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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.
Measurement of equine laminar blood flow and vascular permeability by use of dynamic contrast-enhanced computed tomography. To define the reference range for laminar blood flow (BF) and vascular permeability (VPM) in horses without laminitis by use of dynamic contrast-enhanced computed tomography (CT). Methods: 9 adult horses that were not lame and had no abnormalities of the laminae or phalanges detectable via radiographic examination. Methods: Each horse was anesthetized by use of a routine protocol. Horses were placed in right or left lateral recumbency with the dependent forelimb in the CT gantry; only 1 limb of each horse was scanned. Serial 10-mm collimated transverse CT images were acquired at the same locat...
Articular fetlock injuries in exercising horses. Articular injuries to the fetlock joint can be categorized as injuries to the soft tissues (synovium, ligaments, cartilage) or bone (third metacarpus/metatarsus, first phalanx, proximal sesamoids). This article focuses on the traumatic injuries to the cartilage and bone from anatomic, functional, and pathophysiological perspectives. An understanding of fetlock motion and loading will assist clinicians in the diagnosis, treatment, and, most importantly, prevention of fetlock injury in working horses.
Basic farriery for the performance horse. Proper farriery promotes a healthy functional foot and biomechanical efficiency and prevents lameness. Because the equine veterinarian is responsible for the soundness of the horse, a working knowledge of farriery becomes essential. A thorough knowledge of traditional horseshoeing enables the veterinarian to interact with the farrier at the farrier's level; this ultimately enhances and promotes quality hoof care. This article focuses on fundamental farriery and recognizing subtle changes in hoof conformation that can be used to preserve the integrity of the hoof capsule, along with the structu...
Adaptation strategies of horses with lameness. The skill to diagnose lameness in horses is paramount for every equine practitioner. Early recognition of locomotor deficiencies plays a central role in sports medicine management, preventing deterioration of the disease or catastrophic injuries. Horses use characteristic compensatory movements of specific body parts to decrease loading of the affected limb. This article describes the underlying changes in intra- and interlimb coordination and the resulting load redistribution between the limbs. This enables the practitioner to better understand the changes in movement associated with lameness...
Comparison of the microhardness of enamel, primary and regular secondary dentine of the incisors of donkeys and horses. The microhardness of the enamel, primary dentine and regular secondary dentine of seven donkey and six horse incisors was determined with a Knoop indenter at the subocclusal and mid-tooth level. The mean microhardnesses of the donkey incisor enamel, primary dentine and secondary dentine were 264.6 63.00 and 53.6 Knoop Hardness Number, respectively. There was no significant difference between the microhardness of the enamel and primary dentine on the incisors of the donkeys and horses, but the microhardness of the regular secondary dentine of the donkeys' incisors at the mid-tooth level was sli...
Tracking the motion of hidden segments using kinematic constraints and Kalman filtering. Motion capture for biomechanical applications involves in almost all cases sensors or markers that are applied to the skin of the body segments of interest. This paper deals with the problem of estimating the movement of connected skeletal segments from 3D position data of markers attached to the skin. The use of kinematic constraints has been shown previously to reduce the error in estimated segment movement that are due to skin and muscles moving with respect to the underlying segment. A kinematic constraint reduces the number of degrees of freedom between two articulating segments. Moreover...
Uterine blood flow and perfusion in mares with uterine cysts: effect of the size of the cystic area and age. Transrectal color and power Doppler ultrasonography was used to study uterine blood flow and perfusion in mares with and without uterine cysts. Vascular perfusion of the uterus and blood flow velocities, vascular perfusion, diameter, circumference, and area of a cross section of the mesometrial attachment were evaluated. To study the effect of internal cysts, two matched groups (cystic and control, n=21 mares/group) were used. Uterine vascular perfusion in mares with cysts was less (P<0.0001) in the cystic than the noncystic region and less (P<0.0009) than that for controls. Mares with c...
Fracture configurations of the equine radius and tibia after a simulated kick. The objective of this postmortem study was to determine the fracture configurations of the equine radius and tibia after a simulated kick. Fracture configurations of 35 radii and 36 tibiae from 19 adult horses were evaluated after a simulated kick in an experimental ex-vivo study. The bones were dissected, the proximal and distal ends were embedded in resin, fixed horizontally and preloaded in compression, and a steel impactor, designed to simulate a shod equine hoof, was dropped from a height of three to six metres onto the diaphysis. The experiments were filmed with a high-speed camera (30,0...
Development of equine upper airway fluid mechanics model for Thoroughbred racehorses. Computational fluid dynamics (CFD) models provide the means to evaluate airflow in the upper airways without requiring in vivo experiments. Objective: The physiological conditions of a Thoroughbred racehorse's upper airway during exercise could be simulated. Methods: Computed tomography scanned images of a 3-year-old intact male Thoroughbred racehorse cadaver were used to simulate in vivo geometry. Airway pressure traces from a live Thoroughbred horse, during exercise was used to set the boundary condition. Fluid-flow equations were solved for turbulent flow in the airway during inspiratory an...
Systematic exploration of the equine tarsus by ultrasonography. The authors propose a standard protocol of ultrasonographic exploration of the tarsal region in transversal and longitudinal planes, with the aim to spread with an accurate location of the anatomical structures. For this study, 10 adult horses of different races and ages (ranged 5-10 years) were used, with the characteristic of not having suffered any kind of tarsic pathology. The equipment was a real time ultrasound machine with a 7.5 mHz lineal transducer. Some different anatomical structures in this region of the hind-limb such as the tendons, ligaments, muscles and articular components wer...
Regionalisation of the muscle fascicle architecture in the equine longissimus dorsi muscle. The longissimus dorsi is the largest muscle in the equine back and plays an important role in locomotor ability and performance in the horse. In vivo studies suggest that the mechanical function varies between different muscle segments, in part determined by anatomy. It is possible therefore that variations in function reflect variations in the anatomy of the longissimus dorsi along its length. Objective: To identify if there are regional variations in muscle architecture of the longissimus dorsi. Methods: Computed tomography scans were obtained from 8 cadaver backs to identify the cross-secti...
Phenotypic diagnosis of dwarfism in six Friesian horses. An extreme form of abnormal development, dwarfism, is common in man and some animals, but has not been officially reported in horses. Within the Friesian horse breed, congenital dwarfism has been recognised for many years, but no detailed report exists on its phenotype. The most salient feature of the dwarf syndrome is the physeal growth retardation in both limbs and ribs. Affected animals have approximately 25% shorter fore- and hindlimbs and approximately 50% reduced bodyweight. Postnatal growth is still possible in these animals, albeit at a slower rate: the head and back grow faster than t...
Distribution of the neurokinin-1 receptor in equine intestinal smooth muscle. Tachykinins have profound effects on equine intestinal motility, but the distribution of the neurokinin receptors (NKRs) through which they act is unknown. This study reports the distribution of one of these receptors, the neurokinin-1 receptor (NK1R), in smooth muscle throughout the equine intestinal tract. Objective: To quantify the distribution of the NK1R, based upon mRNA expression, in smooth muscle of different regions of the equine intestinal tract. Methods: Nine regions of the intestinal tract were sampled in 5 mature horses. Total RNA was isolated from smooth muscle and reverse transc...
Imaging diagnosis–Intramural hematoma, jejunal diverticulum and colic in a horse. No abstract available
Surgical correction of wry nose in four horses. To describe surgical techniques used for correction of congenital nasal deviation (wry nose) in horses (wry nose) and to report outcome. Methods: Retrospective study. Methods: Horses (n=4), 5-17 months old with wry nose. Methods: Nasal deviation was corrected by transecting the premaxillae/maxillae and nasal bones at their site of maximum curvature and realigning and stabilizing the bones in a more normal alignment using internal fixation. The nasal septum was removed during the same anesthetic period. Results: For each horse, physical appearance was improved and respiratory stridor eliminated...
Assessment of the utility of using intra- and intervertebral minimum sagittal diameter ratios in the diagnosis of cervical vertebral malformation in horses. Cervical vertebral malformation is one of the most common causes of ataxia in horses. The most important factor in the diagnosis of cervical vertebral malformation is the identification of cervical vertebral canal stenosis, but published data for minimum sagittal diameter ratios in adult horses are only available for C4-C7 intravertebral sites. Intra- and intervertebral sagittal diameter ratios at C2-C7 were evaluated in 26 ataxic horses, for which a complete clinical and neuropathological evaluation was undertaken. Eight of these horses were diagnosed with cervical vertebral malformation. In ...
Osteogenic gene regulation and relative acceleration of healing by adenoviral-mediated transfer of human BMP-2 or -6 in equine osteotomy and ostectomy models. This study evaluated healing of equine metatarsal osteotomies and ostectomies in response to percutaneous injection of adenoviral (Ad) bone morphogenetic protein (BMP)-2, Ad-BMP-6, or beta-galactosidase protein vector control (Ad-LacZ) administered 14 days after surgery. Radiographic and quantitative computed tomographic assessment of bone formation indicated greater and earlier mineralized callus in both the osteotomies and ostectomies of the metatarsi injected with Ad-BMP-2 or Ad-BMP-6. Peak torque to failure and torsional stiffness were greater in osteotomies treated with Ad-BMP-2 than Ad-B...
Eustachian tube diverticulum chondroids and neck abscessation in a case of Streptococcus equi subsp. equi. A 12-year-old, grey, crossbred pony mare was presented with a swelling in the neck over the area of the 2nd cervical vertebra (C2), which was found to be painful on palpation. The neck was held stiffly. Radiography of the cervical region showed a focal area of increased radio-opacity over the dorsal, caudal and lateral aspect of the dorsal spinous process of C2. Ultrasound confirmed the presence of a hypoechoic area approximately 15 cm in diameter superimposed over the dorsal spinous process of C2. An aspirate was taken of the mass, which revealed purulent exudate confirming the diagnosis of a...
The ultrastructure of camel blood platelets: a comparative study with human, bovine, and equine cells. Previous studies indicated that the camel has a very active haemostatic mechanism with a short bleeding time and thrombocytosis. However, platelet function, when tested by agonist-induced aggregation and PFA 100 closure time, showed marked inhibition compared to humans. Since camels are also far more resistant to long exposure to excessive heat and high body temperature than humans, it seemed worthwhile to explore fundamental morphological differences between human and camel platelets and those from other species. The present study has examined the ultrastructure of camel platelets and compare...
Evaluation of equine laminar vein function: harvesting, dissection and the use of functional methods to distinguish between veins and arteries. Pharmacological evaluation of the unique equine laminar microvasculature is crucial to understanding its role in health and in diseases such as laminitis. However, separating the distinctive characteristics of arterial versus venous components of this complex vascular network has previously proved to be extremely difficult. Encased in a hard hoof capsule, isolation of individual blood vessels presents a considerable challenge. Exacerbating this difficulty, the laminar venous network is adapted to sustain high intravascular pressures and consequently has thickened walls, making the normally str...
Congenital branchial apparatus malformation in a Haflinger colt. To report the diagnosis and treatment of a branchial apparatus anomaly (BAA) associated with a mandibular malformation in a foal. Methods: Clinical report. Methods: Haflinger foal. Methods: A 6-day-old foal had a fluctuating cystic mass in the pharyngeal (throatlatch) region, which changed in appearance after ingestion of milk. Upper airway endoscopy and diagnostic imaging (ultrasonography, radiography, computed tomography) permitted identification of the anatomic location of a communicating tract between the lumen of the cystic mass and the pharynx. The mass was surgically removed and communi...
Comparison of computer assisted surgery with conventional technique for treatment of abaxial distal phalanx fractures in horses: an in vitro study. To (1) evaluate and compare computer-assisted surgery (CAS) with conventional screw insertion (conventional osteosynthesis [COS]) for treatment of equine abaxial distal phalanx fractures; (2) compare planned screw position with actual postoperative position; and (3) determine preferred screw insertion direction. Methods: Experimental study. Methods: Cadaveric equine limbs (n=32). Methods: In 8 specimens each, a 4.5 mm cortex bone screw was inserted in lag fashion in dorsopalmar (plantar) direction using CAS or COS. In 2 other groups of 8, the screws were inserted in opposite direction. Precisi...
Characteristics of collagen fibrils in the entire equine superficial digital flexor tendon. The superficial digital flexor tendon (SDFT) is one of the longest tendons in the horse. In racehorses, disturbance of the locomotor functions of the SDFT occurs most frequently in the central area of the mid-metacarpal region. While many studies have investigated the equine SDFT, there are no reports to date of the morphological characteristics of collagen fibrils in the central and peripheral areas of each of the three regions that comprise the entire tendon: the myotendinous junction (MTJ), the mid-metacarpal region (mM) and the osteotendinous junction (OTJ). Mass average diameter (MAD), wh...
Actinobacillus equuli subsp. equuli associated with equine valvular endocarditis. Microbiological and pathological data from a case of equine valvular endocarditis are reported. Limited information is available on the pathogenic potential of equine Actinobacillus species as several strains originate from apparently healthy horses. After the establishment of two subspecies within this species, this seems to be the first report of an etiological association between A. equuli subsp. equuli and equine endocarditis. Furthermore, new information on some phenotypical characteristics of this subspecies is reported, compared to previous findings.
Probing the role of water in lamellar bone by dehydration in the environmental scanning electron microscope. Water, collagen and mineral are the three major components of bone. The structural organization of water and its functions within the bone were investigated using the environmental scanning electron microscope and by analyzing dimensional changes that occur when fresh equine osteonal bone is dehydrated and then rehydrated. These changes are attributed mainly to loss of bulk and weakly bound water. In longitudinal sections a contraction of 1.2% was observed perpendicular to the lamellae, whereas no contraction occurred parallel to the lamellae. In transverse sections a contraction of 1.4% was o...
Ventral meningomyelocele in a German warmblood foal. A ventral meningomyelocele was found in a five week old, male German warmblood foal which exhibited central nervous symptoms. This rare malformation in horses may be caused by absent or defective fusion of vertebral bodies leading to herniation of the spinal cord and meninges with subsequent degenerative alterations of the spinal cord.
Benign peripheral nerve sheath tumor of the perianal region in a young pony. A 20 x 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the ...
Comparative anatomy and muscle architecture of selected hind limb muscles in the Quarter Horse and Arab. The Quarter Horse (bred for acceleration) and the Arab (bred for endurance) are situated at either end of the equine athletic spectrum. Studies into the form and function of the leg muscles in human sprint and endurance runners have demonstrated that differences exist in their muscle architecture. It is not known whether similar differences exist in the horse. Six Quarter Horse and six Arab fresh hind limb cadavers were dissected to gain information on the muscle mass and architecture of the following muscles: gluteus medius; biceps femoris; semitendinosus; vastus lateralis; gastrocnemius; tib...
Streptococcus henryi sp. nov. and Streptococcus caballi sp. nov., isolated from the hindgut of horses with oligofructose-induced laminitis. Four Gram-positive, catalase-negative, coccoid-shaped isolates were obtained from the caecum and rectum of horses with oligofructose-induced equine laminitis. Phenotypic and phylogenetic studies were performed on these isolates. Initial biochemical profiling assigned two of the isolates to Streptococcus bovis. The other two isolates, however, could not be assigned conclusively on the basis of their biochemical profiles. Gene sequence analysis demonstrated that the four new isolates were related most closely to Streptococcus suis based on the 16S rRNA gene and to Streptococcus orisratti based o...
Incidence of osteochondrosis (dissecans) in Dutch warmblood horses presented for pre-purchase examination. Data are lacking in the literature regarding the incidence of osteochondrosis (dissecans) [OC(D)] in relation to lameness evaluation in Dutch Warmblood horses. The objective of this retrospective study was to assess the incidence of radiological abnormalities consistent with osteochondrosis or osteochondrosis dissecans in 1,231 sound Dutch Warmblood (DW) horses presented for pre-purchase examination. Standardised (Dutch) pre-purchase examination protocols were evaluated. The pre-purchase examination included a clinical, lameness and radiological evaluation, performed at a private equine clinic...
