Dorsal Spinous Process Research Articles

International survey of equine orthopaedic specialists reveals diverse treatment strategies for horses with overriding spinous processes.

Overriding spinous processes, also known as 'kissing spines', are one of the most common causes of back pain in horses. The aim of this study was to investigate which options for diagnosis and treatment are preferred by equine orthopaedic specialists and assess which techniques are used for local injection. An online survey was distributed among members of the European/American College of Veterinary Surgeons, the European/American College of Veterinary Sports Medicine and Rehabilitation, the International Society of Equine Locomotor Pathology and nationally recognised advanced equine orthopaedic practitioners. The survey was completed by 353 respondents. The injection techniques most commonly used involve placing two needles abaxial to the interspinous space (42%) under ultrasonographic guidance (32%) or one needle in the midline (35%) between two spinous processes. The most popular combination for overriding dorsal spinous process therapy was local injection (26.7%) combined with controlled exercise (25.5%). Manual therapy was considered by 42% of European and 25% of American specialists (p = 0.01). Surgical intervention as a first-line treatment was recommended mainly by specialists working in the United States, the UK or Ireland (p = 0.001). Overall, most equine orthopaedic veterinarians (71%; n = 201) preferred conservative management and recommended surgery only for horses that did not respond to conservative therapy. Respondents' personal bias may have skewed the findings. Despite a growing body of evidence, the therapeutic approach to 'kissing spines' in horses is influenced by professional specialisation and regional preferences. Variations in injection techniques and differing criteria for surgical intervention warrant further investigation.

Age and sex correlate with bony changes and anatomic variations of the lumbosacroiliac region of the vertebral column in a mixed population of horses.

To provide a postmortem description of anatomic variations and changes of the lumbosacroiliac region in horses. The authors hypothesized that lesion severity would increase with age and body weight and correlate to anatomic variations. Lumbosacroiliac vertebral specimens from 38 horses (mean age, 16 years; range, 5 to 30 years) that died or were euthanized for reasons unrelated to the study between November 2019 and October 2021. The lumbosacroiliac region of the vertebral column was removed from each cadaver. After dissection, disarticulation, and boiling, the anatomic specimens were examined for anatomic variations and osseous changes of the articular process joints (APJs), intertransverse joints (ITJs), and sacroiliac joints (SIJs). The lengths of L6-S1 intertransverse articular surfaces were measured and their ratios calculated. Descriptive statistics were obtained, and the χ2 test was used to assess differences in anatomic variations and abnormal changes of the APJs, ITJs, and SIJs. The most common anatomic variation was a sacrum-like shape of the transverse processes of L6 (29/38 [76%]) and converging orientation of dorsal spinous process of L6 (33/38 [87%]). The highest prevalence of bony changes was detected at L5-L6 (right, 34/38 [89%]; left, 33/38 [87%]) and L6-S1 APJs (right, 38/38 [100%]; left, 37/38 [97%]) and at SIJs (right, 32/38 [86%]; left, 31/38 [82%]). The shape of L6 transverse processes differed between breed (P = .01) and was associated with presence of L4-L5 ITJs (P < .01). Age and sex were associated with changes of the sacral dorsal spinous processes, ITJs, and APJs. The clinical significance of these findings could not be confirmed based on the study limitations.

Taxonomic review of the genus Stenocaris Sars (Copepoda, Harpacticoida, Cylindropsyllidae), with (re)descriptions of two Stenocaris species from the Far East.

The taxonomic concept of the genus Stenocaris Sars, 1909 is uncertain because none of the synapomorphies for the species of Stenocaris are defined. Detailed comparison of previous records of Stenocaris minor (T. Scott, 1892) from different localities reveals that this species represents a species complex composed of two species, S. minor s. str. and S. minor sensu Cottarelli & Venanzetti, 1989. Because the latter species has fundamental differences in the nature of the fifth leg in females and the sexual dimorphism of the second leg in males, we propose a new species for S. minor sensu Cottarelli & Venanzetti, 1989, S. figaroloensis sp. nov. We also suggest that S. minor sensu Apostolov, 1971, S. minor sensu Marinov, 1971, and S. minor sensu Apostolov & Marinov, 1988 from the Black Sea and S. minor sensu Wilson, 1932 from North America should be relegated to species inquirenda in the genus. Taxonomic review of the morphology of all Stenocaris species indicated that the generic concept must be restricted to accommodate S. minor s. str., S. gracilis Sars, 1909, S. intermedia Itô, 1972, S. figaroloensis sp. nov., and the South Korean new species, S. marcida sp. nov., based on the synapomorphic condition of the confluent fifth leg in males. As a result of our analysis, two Stenocaris species, S. baltica Arlt, 1983 and S. pygmaea Noodt, 1955, are transferred to the genus Vermicaris Kornev & Chertoprud, 2008 as V. baltica (Arlt, 1983) comb. nov. and V. pygmaea (Noodt, 1955) comb. nov. based on the synapomorphic characters of a reduced condition of the second and fifth legs. Additionally, S. arenicola Wilson, 1932 and S. kliei (Kunz, 1938) are allocated to a new genus, Huysicaris gen. nov., mainly characterized by obvious caudal rami with a recurved dorsal spinous process and convex inner margins, as H. arenicola (Wilson, 1932) comb. nov. and H. kliei (Kunz, 1938) comb. nov. A marine interstitial harpacticoid collected from the subtidal substrate off Dok-do Island in the East Sea of South Korea is proposed as S. marcida sp. nov. and the distribution of S. intermedia, originally known from its type locality in Japanese waters only, is extended to the East Sea of Korea and Russia. We provide their detailed descriptions and illustrations and discuss the morphological characters supporting their identities.

Three-Dimensional Modeling and In Silico Kinematic Evaluation of Interspinous Ligament Desmotomy in Horses.

Background: Interspinous ligament desmotomy (ISLD) has been shown to improve the comfort of horses diagnosed with overriding dorsal spinous processes (DSP), but its effects on spine mobility are unknown. Objective: To objectively quantify the change in mobility of thoracic vertebrae following ISLD using CT and medical modeling software. Study design: Prospective cadaveric manipulation of seven equine thoracolumbar spines collected from T11-L1. Methods: Spines were collected from T11-L1 with the musculature intact. Flexion and extension phases were achieved with a ratchet device calibrated to 2000N. Bone volume CT scans were performed in resting, flexion, and extension phase preoperatively. Interspinous ligament desmotomy was performed at each intervertebral space (n = 8), and bone volume CT imaging was repeated for each phase. The spinal sections were individually segmented and imported into medical software for kinematic evaluation. T11 of each phase were superimposed, the distance between each dorsal spinous process, the total length of the spine, and the maximal excursion of the first lumbar vertebra along with angular rotational information were recorded. Results: The mean distance between each dorsal spinous process increased by 5.6 ± 4.9 mm, representing a 24 ± 21% increase in mobility following ISLD. L1 dorsoventral excursion increased by 15.3 ± 11.9 mm, craniocaudal motion increased by 6.9 ± 6.5 mm representing a 47 ± 36.5% and 14.5 ± 13.7% increase, respectively. The rotation of L1 about the mediolateral axis increased by 6.5° post-ISLD. Conclusion and Clinical Relevance: ISLD increases dorsoventral, craniocaudal, and rotational motion of the equine spine. The computer modeling methodology used here could be used to evaluate multiplanar spinal kinematics between treatments.

Erector spinae plane block as part of a multimodal analgesic approach in an anaesthetised horse undergoing dorsal spinous process ostectomy and desmotomy

AbstractA 14‐year‐old Irish sport horse presented to our institution with a history of right forelimb lameness and left‐sided back pain. Radiography and nuclear scintigraphy were performed under sedation and the horse was diagnosed with overriding dorsal spinous processes, also known as kissing spine syndrome. Surgical treatment consisted of dorsal spinous process ostectomy and desmotomy under general anaesthesia. This case report summarises the perianaesthetic management, which included an erector spinae plane block as part of a multimodal analgesic approach.

Morphological Investigations on Epistropheus in Ox and the Comparison of it with Resembling Bone in Horse, Dog, Sheep and Goat

Background: The documentation of anatomical features of epistropheus, which is also called as axis (C2) in different animals is not abundantly available on record. The observance of this C2 bone in ox made and compared it with the similar bone in different species of animals as to Horse, Dog, Sheep and Goat. The axis of ox was positioning cranially with spout like odontoid process which called as the dens. It was projected from the body. Due to its tooth like process, it was also known as vertebra dentata. The blade like supraspinous cranial process had increasing height and thickness towards its caudal progression, however, its infraspinous process was observed as the median ridge. While knowing such differential anatomical characters of axis (C2) in different species of animals as to Horse, Dog, Sheep and Goat this study is undertaken for comparison with the axis of Ox. Aims: Present endeavour aiming to have the comparative anatomical studies of the epistropheus i.e. axis (C2) bone of Ox and its comparison with the similar bone of Horse, Dog, Sheep and Goat. Materials and Methods: Six dried samples of second cervical of Ox (Bos indicus) were collected and explored its anatomical features. The comparative anatomical studies of the similar bone were performed in different species including horse (Equus ferus), dog (Canidae canis), sheep (Ovis aries) and goat (Capra hircus). Results: In horses, epistropheus i.e. axis the axis had longer body than the ox. The dens was conical and narrow. The axis of dog had cylindrical longer dens. Large and heightened spine as the pendant was observed, which was terminating caudally by the tuberosity of two crests. The axis of sheep had small, blunt and convex dorsal spinous process without remarkable ventral spine. The axis of goat had thin and heighted dorsal spinous process that overlaps the adjacent cranial and caudal cervical vertebrae. Conclusion: The findings of present studies are not only bringing the expositions of axis, the important bone of cervical region in different animals but also this is sufficiently bringing the fullest use for radiographic anatomy. KEY WORDS: Anatomy, Axis, Epistropheus, Ox, Horse, Dog, Sheep, Goat.

Supplementation of Screw-Rod C1-C2 Fixation With Posterior Arch Femoral Head Allograft Strut.

Numerous C1-C2 fixation techniques exist for the treatment of atlantoaxial instability. Limitations of screw-rod and sublaminar wiring techniques include C2 nerve root sacrifice and dural injury, respectively. We present a novel technique that utilizes a femoral head allograft cut with a keyhole that rests posteriorly on the arches of C1 and C2 and straddles the C2 spinous process, secured by sutures. To offer increased fusion across C1-C2 without the passage of sublaminar wiring or interarticular arthrodesis. A total of 6 patients with atlantoaxial instability underwent C1-C2 fixation using our method from 2015 to 2016. After placement of a C1-C2 screw/rod construct, a cadaveric frozen femoral head allograft was cut into a half-dome with a keyhole and placed over the already decorticated dorsal C1 arch and C2 spinous process. Notches were created in the graft and sutures were placed in the notches and around the rods to secure it firmly in place. The femoral head's shape allowed for creation of a graft that provides excellent surface area for fusion across C1-C2. There were no intraoperative complications, including dural tears. Postoperatively, no patients had sensorimotor deficits, pain, or occipital neuralgia. 5 patients demonstrated clinical resolution of symptoms by 3 mo and radiographic (computed tomography) evidence of fusion at 1 yr. One patient had good follow-up at 1 mo but died due to complications of Alzheimer disease. The posterior arch femoral head allograft strut technique with securing sutures is a viable option for supplementing screw-rod fixation in the treatment of complex atlantoaxial instability.

Equine Review

Introduction: This edition of Equine Review looks at the value of continuous per rectum fluid infusion, treatment of dorsal spinous process impingement by interspinous ligament desmotomy, and the use of radiographic monitoring to improve accuracy of needle placement into the distal intertarsal joint.

Are spinal deformities in ancient dogs related to weight bearing? The importance of fluctuating asymmetry

AbstractThe article “A howl from the grave: Osteological analysis of 12th‐ to 15th‐century dogs from Santa Ana, Manila, Philippines, International Journal of Osteoarchaeology, 2018” DOI:10.1002/oa.2644 discusses two vertebral abnormalities of ancient dogs: flattening of the tip and lateral deviation of the dorsal spinous process and considers possible causal use of dogs as beasts of burden. This idea also has been suggested in previous reports. We question this view and evaluate such spinal abnormalities in a modern veterinary context, using computerized tomography (CT)–scanned pet dogs that were not carrying weights or pulling travois or sledge. We show that identical asymmetries and anatomical variations occur in CT images of modern dogs that have not been carrying weights or pulling sledges or travois. We suggest that these features can be normal variants, expressing fluctuating asymmetry. We emphasize that health care settings provide the procedural mechanics and the means to evaluate and distinguish among diagnostic possibilities. We plead for increased collaboration among experienced veterinary specialists and zooarchaeologists when aberrations of ancient osteological structures are encountered. This cooperation will lead to more informed interpretations and avoid misdiagnosis and unrealistic lifestyle interpretations.

A new species of Echinolaophonte and record of E. armiger (Gurney, 1927) (Crustacea, Copepoda, Harpacticoida, Laophontidae) from the Caribbean with a key to species.

A new species of the harpacticoid copepod genus Echinolaophonte is described here from specimens obtained during a biological survey of Rodadero Bay, a coastal system in the Colombian Caribbean. This species has been previously recorded as E. armiger Gurney, 1927 in different geographic areas (Indian and Pacific Oceans). The Colombian specimens recognized as E. villabonae sp. n. and true E. armiger are deemed as distinct species based on differences in several features of which the shape of the rostrum and the dorsal spinous process on the prosome are among the most distinctive. These and other characters are shared by specimens recorded as E. armiger from Caroline Islands and Australia that are now incorporated to the new species. The finding of the true E. armiger, previously known only from Egypt, the Texan coast, Brazil, and possibly Bermuda, constitutes the first record of this species in the western Caribbean and a regional range extension. A key to the identification of the 13 known species of the genus is also provided.

Primer hallazgo de la familia Amathillopsidae Pirlot, 1934 (Crustacea, Amphipoda, Gammaridea), en el Mar Caribe, con la descripción de una especie nueva

A new species of the genus Amathillopsis is described. Main characteristics include the absence of eyes, accessory flagellum 1-segmented, distally emarginate telson, medial dorsal spinous process on pereionites 4-7, pleonites 1-3 and urosomite 1. This is the first record of a species of the family Amathillopsidae Pirlot, 1934 for the Caribbean Sea.

Solitary Osteochondroma Arising from the Dorsal Vertebral Spinous Process

Introduction: Osteochondroma are benign tumors which arise from aberrant cartilage nodules within the periosteum. They can be either pedunculated or sessile and are more common in the extremities and rarely seen in spine. En-bloc excision is the preferred treatment.&#x0D; Case Report: We present a case of 20 year female, who came with a swelling and pain in lower back for two years which was diagnosed to be thoracic vertebra(D11) osteochondroma on x-ray and computed tomography. Excision biopsy was done and confirmed it to be osteochondroma. There has been no recurrence even after 16 months of follow up.&#x0D; Conclusion: Although rare, osteochondroma of the vertebra should be kept in mind as a differential diagnosis when evaluating mass in spine. En bloc excision should be performed.

The Effect of Training on Stride Parameters in a Cohort of 40 Two Year Old Racehorses

IntroductionThe biomechanical effects of training on gait in the Thoroughbred are not fully understood. We aimed to assess the effect of training, surface and incline on stride parameters.Methods40 two‐year‐old Thoroughbred racehorses entering training were recruited and followed from December 2012 until September 2013. Gait analysis was performed at eleven time points by equipping each horse with an inertial measurement unit (IMU) with inbuilt GPS, mounted on the dorsum immediately caudal to the most caudal palpable lumbar dorsal spinous process. Horses were exercised as per their regular training regimen on a variety of training surfaces and inclines. Data were analysed using custom software written in Matlab (Mathworks, UK), and statistical analysis was performed using R (R Foundation for Statistical Computing, Austria). A linear mixed model was used, with horse as a random effect and weeks in training, training surface, curve and incline as fixed effects.ResultsA total of 85,497 strides at speeds of between 6.00 and 19.03 ms‐1 were analysed. Stride length increased by 0.33 m ± 4.3 x 104 with each 1 ms‐1 increase in velocity. Training causes a reduction in stride length of 0.004 ± 0.0001 m per week and an increase in stride frequency of 1.29 x 103 ± 4.1 x 105 per week. Shallow inclines, steep inclines and declines cause a decrease in stride length of 0.07 ± 0.003 m, 0.10 ± 0.005 m and 0.04 ± 0.004 m respectively. Turf and peat moss training surfaces caused an increase in stride length of 0.03 ± 0.004 m and 0.06 ± 0.007 m respectively.ConclusionsThis study provides an insight into the effects of external factors on the gait of young Thoroughbreds in training. Ongoing research will further investigate these effects and interactions.Ethical Animal ResearchThe study was approved by the local ethics committee. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Horserace Betting Levy Board. Competing interests: none.

Influence of head and neck position on radiographic measurement of intervertebral distances between thoracic dorsal spinous processes in clinically sound horses

Reductions in distances between dorsal spinous processes on radiographs are used as criteria for the diagnosis of impingement of the thoracic dorsal spinous processes in horses but are potentially altered by spine motion and different head and neck positions. To determine the influence of head and neck positions on intervertebral distances between dorsal spinous processes on radiographs of thoracic spines of clinically sound horses. Lateral-lateral radiographs were obtained from 23 horses in 3 head and neck positions. The width of the thoracic dorsal spinous processes and intervertebral distances between adjacent thoracic dorsal spinous processes were measured at points perpendicular to a tangent between the dorsal spinous processes and the caudal extremity of the thoracic vertebrae. A low head and neck position increased intervertebral distances between adjacent thoracic dorsal spinous processes from the 8th to 15th dorsal spinous processes whereas a high head and neck position had the opposite effect (P < 0.05). Overall, intervertebral distances between adjacent thoracic dorsal spinous processes decreased from cranial to caudal in intermediate head and neck positions (P < 0.01). The 12th thoracic dorsal spinous process was readily identifiable due to its significant difference to the narrower cranial and broader caudal dorsal spinous process (P < 0.05). The head and neck position influences the distances between the dorsal spinous processes of the vertebrae of equine thoracic spine on radiography. The measuring system reported here offers potential to improve and standardise radiographic evaluation of thoracic dorsal spinous processes.

Cervical Vertebral Stenosis Associated with a Vertebral Arch Anomaly in the Basset Hound

To report the clinical presentation, imaging characteristics, treatment results, and histopathological findings of a previously undescribed vertebral malformation in the Basset Hound. Retrospective case series study. Eighteen Basset Hounds presented for evaluation of a suspected cervical spinal cord problem. All dogs underwent computed tomography myelography or magnetic resonance imaging of the cervical region. Thirteen male and 5 female Basset Hounds between 6 months and 10.8 years of age (median: 1.4 years) were studied. Clinical signs varied from cervical hyperesthesia to nonambulatory tetraparesis. Imaging demonstrated a well-defined and smooth hypertrophy of the dorsal lamina and spinous process of ≥ 2 adjacent vertebrae. Although this bony abnormality could decrease the ventrodorsal vertebral canal diameter, dorsal midline spinal cord compression was predominantly caused by ligamentum flavum hypertrophy. The articulation between C4 and C5 was most commonly affected. Three dogs were lost to follow-up, 10 dogs underwent dorsal laminectomy, and medical management was initiated in 5 dogs. Surgery resulted in a good outcome with short hospitalization times (median: 4.5 days) in all dogs, whereas medical management produced more variable results. Histopathology confirmed ligamentum flavum hypertrophy and demonstrated the fibrocartilaginous nature of this anomaly. Dorsal lamina and spinous process hypertrophy leading to ligamentum flavum hypertrophy should be included in the differential diagnosis of Basset Hounds with cervical hyperesthesia or myelopathy. Prognosis after decompressive surgery is favorable. Although a genetic component is suspected, additional studies are needed to determine the specific etiology of this disorder.

Dorsal spinous process impingement syndrome (‘kissing spine’) in a cat: imaging appearance and surgical management

Spinal pain is an important clinical presentation in feline patients, but the underlying causes can often be difficult to elucidate. Dorsal spinous process impingement syndrome (‘kissing spine’ or in human patients ‘Baastrup syndrome’) is a significant cause of spinal pain in equine and human patients and radiographically is characterised by a close approximation of adjacent spinous processes with reactive bone sclerosis affecting these spinous processes. In this report we describe the first reported case of dorsal spinous process impingement syndrome in a cat causing spinal pain, and successful surgical management of the syndrome. The affected cat presented at 5 years of age for evaluation of a 7-month history of progressive thoracolumbar pain. Radiographs revealed close approximation of the dorsal spinous processes of the seventh, eighth and ninth thoracic vertebrae (T7, T8 and T9), with associated reactive bone sclerosis. Surgical resection of the T8 dorsal spinous process resulted in complete resolution of the clinical signs with no evidence of recurrence 9 months after surgery.

In this issue – October 2009

In this issue – October 2009

Stabilisation with dorsal and ventral fixation of a traumatic cervical instability in a dog

This case study reports the outcome of dorsal and ventral stabilisation of a traumatic cervical instability in a dog. A 2-year-old, male Pointer was admitted following a motor vehicle accident. Clinical examination revealed non-ambulatory tetraparesis, severe neck pain and upper motor neuron changes in all limbs. Deep pain response was present. Subluxation of C2/3 and fractures of the dorsal spinous process and lamina of C2 were observed on radiographs. Ventral stabilisation was performed with screws and bone cement (polymethylmethacrylate). For dorsal fixation of the fractures, screws and cerclage wire were used. The dog stood up independently after 1 month, was able to walk 1.5 months postoperatively and had recovered completely at 1 year following surgery. We conclude that combined stabilisation techniques are effective for this type of cervical fracture in which the dorsal, middle and ventral structures of the vertebra are severely disrupted.

The influence of body mass and thoracic dimensions on arterial oxygenation in anaesthetized horses and ponies

ObjectiveTo examine the relationship between body mass and thoracic dimensions on arterial oxygen tensions (PaO2) in anaesthetized horses and ponies positioned in dorsal recumbency. Study designProspective clinical study. AnimalsThirty six client-owned horses and ponies, mean [±SD (range)] age 8.1 ± 4.8 (1.5–20) years and mean body mass 467 ± 115 (203–656) kg. MethodsBefore general anaesthesia, food and water were withheld for 12 and 1 hours respectively. Body mass (kg), height at the withers (H), thoracic circumference (C), thoracic depth (length between dorsal spinous process and sternum; D), thoracic width (between point of shoulders; W), and thoracic diagonal length (point of shoulder to last rib; L) were measured. Pre-anaesthetic medication was with intravenous (IV) romifidine (0.1 mg kg−1). Anaesthesia was induced with an IV ketamine (2.2 mg kg−1) and diazepam (0.05 mg kg−1) combination and maintained with halothane in 1:1 oxygen:nitrous oxide (N2O) mixture. Animals were positioned in dorsal recumbency and allowed to breathe spontaneously. Nitrous oxide was discontinued after 10 minutes, and arterial blood samples obtained and analysed for gas tensions at 15, 30 and 60 minutes after connection to the anaesthetic breathing circuit. Data were analysed using anova and Pearson's correlation co-efficient. ResultsThe height per unit body mass (H kg−1) and thoracic circumference per unit body mass (C kg−1) correlated strongly (r = 0.85, p < 0.001 and r = 0.82, p < 0.001 respectively) with arterial oxygen tensions (PaO2) at 15 minutes. ConclusionsThere is a strong positive correlation between H kg−1 and C kg−1 and PaO2 after 15 minutes of anaesthesia in halothane-anaesthetized horses positioned in dorsal recumbency. Clinical relevanceReadily obtained linear measurements (height and thoracic circumference) and body mass may be used to predict the ability of horses to oxygenate during anaesthesia.

High-speed gallop locomotion in the Thoroughbred racehorse. II. The effect of incline on centre of mass movement and mechanical energy fluctuation

During locomotion on an incline, mechanical work is performed to move an animal up the slope and increase the potential energy (PE) of the trunk and hence the centre of mass (CoM). Thus, at a given speed the total net mechanical work increases with the PE of the animal. In this study we investigate the mechanical energy (ME) fluctuations and the mechanical cost of transport (MCT) in six horses galloping up a range of gradients. We captured trunk movement with a six degrees-of-freedom inertial sensor mounted over the dorsal spinous process of the fourth to sixth thoracic vertebrae of the horse. Footfall timings were measured using a previously validated system of limb-mounted accelerometers. Speed was measured using a Global Positioning System (GPS) data logger. A track survey provided detailed incline information for the track. Linear (craniocaudal, mediolateral and dorsoventral) and rotational (roll, pitch and heading) kinematic parameters (displacement, velocity and acceleration) were calculated at speeds ranging from 9.0 to 12.0 m s(-1) during routine training over a range of inclines. Estimates of ME fluctuations and the MCT were made. Results showed the effect of incline on trunk motion during galloping was small. Increases in linear mechanical work and MCT were primarily explained by an increase in the work required to move the animal up the slope (and increase the PE of the CoM). Within the stride the majority of the work was performed during hindlimb stance. Our results have provided new insights into how horses power uphill locomotion.