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.
Multimodal Imaging to Identify and Characterize a P3 Cystic Lesion and Pathologic Fracture. Lameness remains a common cause of retirement in the equine athlete and among hobby enthusiasts. The distal limb is one of the most frequently imaged areas, and recent advances in diagnostic imaging capabilities help practicing veterinarians differentiate normal variants from informative pathology. Although acute, non-weight-bearing lameness is commonly associated with etiologies, such as fractures, abscesses, and laminitis, other uncommon differentials such as cystic lesions and neoplasia might also be considered. This report describes the characterization of a large, cystic lesion in the thi...
Correcting Campylorrhinus Lateralis in a Foal by Bone Distraction: A Case Report. Campylorrhinus lateralis, also known as "wry nose," is a congenital malformation that mainly affects Thoroughbreds. These horses have a unilateral deviation of the maxillae that may be to one side or the other side, and it causes airway obstruction and dental malocclusion. The choice of treatment is not necessarily operation; however, the treatment of choice, which aims to repair the maxillae deviation, is surgical to improve the horse's respiratory condition and correct the dental occlusion. There are currently no reports describing the first surgical technique for such deformity described by...
The Equine Gingiva: A Histological Evaluation. Equine periodontal disease in horses has long been recognized as a painful disease, leading to a poor condition. The disease is widespread and attracts growing attention in equine dental medicine. The understanding of the underlying etiological and pathological mechanisms of equine periodontal disease is necessary to develop effective prophylactic and treatment options. As a first step, a thorough description of the histological features of the healthy equine gingiva is required. Specimens were taken from six horses (3 mares, 3 geldings, age: 0.5-26 years). The animals were euthanized for reas...
Occlusal fissures in equine cheek teeth: μCT and histological findings. Fissures on the occlusal surface of equine cheek teeth are commonly encountered during oral examination. Generally, their presence is considered abnormal but their aetiopathogenesis and clinical impact on pulp disease is still undetermined. The aims of this research were to study the extent of occlusal cheek teeth fissures using high-resolution X-ray computed tomography (μCT) imaging and their histological characteristics. Twenty-seven teeth (of 15 horses) were scanned using μCT imaging to analyse fissure extent. Histological examination of a subset of teeth (n=7) was performed. Forty-three ...
Finite Element Analysis of Six Transcortical Pin Parameters and Their Effect on Bone-Pin Interface Stresses in the Equine Third Metacarpal Bone. The objectives of this study were to validate a finite element model of the equine distal limb transfixation cast and to determine the effect of six transcortical pin parameters on bone-pin interface (BPI) stresses in the third metacarpal bone. Methods: A transfixation cast finite element model was developed from a computed tomography scan of the third metacarpal bone and modelled pin elements. The model was validated by comparing strain measured around a 6.3-mm transfixation pin in the third metacarpal bone with the finite element model. The pin parameters of diameter, number, location,...
High-field (3 Tesla) MRI of the navicular apparatus of sound horses shows good agreement to histopathology. Magnetic resonance imaging and the correlation to histopathological findings of the equine palmar foot of lame horses have been described previously, using 0.27 and 1.5 T systems. Compared to these, 3 T systems provide superior spatial resolution and imaging contrast. The aim of our prospective anatomic study was to characterize the imaging anatomy of the navicular region on 3 T MRI in comparison to histopathological findings. We hypothesized that 3 T MRI allows a good visualization of the entire navicular apparatus and reliable measurements of navicular cartilage and cortical bone thickness. ...
Magnetic resonance imaging and computed tomography of equine cheek teeth and adjacent structures: comparative study of image quality in horses in vivo, post-mortem and frozen-thawed. The use of cadavers for radiology research methodologies involving subjective image quality evaluation of anatomical criteria is well-documented. The purpose of this method comparison study was to evaluate the image quality of dental and adjacent structures in computed tomography (CT) and high-field (3 T) magnetic resonance (MR) images in cadaveric heads, based on an objective four-point rating scale. Whilst CT is a well-established technique, MR imaging (MRI) is rarely used for equine dental diagnostics. The use of a grading system in this study allowed an objective assessment of CT and MRI a...
Temporal and spatial changes in bone accrual, density, and strain energy density in growing foals. Bone adaptation is in part driven by mechanical loading, and exercise during youth has been shown to have life-long benefits for bone health. However, the development of early exercise-based interventions that reduce the incidence of fractures in racing horses is limited by the lack of characterization of normal development in growing bone. Previous efforts to quantify bone development in the horse have relied on repeated radiographs or peripheral quantitative computed tomography scans, which are limited in their assessment of the entire bone. In this study, we acquired computed tomography sca...
Penetration Profiles of a Class IV Therapeutic Laser and a Photobiomodulation Therapy Device in Equine Skin. Photobiomodulation therapy (PBMT) effects depend on the energy settings and laser penetration. We investigated the penetration time profiles of two different light therapy devices, at the dark and light skin regions in horses. Six light skin and six dark skin adult clinically healthy Arab and Quarter horses were used. A cutometer was used to measure the width of the skin fold from both sides of the cervical area, followed by three measurements of the thickness of the same skin fold by transversal and longitudinal ultrasonography (US). The depth of light penetration was compared based on the pe...
Standing low-field MRI of the equine proximal metacarpal/metatarsal region is considered useful for diagnosing primary bone pathology and makes a positive contribution to case management: A prospective survey study. High-field MRI of the proximal metacarpal/metatarsal region has been associated with great diagnostic potential and clinical reports of standing low-field MRI of the forelimb suggest the same. To better understand diagnostic outcomes with standing low-field MRI of the proximal suspensory region, a prospective survey study was conducted and users of a widely available system questioned on their experience, operating procedures, and interpretation of standing low-field MRI findings. Response data included scores on a modified Likert scale from which weighted ratings were calculated for statistic...
Cephalometric Study of the Overjet Development in Warmblood Foals. Class II malocclusion is the most frequently occurring congenital malocclusion in horses. Radiographic cephalometric procedures adopted from human dentistry were used to study the development of overjet in a population of 650 Warmblood foals. Thirteen foals were diagnosed with measurable overjet at the beginning of the study. The malocclusion in nine foals resolved spontaneously and four foals without overjet at 2 weeks of age developed the condition during the first year of life. A cephalostat used in human orthodontics to immobilize the patient's head while being radiographed was replaced by...
Pododermal angioarchitecture in the equine hoof wall: A light and scanning electron microscopic study of the wall proper. Blood supply is an important factor for the normal function of the equine hoof, but earlier studies present conflicting data on functional characteristics of its angioarchitecture. Objective: Emphasis was laid on demonstration of the microvascularisation in the different hoof wall regions, aiming at assessment of specialised vascular structures, e.g. vascular sphincter mechanisms and arteriovenous anastomoses. Methods: The angioarchitecture of the adult pododerma in the equine hoof wall was examined by scanning electron microscopy of micro-corrosion casts assisted by exemplary histological and...
Histologic assessment of age-related changes in the temporomandibular joints of horses. To describe histologic changes in the temporomandibular joints (TMJs) of horses of various ages. Methods: 22 TMJs from cadavers of 11 horses. Methods: Horses were categorized into 3 age groups (group 1, 2 to 10 years old [n = 3]; group 2, 11 to 20 years old [3]; and group 3, > 20 years old [5]). Each TMJ was sectioned into 5-mm slices, preserved in formalin, decalcified in formic acid, and routinely processed for histologic analysis. Joints were systematically assessed by use of previously described methods. Multilevel mixed-effects models were used to examine the data. Results: The number of ...
Persistent Bilateral Mydriasis Associated With a Pituitary Adenoma in a Horse. Severe bilateral mydriasis and bilaterally decreased vision were observed in a 23-year-old crossbred warmblood gelding with a history of pituitary pars intermedia dysfunction. Ten years after the onset of clinical signs, it was killed humanely because of worsening of clinical signs and loss of therapeutic responsiveness. Postmortem examination of the head was performed to confirm the suspected pituitary neoplasm and to investigate secondary oculomotor lesions. Pathomorphologic examination revealed an expansile space-occupying pituitary adenoma and degenerative changes in the preganglionic ocul...
Changes in Hoof Shape During a Seven-Week Period When Horses Were Shod Versus Barefoot. This crossover study tested the hypothesis that hoof shape would differ after a seven-week period of horses ( = 11) wearing shoes versus barefoot. An ANOVA appropriate to a crossover design was used to assess the differences in the change in hoof shape over the seven-week period and significance was set at < 0.05. Results are displayed as the mean difference for horses when shod versus barefoot ± the SEM for the left (L) and right (R) front hooves. Proximal hoof circumference (PHC) decreased when horses were shod and barefoot, but this decrease was greater when horses were shod (L -0.65 ...
Sinocutaneous fistula repair with a masseter muscle transposition flap combined with wound matrix and cancellous bone graft in a horse: A new technique. To describe a new technique to repair a sinocutaneous fistula with a masseter muscle transposition flap. Methods: Case report. Methods: One 13-year-old thoroughbred stallion. Methods: One 13-year-old stallion with a 3.5 × 6-cm sinocutaneous fistula over the right caudal maxillary sinus was treated with a transpositional masseter muscle flap. This repair consisted of a commercial wound matrix dressing placed directly over the hole in the maxilla and secured with suture material; a cancellous bone graft collected from the right tuber coxa placed on the dressing; and a portion of the superfi...
Aortic, common carotid and external iliac artery arterial wall stiffness parameters in horses: Inter-day and inter-observer and intra-observer measurement variability. In human medicine, local and regional arterial wall stiffness (AWS) parameters are routinely used to assess the vascular health. In horses, information regarding reproducibility of ultrasonographically derived AWS parameters is lacking. Objective: To evaluate the inter-day and inter-observer and intra-observer measurement variability of both local and regional AWS parameters in horses. Methods: Experimental study. Methods: In 10 healthy, adult Warmblood horses, B-, M-mode and pulsed-wave Doppler ultrasound images were collected on two different days from aorta, cranial and caudal common caroti...
The Equine Hoof: Laminitis, Progenitor (Stem) Cells, and Therapy Development. The equine hoof capsule, composed of modified epidermis and dermis, is vital for protecting the third phalanx from forces of locomotion. There are descriptions of laminitis, defined as inflammation of sensitive hoof tissues but recognized as pathologic changes with or without inflammatory mediators, in the earliest records of domesticated horses. Laminitis can range from mild to serious, and signs can be acute, chronic, or transition from acute, severe inflammation to permanently abnormal tissue. Damage within the intricate dermal and epidermal connections of the primary and secondary lamellae...
Rare Finding of a Full Nuchal Ligament Lamellae With Attachment Points From C2-C7 in One Australian Stock Horse. For over 200 years, equine anatomic literature has chiefly portrayed the attachment points of the nuchal ligament lamellae (NLL) from the second to the seventh cervical vertebrae (C2-C7). However, recent studies have shown that the modern domestic horse, Equus caballus, primarily exhibits the attachments points from C2-C5. Here we present the rare finding of a complete NLL attached from C2-C7 in one Australian Stock Horse (ASH) and discuss the potential implications of these findings. Previously, this trait has only been confirmed among close descendants of Equus ferus ferus; namely the primi...
Ex vivo comparison of barbed sutures for pelvic flexure enterotomy in horses. To evaluate two different barbed sutures for closure of pelvic flexure enterotomies and compare results achieved with two previously described closure techniques. Methods: Ex vivo. Methods: Twenty-four fresh cadaver adult equine large colons. Methods: Cadavers were randomly assigned to four closure groups (n = 6 each group): single-layer absorbable suture, double-layer absorbable suture, single-layer unidirectional barbed suture, or single-layer bidirectional barbed suture. Construction time, luminal reduction (percentage), bursting pressure, and method of failure were measured. Cost, leakage,...
Radiological Evaluation of Juvenile osteochondral Conditions in Brazilian Warmblood Horse. The term juvenile osteochondral condition (JOCC) has been used to identify developmental changes in the growth plates. The condition is characterized by a set of changes with similar pathogenesis that affect the immature skeleton and joints of growing foals. The aim of the current study is to investigate the prevalence and degree of severity of osteochondral changes in Brazilian warmblood (BW) foals in two farms in the south of Brazil. Radiological evaluation was applied to the metacarpophalangeal (MCP), carpal (C), metatarsophalangeal (MTP), tarsal (T), and femorotibiopatellar (FTP) joints of...
Radiographic tracheal lumen to vertebral ratios in the normal American Miniature Horse. Tracheal collapse in horses is reportedly uncommon; however, American Miniature Horses are more commonly affected. There is no description of the tracheal luminal diameter of American Miniature Horses, making early detection of tracheal luminal narrowing difficult. Objective: To 1) describe radiographic tracheal luminal diameter in clinically normal American Miniature Horses, 2) report the prevalence of subclinical tracheal collapse in a population of American Miniature Horses, and 3) use tracheal videofluoroscopy to quantify variation in tracheal luminal diameter throughout the respiratory c...
Establishment of a model for equine small intestinal disease: effects of extracorporeal blood perfusion of equine ileum on metabolic variables and histological morphology – an experimental ex vivo study. In horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. The perfusion of isolated organs is successfully used to minimize animal testing for the study of pathophysiology in other scenarios. However, extracorporeal perfusion of equine ileum sourced from horses slaughtered for meat production has not yet been described. Therefore the pre...
Quantitative magnetic resonance imaging and histological hoof wall assessment of 3-year-old Quarter Horses. Few noninvasive methods are available for equine hoof wall evaluation. The highly organised wall structures and composition of proteoglycans and collagens may make this region amenable to quantitative MRI (qMRI) techniques of T1ρ and T2 mapping to identify pathology related to proteoglycan content and collagen organisation respectively. Objective: To establish normative T1ρ and T2 values of the equine hoof wall of 3-year-old Quarter Horses with histological comparison. Methods: Cadaveric anatomical study. Methods: Six cadaveric left thoracic feet from 3-year-old racing Quarter Horses with no...
Ex vivo evaluation of an alternative technique for resection of the proximal manica flexoria in horses. To describe and evaluate an alternative technique for tenoscopic resection of the manica flexoria (MF). Methods: Descriptive study. Methods: Equine cadaver forelimbs and hind limbs (n = 36). Methods: Three surgeons varying in experience resected the MF in 12 limbs. The procedure was divided into six steps, including resection of the lateral/medial borders of the MF with a hook knife and resection of the proximal border with a micro scalpel. Outcomes compared between surgeons included completeness of resection, appearance of the margins of resection, appearance of the resected MF, collateral da...
Investigation into pathophysiology of naturally occurring palatal instability and intermittent dorsal displacement of the soft palate (DDSP) in racehorses: Thyro-hyoid muscles fatigue during exercise. Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nin...
Sacrococcygeal luxation and complete tail amputation following a tail pull injury in a horse. A 17-year-old Quarter horse mare was presented because of traumatic luxation of the fifth sacral and first coccygeal vertebrae resulting in loss of sensation, motor function, and perfusion of the tail. The case was complicated by an associated tail head hematoma. Due to the severity of the injury, tail amputation was performed at the level of the luxation. Tail amputations in horses at the sacrococcygeal junction following a suspected tail pull injury are infrequently reported in the literature. . Une jument Quarter horse âgée de 17 ans fut présentée pour cause de luxation traumatique de l...
History, clinical findings and outcome of horses with radiographical signs of equine odontoclastic tooth resorption and hypercementosis. The progression of equine odontoclastic tooth resorption and hypercementosis (EOTRH) has not been completely evaluated, and currently, the only effective treatment is extraction of severely affected teeth. We aim to describe how the disease relates to the history and clinical findings and to report on the outcome in individual horses. This case series comprises data collected from 20 horses (age 14-29 years old) with radiographic findings of EOTRH in their incisor and/or canine teeth. Most horses affected with EOTRH in this study were admitted for dental problems, but some for other complaints...
Intrabladder pressure as predictor of intra-abdominal pressure in horses. To investigate effects of postural changes and bladder distention on intrabladder pressure whilst estimating intra-abdominal pressure in horses. Two-year cohort study. Patients admitted for elective surgical procedures unrelated to gastrointestinal or genitourinary tract. School of Agricultural and Veterinarian Sciences, Jaboticabal, SP, Brazil. 20 adult horses, 11 males (stallions and geldings) and 9 females; between 3.5 and 12 years, weighing 350 to 500 kg. Intra-abdominal pressure was directly-recorded through abdominocentesis at the ventral midline with a fluid-filled system. Intrabladder ...
Assessing pathological changes within the nucleus ambiguus of horses with recurrent laryngeal neuropathy: An extreme, length-dependent axonopathy. Equine recurrent laryngeal neuropathy (RLN) is a naturally occurring model of length-dependent axonopathy characterized by asymmetrical degeneration of recurrent laryngeal nerve axons (RLn). Distal RLn degeneration is marked, but it is unclear whether degeneration extends to include cell bodies (consistent with a neuronopathy). With examiners blinded to RLN severity, brainstem location, and side, we examined correlations between RLN severity (assessed using left distal RLn myelinated axon count) and histopathological features (including chromatolysis and glial responses) in the nucleus ambiguu...