The skeletal system in horses comprises a complex structure of bones that provide support, protection, and mobility. Equine bones are involved in various physiological functions, including mineral storage and hematopoiesis. The bone structure in horses is categorized into different types, such as long bones, short bones, flat bones, and irregular bones, each serving specific roles in movement and stability. Research in this area explores topics such as bone development, remodeling, and the impact of nutrition and exercise on bone health. This page gathers peer-reviewed studies and academic articles that focus on the anatomy, physiology, and pathology of bones in horses, offering insights into conditions such as fractures, bone diseases, and the effects of aging on the equine skeletal system.
Vivrette SL, Reimers TJ, Krook L.Hypothyroidism was diagnosed in a 5-month-old Thorough-bred colt by clinical and clinico-pathology examinations, thyroid stimulating hormone response test and by microscopic evaluation of the thyroid gland. Skeletal lesions included delayed appearance of ossification centers and delayed development of bone in cartilage models, delayed closure of epiphyseal plates, transverse trabeculation in metaphyses, osteochondrosis dissecans and subchondral cysts.
Bertone AL, Powers BE, Turner AS.An aged Thoroughbred stallion was examined because of progressive lameness, carpal swelling, and weight loss. Radiography revealed a destructive lesion in the caudomedial, distal portion of the radius. Chondrosarcoma was diagnosed by tumor-core biopsy. Gross and histologic evaluation of the neoplasm after necropsy revealed a locally invasive chondrosarcoma at the distal end of the radius that infiltrated the radiocarpal joint capsule and invaded the carpal bones. The malignant nature of this tumor was evident by its invasiveness and histologic features of cell pleomorphism and presence of mito...
Hoppe F.A total of 106 Standardbred Trotters and 27 Swedish Warmblood horses, with a radiological diagnosis of osteochondrosis dissecans, were studied over a six year period. The majority were young horses. No statistical difference in frequency between the sexes was demonstrated. In both breeds osteochondrosis was most common in the hock joints, the site of predilection being the distal dorsal tip of the intermediate tibial ridge. On radiographs the lesions of the hock joints were graded on a scale from 0 to 5 according to size, number and localisation of defects and visible loose bodies. The sizes o...
Vandeplassche M, Simoens P, Bouters R, De Vos N, Verschooten F.In 214 cases of severe dystocia in mares, of which 141 (66 per cent) were Draught horses, deviation of the head and neck, with or without torticollis, malformed head and limbs were found to be the cause of dystocia. No evidence of a genetic lethal factor was found and torticollis was often combined with scoliosis of the head and, frequently, with malformation of one or more limbs. This is considered evidence of a common aetiology and pathogenesis of the syndrome of malformation. The malformations were found to be associated with an increased incidence of caudal and, particularly, transverse pr...
Anderson GF, Landsheft B.Performance horses should be thoroughly examined before sale to detect any defects that could render them unsuitable for the purchaser's intended use. With the horse in its stall, the eyes, nasolacrimal puncta, external ear canals and mouth are examined, the rectal temperature measured and the heart, lungs, trachea and sinuses auscultated. Moving the horse out of the stall, the head, parotid glands, mandibular lymph nodes, larynx, neck muscles, jugular veins and cervical vertebrae are inspected. The scapula, point of the shoulder, withers, tuber sacrale and point of the hip are palpated, after...
McCoy DJ, Shires PK, Beadle R.Atlantoaxial subluxation secondary to odontoid fracture in a 30-day-old foal was corrected by alignment of the atlantoaxial joint and stabilization with 2 ventrally placed dynamic compression plates. At 90 days after surgery, healing of the fracture, with adequate alignment of the atlantoaxial joint, was confirmed radiographically. The foal was only slightly tetraparetic at that time. At 1 year after surgery, the gait was normal. It was concluded that the technique has advantages over the use of Steinmann's pins or external coaptation for stabilization. The ventral approach allows decompressio...
Bertone AL, Aanes WA.Three cases of unilateral congenital phalangeal hypoplasia are described in 2 horses and 1 mule. Radiographic lesions include severe hypoplasia of the 3rd phalanx, and associated hypoplasia of the 2nd phalanx in 2 cases, and hypoplasia or aplasia of the navicular bone in 2 cases. All animals could ambulate but were lame. Two cases had palpable laxity at the level of the coronary band. Documented etiology was not determined for the dysgenesis, but possibilities include inherited transmission or an environmental teratogen.
Fretz PB, Barber SM, Bailey JV, McKenzie NT.The case records of 49 horses with proximal sesamoid bone fracture were studied. The population consisted of 20 Thoroughbreds, 20 Standardbreds, 5 Quarter Horses, 2 Arabians, and 2 grade horses. The fractured bones were classified into 5 categories: apical fractures, basilar fractures, abaxial fractures, middle one-third fractures, and bilateral comminuted-distracted fractures. Apical fractures occurred most frequently in the Standardbred, with the prevalence of medial fracture being equal to that of lateral fracture. Basilar fractures occurred predominantly in the Thoroughbred, with the highe...
Fretz PB, Cymbaluk NF, Pharr JW.Long-bone growth at the distal ends of the radial bones, the distal ends of the 3rd metacarpal bones, the distal ends of the 3rd metatarsal bones, and the proximal ends of the proximal phalangeal bones (of thoracic and pelvic limbs) was quantitatively analyzed in 9 Thoroughbred-Quarter Horse foals from birth to 2 years of age. Metal growth markers were surgically implanted in the bones of the animals at 2 to 4 days of age. Radiographs of the bones were made on the day of surgical manipulation, the next day, and then once a week for 8 months, and once a month thereafter for an additional 18 mon...
Bridges CH, Womack JE, Harris ED, Scrutchfield WL.Of 8 Thoroughbred foals in which osteochondrosis developed before weaning, 7 had serum copper and ceruloplasmin concentrations below normal. Three foals on one farm had serum zinc content high enough to suggest zinc toxicosis, and the liver of each foal contained abnormally high content of zinc. Four foals from the second farm had extremely low serum copper content, but normal serum zinc content. Evidence of environmental exposure to excess zinc was not found on either farm. The lesions in the zones of endochondral ossification of the afflicted foals were similar in many respects to those foun...
Updike SJ.Tendons of insertion of the equine tibialis cranialis muscle and peroneus tertius muscle (PT) were dissected grossly. Precise areas of tendon attachment and fiber arrangements within the tendons were described for the dorsal and medial tendons of the tibialis cranialis, and for the superficial lateral, deep lateral, dorsal, and medial tendons of the PT. Direct attachment of the dorsal and medial tendons of the PT into the periosteum of the central and 3rd tarsal bones and the 3rd metatarsal bone indicates that the PT may be involved in the pathogenesis of hock lamenesses.
Bernard-Strother S, Mansmann RA, Beckstead C.A 6-month-old Quarter Horse colt, with severe left foreleg lameness of 6 weeks' duration, had swelling of the distal interphalangeal joint and a smaller-than-normal left front foot. Radiographs revealed a nondisplaced, midsagittal, intraarticular fracture of P3, which was treated with an eggbar shoe with 2 quarter clips, and stall rest for 10 weeks. The colt was sound after 10 weeks.
Schamhardt HC, Hartman W, Lammertink JL, Badoux DM.Strain tracings obtained from the tibial cortex of walking ponies reveal peaks in the principal tension and compression strains occurring immediately before and after the support phase. Evidence is presented that the presupport peak is caused by inertial forces.
Cartee RE, Rumph PF.The results from water-bath studies on equine muscle in which foreign material had been inserted and then scanned ultrasonographically were compared with the results from scanning of the muscles of horses hospitalized for diagnosis of suspected foreign objects embedded in muscle. The water-bath studies showed that bone, wood, and large tendons all will demonstrate acoustic shadowing, but that subtle differences in the characteristics of the relative hyperechogenicity and acoustic shadows facilitate elimination of certain considerations in the differential diagnosis. Ultrasonography was effecti...
Hartman W, Schamhardt HC, Lammertink JL, Badoux DM.Rosette strain gauges were bonded to the cranial, caudal, and medial surfaces of the tibia in the middiaphyseal region of 6 adult ponies. While the ponies were walking, the cranial side was mainly subjected to tension, and the caudal side, to compression. The compression strain on the caudal side was 1.5 times greater than the tension strain on the cranial side. None of these principal strains was aligned along the long axis of the bone; both deviated laterally from the long axis. On the medial surface, the principal strain deviated caudally about 40 degrees from the long axis. From analysis o...
Dik KJ.Radiographically, joint ill in foals is subdivided into four different types: Type P - osteomyelitis in the meta- and/or epiphysis adjacent to the physis. Type E - osteomyelitis in the epiphyseal subchondral bone. Type S - synovitis confined to the joint itself. Type T - osteomyelitis in the small tarsal bones. The radiographical features corresponding with the different types, the relationship between the radiological, pathological, bacterial and clinical findings, and the recommended radiographic procedure are discussed in detail.
Rubin CT, Lanyon LE.Galileo (1638) observed that "nature cannot grow a tree nor construct an animal beyond a certain size, while retaining the proportions which suffice in the case of a smaller structure". However, subsequent measurement has shown that limb bone dimensions are scaled geometrically with body size (Alexander et al., 1979a), and that the material properties of their constituent bone tissue are similar in animals over a wide range of body weight (Sedlin & Hirsch, 1966; Yamada, 1970; Burstein et al., 1972; Biewener, 1982). If, as suggested in previous scaling arguments (McMahon, 1973; Biewener, 19...
Wagner PC, DeBowes RM, Grant BD, Kaneps AJ, Watrous BJ.Proximal growth plate fractures of the tibia in 4 foals were treated surgically. A medial approach was utilized in 3 cases and a lateral approach in the fourth. Bone screw fixation was achieved with cancellous screws and washers. In 3 cases, the screw shaft crossed the proximal tibial growth plate with no adverse effects. In all animals, there was rapid and cosmetic healing. At 8 to 18 months after surgery, all horses were sound at a walk, trot, and canter.
Latimer CA, Wyman M, Diesem CD, Burt JK.The anatomy of the nasolacrimal duct of the horse was studied grossly and radiographically, using barium contrast dacryocystorhinography and methyl methacrylate casts. Radiographic contrast studies were performed on 4 specimens and gross dissections were performed on 6 specimens. Dacryocystorhinography accurately delineated the course of the nasolacrimal duct, as was subsequently demonstrated by gross dissection. A 60% barium sulfate suspension produced good radiographic contrast, allowing critical assessment of the anatomic features of the nasolacrimal duct.
Attenburrow DP, Bowring CS, Vennart W.The detection of radionuclide activity in the living equine skeleton, using bone seeking radiopharmaceuticals and a hand-held radiation detector, is reported. Pathological changes in bone can be detected and subsequent development monitored. The availability and use of this diagnostic technique in equine practice is discussed.
Mayhew IG.Arthrogryposis multiplex congenita was studied in a newborn thoroughbred foal. The syndrome affected only the left hind limb allowing the right hind limb to serve as a reference. There was a significant depletion of large motor neurons from the ventral horn of the spinal cord from L3 to S4 on the affected side. Hypoplasia of nerves, muscles, and bones was present in the affected limb. Histologically, hypoplasia and degeneration of myofibers and nerve bundles were seen. No cause of the syndrome, which corresponds to most human cases, was determined. Neuromuscular arthrogryposis was diagnosed be...
Moore JN, Mcilwraith CW.Two cases of osteochondrosis are presented. Lesions involving the lateral trochlear ridge of the femur are demonstrated on conventional radiographs and double-contrast arthrograms. A radiographic suggestion of osteochondrosis lesions in the patella is noted. Post mortem examination of one case confirmed the presence of partially free cartilaginous flaps. Reference is made to familial tendency to osteochondrosis in man, dog, pig and horse. The significance of rapid growth rate in the pathogenesis of the condition is also discussed.
Barneveld A.The pathogenesis of bone spavin and its implications for diagnosis and therapy are reviewed. The pathogenesis of spavin can be divided into three phases, which are characterised by fibrillation of cartilage, osteolysis and ankylosis respectively. It will depend on the degree of osteolysis whether diagnostic anaesthesia should be added to standard clinical and radiological examinations. Satisfactory results of treatment in the group of patients with severe osteolysis can only be obtained by arthrodesis of the distal tarsal joints. It is expected that biomechanical investigations will provide a ...
Dewes HF.Fractures of the central tarsal and/or third tarsal bones involving both limbs of six foals are described. Five of the subjects were born either premature or of twin pregnancies. Fractures occurred in the neonatal period and coincided with disablement. Features of behaviour, posture and gait are described, together with gross radiographic findings, bone ash determination and blood chemistry. Lesions observed on the articular faces of tarsal bones recovered from adult horses may have originated during the neonatal-period.
Kafarnik C, Donaldson D, Payne R, Holloway A.A 13-year-old cob mare was presented with exophthalmos and periocular swelling of the left eye. The diagnostic work-up included ocular ultrasound, sonographic examination through the thinned frontal bone, radiography, standing computed tomography of the skull and exploratory osteoplastic surgery. Histopathology was consistent with an organized hematoma. An intradiploic hematoma of the frontal bone was diagnosed 5 years after head trauma, with progressive expansion and deformation of the skull resulting in exophthalmos. Exophthalmos with facial bone deformation was the only clinical finding of ...
Podadera JM, Bell RJ, Dart AJ.Two horses presented with a history of severe lameness that was localised to the area around the second phalanx (P2) of one forelimb. Radiographs of the second phalanx of both horses were unremarkable, apart from some smooth periosteal new bone production on the dorsum of P2. Magnetic resonance imaging revealed a non-displaced fracture of P2 in both horses. One horse was euthanased because of a poor prognosis for racing, but the second horse was treated conservatively and salvaged for breeding. Magnetic resonance imaging is a newer imaging modality in horses and may be useful in diagnosing cas...
Spoormakers TJP, Veraa S, Graat EAM, van Weeren PR, Brommer H.Data on equine thoracic pathology hardly exist in breeds other than Thoroughbreds. Objective: To describe pathological changes of the osseous thoracic vertebral column in Warmblood horses, Shetland ponies and Konik horses, and to compare prevalence and severity. Methods: Descriptive post-mortem study. Methods: Computed tomography was used to examine the thoracic vertebral column of 34 Warmblood horses, 28 Shetland ponies, and 18 Konik horses. Osteoarthritis (OA), periarticular osteolysis, osseous cyst-like lesions and fragments of articular processes (APJs), costovertebral and costotransverse ...
Power J, Hernandez P, Wardale J, Henson FM.Osteochondrosis (OC) is a common and clinically important joint disease that occurs in many species, including humans, pigs, chickens and horses. It has been described as a focal failure of endochondral ossification (EO), but no cellular/molecular mechanisms are fully described that explain the cause of this condition. Recently a Wnt signalling inhibitor, sclerostin, has been described in osteoarthritic cartilage, where it has been proposed to protect damaged cartilage from degradation. Cartilage degradation is a key event in EO, thus, abnormalities of sclerostin in growth cartilage could, pot...
Firth EC, Goedegebuure SA, Dik KJ, Poulos PW.Nine foals with haematogenous osteomyelitis of the tarsal bones were studied clinically, radiologically and pathologically. Clinical examination, including aspiration of articular or periarticular effusions in the tarsal area, and radiological study provide definitive diagnosis in most cases.
Scheidegger E, Geissbühlerl U, Doherr MG, Lang J.Bone scintigraphy is a very sensitive diagnostic tool to detect elevated bone metabolism. In cases of fractures and fissure fractures, the radiopharmaceutical uptake in the bone is said to be increased within a few hours after the injury. In this retrospective study, the scintigraphic uptake characteristics at the fracture site of 36 horses with radiographically confirmed fractures or fissure fractures were evaluated. Uptake ratios between the fracture region and adjacent normal bone or soft tissue activity respectively were calculated and compared to different anamnestic and radiographic data...
Van Wulfen KK, Bowker RM.To localize substance P (SP) and neurokinin A (NKA) and their receptors in the insertion of the distal sesamoidean impar ligament (DSIL), deep digital flexor tendon (DDFT), and dorsal hoof wall of healthy feet of horses. Methods: 18 healthy feet from horses. Methods: Samples from the dorsal hoof wall and insertion of the DSIL and DDFT of 10 feet were processed for immunocytochemical analysis, using rabbit polyclonal antisera raised against SP and NKA. Tissue sections from 8 feet were incubated with 125-labeled SP to localize tachykinin receptors and their specificity and with control solutions...
Mageed M, Dyab S, Swagemakers JH, Gerlach K.The impact of different acquisition times (AqT) and technetium-99 m-labeled ( Tc) diphosphonates on the image quality of bone scintigraphy is poorly documented in horses. The aim of this prospective experimental study was to evaluate the impact of varying Tc-disphosphonates and AqT on semiquantitative and qualitative image parameters of bone scintigraphy in horses. Twenty-four horses undergoing bone scintigraphy were divided equally and randomly into methylene- (MDP), hydroxymethylene- (HDP), and dicarboxypropane diphosphonate (DPD) groups. Lateral scintigraphic images of the antebrachium we...
Davidson EJ, Martin BB.Stress fracture of the scapula in two horses is described. Both horses had a history of acute lameness after strenuous exercise. Using elective nuclear scintigraphy focal increased radiopharmaceutical uptake in the affected scapula consistent with a fracture was identified. Standing radiography was nondiagnostic in both horses. Ultrasonographic findings in one horse were consistent with a minimally displaced incomplete fracture. Both horses were treated conservatively and returned to train and race successfully postinjury. Veterinary
Gaul CE, Rich AF, Ressel L, Hinnigan GJ, Owen KR.This study aimed to determine whether a true synovial structure exists over the olecranon tuberosity, which could be attributed to a noninflamed olecranon bursa. Contrast radiography, gross anatomical dissection, and histopathology were used to evaluate the olecranon bursa in horses with no previous elbow pathology. The radiographic study revealed that the contrast was positioned subcutaneously, superficial to the long head of the triceps and its insertion on the olecranon tuberosity and did not extend cranial to the triceps tendon. The contrast region was consistent in shape, size, and locati...
Auer JA, Watkins JP.In recent years fracture fixation in the horse has changed significantly. New devices, mainly adapted from the human field, have been successfully introduced into large animal surgery. Examples of such implants include the DCS/DHS implant system, the self-tapping screw, the cannulated screw, and the pinless external fixator. However, new devices have also been developed exclusively for equine fracture management, including the interlocking intramedullary nail and the external skeletal fixation device. With these devices the surgeon has more options for repairing fractures in horses. Neverthele...
Stolk PW, de Waal Malefijt MC, Buma P, Barneveld A.In this paper the successful replacement of an equine metatarsophalangeal joint by a human total condylar knee prosthesis is reported. In the period of observation following implantation of the endoprosthesis the experimental animal showed almost no lameness when exercised at walk, bearing weight on the operated limb. Flexion and extension of the joint were markedly reduced. The clinical and histological observations clearly support further investigation into the equine metatarsophalangeal joint replacement by an endoprosthesis.
Gaschen L, LeRoux A, Trichel J, Riggs L, Bragulla HH, Rademacher N, Rodriguez D.The magnetic resonance (MR) imaging findings of foals with infectious and noninfectious arthritis are described. Six foals with infectious arthritis and three foals with noninfectious arthritis were grouped based on synovial fluid analysis results and examined with radiography and MR imaging. Four out of six foals with infectious arthritis had osseous lesions in MR images indicative of osteomyelitis and only 4/19 lesions were detected on digital radiographs. The three foals with noninfectious arthritis had no osseous lesions in MR images or radiographically. Of the six joints that had osseous ...
Greet TR.The case histories of three young thoroughbred racehorses with displaced lateral condylar fractures combined with an axial fracture of the lateral sesamoid bone are described. In two cases the condylar fracture was repaired surgically but both horses developed severe degenerative joint disease and remained lame. The third horse was destroyed humanely. It is important that axial fractures of the sesamoid bone are recognised so that a poorer prognosis can be given for treatment of condylar fractures in racing thoroughbreds.
Greene EA, Smith KR, Pendergraft JS, Raub RH, Arns MJ.When the decision was made to euthanatize an acutely laminitic Thoroughbred broodmare, graduate students from the Department of Animal Sciences and Industry reconstructed the skeleton for use as a teaching tool. The reproductive and gastrointestinal tracts were removed and preserved in formalin. The hide, muscle, tendons, ligaments, and organs were removed, and the bones were boiled in water for > or = 48 h to remove all remaining tissue. After boiling, the bones were soaked in gasoline to remove fat from the marrow cavities and then soaked in a bleach/detergent mixture as a final cleaning ...
Martens P.An ossicle associated with the palmar aspect of the carpus is described in five horses. The size of the ossicle varied from 3 x 4 mm to approximately 12 x 10 mm. The ossicles were located at the junction of the proximal and distal rows of carpal bones, between the palmaromedial aspect of the fourth carpal bone and the ulnar carpal bone. In 3 horses they were bilateral, in one horse unilateral, and only one limb was examined in the remaining horse. In all horses it was an incidental finding and not regarded to be a pathologic entity.
Nottle BF, Tatarniuk DM, Caldwell FJ, Bell CD, Caston SS, Merkatoris PT, Gillen AM, Katzman SA.To describe the presentation, diagnosis, treatment, and outcome for horses with fibro-osseous lesions of the craniofacial complex. Methods: Retrospective multicenter case series. Methods: Thirty horses evaluated for fibro-osseous lesions of the skull from January 1, 2001 through December 31, 2019 in four centers. Methods: Medical records were reviewed for signalment, clinical presentation, histological and diagnostic imaging findings, treatment instituted, and outcome. Long-term outcome information was obtained by owner questionnaire or the medical record. Results: Diagnoses included ossifying...
Firth EC, Goedegebuure SA.The long bone ends of foals with infectious disease were sawn into sagittal slabs, washed and inspected. Tissue suspected to be abnormal on the basis of change of colour and consistency was radiographed, and then decalcified and examined histologically. The exact site of 140 focal osteomyelitis lesions from 18 foals was determined. There were more lesions in the epiphysis than the metaphysis. Epiphyseal lesions were in specific sites within a given epiphysis, and in most epiphyses the lesions were at the site of thickest cartilage. Metaphyseal lesions in the metacarpal, metatarsal and distal r...
Lang A, Brucker P, Ludwig M, Wrede T, Theunert J, Gasse H.The topographical correlations between certain extracranial and intracranial osseous points of interest (POIs), and their age-related changes, are indispensable to know for a diagnostical or surgical access to intracranial structures; however, they are difficult to assess with conventional devices. In this pilot study, the 3-dimensional coordinates of extra-/intracranial POIs were determined, thus avoiding perspective distortions that used to be intrinsic problems in 2-dimensional morphometry. The data sets were then analysed by creating virtual triangles. The sizes, shapes, and positions of t...
Frei S, Geyer H, Hoey S, Fuerst AE, Bischofberger AS.To determine scapular cortex thickness, distal scapular bone density and describe the exact suprascapular nerve course to evaluate the best plate position for the fixation of supraglenoid tubercle fractures in horses. Methods: Twelve equine cadaveric shoulders were examined with computed tomography. Computed tomography morphometry and density measurements (Hounsfield units [HU]) of the scapula were recorded. Statistical comparisons were made between the cranial and caudal aspects of the scapula. Dissection of each shoulder was performed and the suprascapular nerve course was described morphome...
Wilson DG, Trent AM, Crawford WH.A surgical approach to the ramus of the mandible was developed. Subperiosteal elevation of the masseter muscle from the ramus allowed reduction and plate fixation of ramus fractures in a bull and a horse. Results of follow-up examinations, 2 years after surgery, showed excellent functional and cosmetic results.
Boorman S, Boone L, Weatherall K, Caldwell F.A 7-year-old American Quarter Horse gelding was referred to the JT Vaughan Large Animal Teaching Hospital at Auburn University, College of Veterinary Medicine, for an investigation of a recurrent swelling of the nasofrontal region. Computed tomography examination of the skull was most consistent with a sequestrum of the left nasofrontal suture with associated focal osteomyelitis and left conchofrontal sinusitis. Surgery to remove the sequestrum, debride the devitalized bone, and flush the left conchofrontal sinus was performed. A microbial culture was obtained at the time of surgery, which yie...
