extraction of fractured CT under endoscopic guidance were reviewed. Results: Thirty horses (median age, 11.5 years; range, 5-23 years) had 31 fractured CT (21 maxillary, 10 mandibular) removed. Midline sagittal fractures of maxillary teeth (n = 13; 42%) were the most common type, followed by buccal or palatal (10; 32%), and transverse or multi...
Computed tomographic anatomy of the equine stifle joint. To provide a detailed computed tomography (CT) reference of the anatomically normal equine stifle joint. Sample-16 hind limbs from 8 equine cadavers; no horses had evidence of orthopedic disease of the stifle joints. Methods: CT of the stifle joint was performed on 8 hind limbs. In all limbs, CT was also performed after intra-articular injection of 60 mL of contrast material (150 mg of iodine/mL) in the lateral and medial compartments of the femorotibial joint and 80 mL of contrast material in the femoropatellar joint (CT arthrography). Reformatted CT images in the transverse, parasagittal, an...
Effect of differences in tendon properties on functionality of the passive stay apparatus in horses. To determine the effect of differences in structural and mechanical tendon properties on functionality of the passive stay apparatus in horses. Methods: 5 forelimbs each from nondwarf Friesians, dwarf Friesians, and ponies. Methods: Harvested forelimbs were loaded to test the passive stay apparatus. Tendons that stabilize the distal portion of the limb (superficial digital flexor tendon, deep digital flexor tendon, and tendo interosseus [suspensory ligament]) were isolated, and force-elongation data were obtained. Bone lengths, initial tendon lengths, and initial tendon cross-sectional areas w...
Gas-Filled Intradural Cyst within the Cauda Equine. A case of radicular pain that resulted from a gas-filled intradural cyst in an 80-year-old male is described. Temporary improvement of radicular pain was observed after CT-guided aspiration. However, recurrent radicular pain led to surgical treatment. In this report, the authors document the radiologic and intraoperative features of a gas-filled intradural cyst that migrated into the nerve root, and propose an optimal treatment plan based on a review of the literature.
Ultrasonographic evaluation of the coxofemoral joint region in young foals. The purpose of this study was to map the coxofemoral region in foals to obtain ultrasonographic reference values for the interpretation of potentially pathological findings in hip joints. Using a 7.5 MHz linear transducer, 38 examinations were carried out: 10 (20 joints) on cadavers and 28 (55 joints) on live healthy foals up to 8 weeks of age. The chosen plane of examination was caudolateral-craniomedial oblique on an imaginary line connecting the greater trochanter and the cranial edge of the tuber sacrale. The relatively thin muscular layer covering the coxofemoral joint allowed good image ...
Equine laminitis: comparative histopathology 48 hours after experimental induction with insulin or alimentary oligofructose in standardbred horses. Laminitis has many triggers and comparing the histopathology of lesions induced by different causes may help to establish whether a common mechanism or multiple pathologies are involved. The aim of this study was to describe the microscopical lesions and to quantify morphometric changes in the lamellae of horses with insulin-induced (n=4) and oligofructose (OF)-induced laminitis (n=4) compared with normal controls (n=4). Archived lamellar samples collected during two previous studies were used. Laminitis was induced within 48 h in standardbred horses with either a euglycaemic, hyperinsulinaemi...
Comparison of medial and lateral ultrasound-guided approaches for periarticular injection of the thoracolumbar intervertebral facet joints in horses. To compare ultrasound-guided lateral and medial approaches for periarticular injections of the thoracolumbar intervertebral facet joints (IFJ). Methods: Experimental cadaveric study. Methods: Adult equine cadavers (n=4). Methods: IFJ (T12-T13 to L5-L6) were identified by ultrasound (transducer perpendicular to the spine axis) and insertion of a 13 cm, 18 g spinal needle monitored until bone contact using medial (right side) and lateral (left side) approaches. Number of needle insertions at each site, needle repositioning, and insertion depth were recorded. On bone contact 2 mL latex was ...
Dynamic mobilisation exercises increase cross sectional area of musculus multifidus. In human subjects with back pain, the deep spinal stabiliser m. multifidus is inhibited ipsilaterally leading to atrophy, asymmetry and intervertebral instability. Specific physiotherapeutic exercises are required to reactivate m. multifidus. This study assesses the effect of dynamic mobilisation exercises on size and symmetry of m. multifidus in the equine caudal thoracic and lumbar spine. Objective: Regular performance of dynamic mobilisation exercises over a period of 3 months increases cross sectional area (CSA) and left-right symmetry of m. multifidus muscles in the caudal thoracic and lu...
Morphological spectrum of primary epidermal laminae in the forehoof of Thoroughbred horses. Hoof health is a major concern of horse owners as well as the equine industry. However, many questions remain concerning regional variations of laminar junction and its potential to remodel. Objective: To examine regional variations in the morphology of the laminar junction and thickness of the hoof wall in Thoroughbred horses. Methods: The forefeet of 25 Thoroughbred cadavers were examined. Each hoof was divided into 20 blocks through 4 proximodistal slices (below the coronary band, each 1 cm apart) and 5 circumferential positions (toe, medial and lateral quarters and heels). In each block, 2...
Hypothalamic-pituitary gland axis function and dysfunction in horses. Hypothalamic-pituitary (HP) dysfunction has been documented in a limited capacity in horses and foals associated with critical illness, stress, and pain. This article reviews species-specific details of anatomy, function, hormones, receptors, and testing of the HP axis in the horse. A discussion of critical care medicine relevant to HP dysfunction in the horse with some reference to current understanding in human medicine is made, focusing primarily on current and relevant literature. A brief mention of other conditions described in human and veterinary medicine is also provided for reference ...
Partial ostectomy of the dens to correct atlantoaxial subluxation in a pony. To report a surgical technique that allows decompression and anatomic re-alignment for management of subluxation of the atlantoaxial articulation. Methods: Clinical report. Methods: Four-year-old Welsh Section B pony gelding. Methods: Attempts at closed reduction of subluxation of the atlantoaxial articulation under general anesthesia were unsuccessful, so a ventral surgical approach allowing partial ostectomy of the dens of the axis was used to facilitate reduction. Results: Recovery from surgery was uneventful and the pony remained comfortable without neurologic deficits. Both neck stiffness...
Evaluation of a minimally invasive arthrodesis technique for the carpometacarpal joint in horses. To evaluate a minimally invasive technique for arthrodesis of the carpometacarpal (CMC) joint in horses. Methods: Experimental study. Methods: Healthy horses (n=6). Methods: A 5.5 mm, 3-drill tract arthrodesis technique was evaluated in 1 randomly selected CMC joint in each of 6 normal horses. Peak vertical ground reaction force (GRF) values were recorded before surgery and at 6, 8, and 12 months thereafter. Radiographic and clinical lameness scores were assigned at regular intervals until 12 months after surgery when the horses were euthanatized. Gross and histologic examinations were perfo...
Decreased expression of p63, a regulator of epidermal stem cells, in the chronic laminitic equine hoof. Abnormal epidermal stem cell regulation may contribute to the pathogenesis of equine chronic laminitis. Objective: To analyse the involvement of p63, a regulator of epidermal stem cell proliferative potential, in chronic laminitis. Methods: Epidermal tissues from skin, coronet and lamellae of the dorsal foot were harvested from 5 horses with chronic laminitis and 5 control horses. Tissues were analysed using histopathology, immunofluorescence microscopy and quantitative immunoblotting. Results: Hoof lamellae of laminitic horses had a lower frequency of p63 positive cells than control lamellae,...
The effect of hoof angle variations on dorsal lamellar load in the equine hoof. In the treatment of laminitis it is believed that reducing tension in the deep digital flexor tendon by raising the palmar angle of the hoof can reduce the load on the dorsal lamellae, allowing them to heal or prevent further damage. Objective: To determine the effect of alterations in hoof angle on the load in the dorsal laminar junction. Methods: Biomechanical finite element models of equine hooves were created with palmar angles of the distal phalanx varying from 0-15°. Tissue material relations accounting for anisotropy and the effect of moisture were used. Loading conditions simulating t...
Comparison of three methods of injecting the proximal interphalangeal joint in horses. The efficacy of three methods of injecting the equine proximal interphalangeal (pastern) joint was compared using cadaver limbs. Five veterinary students without prior experience attempted to inject an aqueous radiographic contrast medium into the joint using five limbs for each technique. The number of attempts was recorded and successful injection of the joint was confirmed by the presence of intra-articular contrast on radiographic examination. Levels of accuracy for the dorsal, dorsolateral and palmaroproximal approaches were 32, 48 and 36 per cent, respectively. There was inadvertent inje...
