The effect of induced hindlimb lameness on thoracolumbar kinematics during treadmill locomotion

REASON FOR PERFORMING STUDY: There are no detailed studies describing a relationship between hindlimb lameness and altered motion of the back. OBJECTIVES: To quantify the effect of induced subtle hindlimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses were measured during walk and trot on a treadmill before and during application of pressure on the sole of the left hindlimb using a well-established sole pressure model. Reflective markers were located at anatomical landmarks on the limbs, back, head and neck for kinematic recordings. Ground reaction forces (GRF) in individual limbs were calculated from kinematics to detect changes in loading of the limbs. RESULTS: When pressure on the sole of the hindlimb was present, horses were judged as lame (grade 2 on the AAEP scale 1-5) by an experienced clinician. No significant unloading of this limb was found in the group of horses (unloading was observed in 4 animals, but was not detectable in the other 2), but statistically significant effects on back kinematics were detected. The overall flexion-extension (FE) range of motion (ROM) of the vertebral column was increased at walk, especially in the thoracic segments. Axial rotation (AR) ROM of the pelvis was also increased. At trot, the FE ROM was decreased only in the segment L3-L5-S3. During the stance phase of the lame limb, the segment T6-T10-T13 was more flexed and the neck was lowered at both gaits; the thoracolumbar segments were more extended at walk and trot. There were no significant changes in the stride length or protraction-retraction angles in any of the limbs. CONCLUSIONS: Subtle hindlimb lameness provoked slight but detectable changes in thoracolumbar kinematics. The subtle lameness induced in this study resulted in hyperextension and increased ROM of the thoracolumbar back, but also in decreased ROM of the lumbosacral segment and rotational motion changes of the pelvis. POTENTIAL RELEVANCE: Even subtle lameness can result in changes in back kinematics, which emphasises the intricate link between limb function and thoracolumbar motion. It may be surmised that, when chronically present, subtle lameness induces back dysfunction.     

Variation in free jumping technique within and among horses with little experience in show jumping

OBJECTIVE: To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among horses. ANIMALS: Fifteen 4-year-old Dutch Warmblood horses. PROCEDURE: The horses were raised under standardized conditions and trained in accordance with a fixed protocol for a short period. Subsequently, horses were analyzed kinematically during free jumping over a fence with a height of 1.05 m. RESULTS: Within-horse variation in all variables that quantified jumping technique was smaller than variation among horses. However, some horses had less variation than others. Height of the center of gravity (CG) at the apex of the jump ranged from 1.80 to 2.01 m among horses; this variation could be explained by the variation in vertical velocity of the CG at takeoff (r, 0.78). Horses that had higher vertical velocity at takeoff left the ground and landed again farther from the fence, had shorter push-off phases for the forelimbs and hind limbs, and generated greater vertical acceleration of the CG primarily during the hind limb push-off. However, all horses cleared the fence successfully, independent of jumping technique. CONCLUSIONS AND CLINICAL RELEVANCE: Each horse had its own jumping technique. Differences among techniques were characterized by variations in the vertical velocity of the CG at takeoff. It must be determined whether jumping performance later in life can be predicted from observing free jumps of young horses.     

Basic three-dimensional kinematics of the vertebral column of horses trotting on a treadmill

OBJECTIVE: To determine movements of the vertebral column of horses during normal locomotion. ANIMALS: 5 young Dutch Warmblood horses that did not have signs of back problems or lameness. PROCEDURE: Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Measurements were recorded when the horses were trotting on a treadmill at a constant speed of 4.0 m/s. RESULTS: Flexion-extension and axial rotation were characterized by a double sinusoidal pattern of motion during 1 stride cycle, whereas lateral bending was characterized by 1 peak and 1 trough. Ranges of motion for all vertebrae were: flexion-extension, 2.8 degrees to 4.9 degrees; lateral bending, 1.9 degrees to 3.6 degrees; axial rotation, 4.6 to 5.8 degrees, except for T10 and T13, where the amount of axial rotation decreased to 3.1 degrees and 3.3 degrees, respectively. CONCLUSION AND CLINICAL RELEVANCE: During locomotion, 3 types of rotations are evident in the thoracolumbar vertebrae. Regional differences are observed in the shape and timing of the rotations. These differences are related to actions of the limbs. The method described here for direct measurement of vertebral column motion provides insights into the complex movements of the thoracolumbar portion of the vertebral column in trotting horses. Information on normal kinematics is a prerequisite for a better understanding of abnormal function of the vertebral column in horses.     

ULTRASONOGRAPHIC TECHNIQUE AND NORMAL ANATOMIC FEATURES OF THE SACROILIAC REGION IN HORSES

The purpose of this study was to establish the normal percutaneous ultrasonographic appearance of anatomic structures within the equine sacroiliac region. Percutaneous ultrasonography was performed in a cranial-to-caudal direction in 10 normal adult live horses. The following structures were examined in detail: supraspinous ligament, lumbar and sacral spinous processes, thoracolumbar fascia and its caudal extension, tubera sacralia, ilial wings, dorsal and lateral portions of the dorsal sacroiliac ligaments, lateral part of the sacrum, and the lateral sacral crest. After ultrasonography, all animals were euthanized and detailed dissection of the lumbosacropelvic region was performed in six horses. Four lumbosacropelvic specimens were frozen and sectioned transversely for evaluation of cross-sectional anatomy. Gross anatomic findings were correlated with ante-mortem ultrasonographic images. On percutaneous ultrasonography, all horses had tubera sacralia with a mild-to-moderate roughened surface with occasional irregular hyperechoic mineralizations located within the apophyseal cartilage of younger horses. At the level of the tuber sacrale the caudal extension of the thoracolumbar fascia joined the dorsal portion of the dorsal sacroiliac ligament and assumed two different configurations relative to the dorsal portion of the dorsal sacroiliac ligament, with the predominant configuration of the thoracolumbar fascia located medial to the dorsal portion of the dorsal sacroiliac ligament. The less frequently encountered configuration had the thoracolumbar fascia positioned dorsal to the dorsal portion of the dorsal sacroiliac ligament. Caudal to the tuber sacrale the dorsal portion of the dorsal sacroiliac ligament and thoracolumbar fascia consolidated to form a single, fused structure with a common insertion on the sacral spinous processes. A large variability in linear fiber pattern, echogenicity (small focal hypoechoic areas), ligament height, and cross-sectional measurements was identified in the fused dorsal portion of the dorsal sacroiliac ligament and thoracolumbar fascia of normal horses. Diagnosing mild-to-moderate desmitis of the fused dorsal portion of the dorsal sacroiliac ligament and thoracolumbar fascia based solely on ultrasonography may therefore be difficult. To correlate ultrasonography with histology, samples of a fused dorsal portion of the dorsal sacroiliac ligament and thoracolumbar fascia with bilateral hypoechoic lesions were submitted for histology and revealed diffuse mild-to-moderate loss of fiber density, multifocal fibrocyte degeneration, and cartilagenous metaplasia with multifocal, mild myofiber mineralization, which was compatible with age-related changes. As controls, sections of ultrasonographically normal fused dorsal portion of the dorsal sacroiliac ligament and thoracolumbar fascia from three horses demonstrated similar but milder histologic findings, which were considered normal.     

The relationship between range of motion of lumbosacral flexion‐extension and canter velocity of horses on a treadmill

Reasons for performing study: Research into kinematics of the healthy equine back, has been performed in the walk and trot. This study focuses on back kinematics during canter, over a range of velocities. Flexion extension (FE) movements in canter are greatest in the lumbosacral (LS) region. Previous research has focused on canter velocity of 7 m/s; therefore quantification of LS kinematics at varying velocities is required to understand LS functions in equine locomotion. Hypothesis: Range of flexion‐extension movement through the lumbosacral joint increases with increasing velocity. Methods: Six Thoroughbred horses (mean age 9.6 years) cantered on treadmill at 4 velocities (6.0, 6.5, 7.0 and 8.0 m/s, respectively). Reflective markers were placed over the 5th lumbar vertebra (L5), the lumbosacral junction (LS) and the 3rd sacral vertebra (S3). Lumbosacral angle (LS) was defined as the angle formed between L5, LS and S3. Flexion‐extension (FE) range of motion (ROM) was analysed using a 2 camera, 3D motion capture system ProReflex¹. Linear regression was used to determine strengths of relationships between speed of canter and lumbosacral FE movements. Results: Range of FE ROM seen at the lumbosacral joint increased linearly with speed. FE ROM ranged 6.1°± 1.9 at 6 m/s, 6.3°± 1.9 at 6.5 m/s, 6.6°± 1.9 at 7 m/s and 7.2°± 1.9 at 8 m/s. Linear regression showed positive associations between speed and LS FE range of motion (r²= 0.993; P = 0.003). Conclusions and potential relevance: Results show linear relationships between LS FE movements and submaximal canter velocities. These results provide information on the LS joint at canter. Understanding the effects of velocity on the back of healthy horses may aid our understanding of the demands placed on this joint in sport horses at this gait.     

Identification of Equine Subclinical Lameness Induced by Pressure to the Sole of Fore- or Hindlimb

Lameness has been investigated in past studies with kinematic analyses, and the features of lameness have been qualitatively and quantitatively analyzed. The output was, however, limited to visible lameness that was scored by experienced clinicians. Subclinical supporting lameness that was induced by subtle pressure to the sole of limb, but that could not be detected by visual check, has yet to be extensively analyzed. To find specific kinematic parameters that were influenced by such subclinical lameness of the fore- or hindlimb, we produced subclinical, subtle and mild lameness in five sound horses by applying slight pressure to the sole. Trot on a treadmill was recorded by a high-speed camera. Symmetric properties of acceleration of the head and the tuber sacrale were disturbed in mild fore- and hindlimb lameness, respectively. In subclinical forelimb lameness, no obvious changes in the symmetric properties of the head, the withers, or the tuber sacrale were observed; however, the vertical lift-off acceleration of the treated forelimb was decreased. In the case of subclinical hindlimb lameness, the lift-off points of both the treated and sound hindlimb shifted posteriad. These findings may contribute to further investigations of subclinical lameness aiming to establish new procedures for early detection of subclinical musculoskeletal disease, which would enable more timely treatment.     

The sacroiliac joints: evaluation using nuclear scintigraphy. Part 2: Lame horses

REASONS FOR PERFORMING STUDY: Sacroiliac (SI) joint disease is difficult to diagnose definitively on clinical grounds. HYPOTHESES: Lameness not attributable to SI joint pain may result in asymmetrical uptake of radiopharmaceutical in the tubera sacrale and SI joints; and that horses with clinical signs suggestive of sacroiliac joint disease would have differences in the ratios of radiopharmaceutical uptake between the fifth lumbar vertebra (L5) and either the tubera sacrale or SI joints compared with normal horses. OBJECTIVES: To determine whether differences in radiopharmaceutical activity could identify individuals with presumed SI joint region pain. METHODS: The scintigraphic appearance of the pelvic region of 234 horses (Group I) with lameness unrelated to the SI joints was compared with that for 40 normal horses (Group N) in full work and that for 41 horses with suspected SI joint disease (Group II). The effect of age, sex, lame limb and discipline were assessed in Group I. Motion-corrected scintigraphic images were assessed grossly, using profile analysis and by comparing ratios of uptake of mean count per pixel between L5 and each of the left (L) tuber sacrale (TS), right (R) TS, LSI and RSI joints. Left-right symmetry was compared. RESULTS: Lame horses (Group I) had greater asymmetry of radiopharmaceutical uptake in the tubera sacrale compared with normal horses. Horses with right hindlimb lameness had a larger RSI/LSI ratio compared to normal horses. In Group I L5/LTS, L5/RTS and L5/RSI increased with age, and there was a trend for L5/LSI to increase with age. In horses with presumed sacroiliac joint disease (Group II), L5/LTS, L5/RTS and L5/RSI were all greater compared with normal horses. Detection of marked left-right asymmetry by quantitative analysis or profile analysis was helpful in discriminating between those horses with clinical signs compatible with SI joint disease and either normal horses or those lame due to another cause. CONCLUSIONS AND POTENTIAL RELEVANCE: Scintigraphic evaluation of the SI region is useful to identify SI joint disease in combination with other clinical signs supportive of the diagnosis. However, diagnosis should not be based on this alone because of some degree of overlap in the range of radiopharmaceutical uptake between horses with SI joint disease and both normal horses and those with other causes of lameness.     

A subjective descriptive study of the warm‐up and turn to a fence,approach, take‐off,suspension, landing and move‐off in 10 showjumpers

There is limited knowledge about causes of musculoskeletal injury in showjumpers. The objectives were to describe features of the turn, approach and jump in a group of experienced showjumpers believed by their riders to be sound, to relate these findings to clinical findings, and to identify features that may predispose to injury. Ten experienced showjumpers in normal competition training jumped an upright and a parallel fence four times off the left and right reins respectively, after a rider‐defined period of warm‐up. Real‐time and high‐speed motion capture was undertaken. Detailed subjective assessment of the gait was performed during the warm‐up, on the turn and approach to the jump and all phases of the jump. Six horses had thoracolumbar pain or epaxial muscle tension. Six horses exhibited a poor‐quality canter. The mean duration of warm‐up was 7 min (range 5–10 min). All horses had lean of the trunk and hindlimbs >45° on the turn. The inside hindlimb was placed in front of the outside hindlimb in 75% of the turns. Sideways oscillations of the hocks during stance were seen in all horses on the turn and on the straight approach in five horses. The inside hindlimb had greater magnitude of oscillation than the outside hindlimb on the turns. Repeated asynchronous push‐off with the hindlimbs at take‐off was seen in three horses. The hindlimbs drifted to the left or right during the ascent‐phase of suspension in four horses, reflecting asymmetrical push‐off. Only two horses landed consistently with the correct forelimb leading relative to the direction in which the horse had to turn after the fence. Four horses landed seven (n = 2) or eight (n = 2) times each with the left (n = 2) and right (n = 2) forelimbs respectively. Repetitive overload through asymmetrical use of the left and right canter leads, inadequate warm‐up, and limb instability could potentially predispose to injury.     

Variation in conformation of Swedish warmblood horses and conformational characteristics of élite sport horses

The variation in conformation of 356 Swedish Warmblood horses is described, using a quantitative method of measuring horses. Thirty-three of the horses were élite dressage horses, 28 were élite showjumpers, 100 were riding school horses and 195 were unselected four-year-olds. Most horses had a long body form. The average height at the withers was 163.4 cm. Sixty per cent of the horses had a bench knee conformation, 50 per cent had a toe-in conformation of the forelimbs and 80 per cent had outwardly rotated hind limbs. The majority of these deviations were mild or moderate. Conformation was influenced by sex and age. Mares were smaller and had longer bodies and shorter limbs. The élite dressage horses and showjumpers had larger hock angles and more sloping scapulas than other horses. The showjumpers also had smaller fetlock angles in the front limbs. It is suggested that the larger hock angles among the elite horses may be because hocks with small angles are more prone to injury, and because small hock angles may negatively influence the ability to attain the degree of collection necessary for good performance in advanced classes.     

The influence of head and neck position on kinematics of the back in riding horses at the walk and trot

REASONS FOR PERFORMING STUDY: A common opinion among riders and in the literature is that the positioning of the head and neck influences the back of the horse, but this has not yet been measured objectively. OBJECTIVES: To evaluate the effect of head and neck position on the kinematics of the back in riding horses. METHODS: Eight Warmblood riding horses in regular work were studied on a treadmill at walk and trot with the head and neck in 3 different predetermined positions achieved by side reins attached to the bit and to an anticast roller. The 3-dimensional movement of the thoracolumbar spine was measured from the position of skin-fixed markers recorded by infrared videocameras. RESULTS: Head and neck position influenced the movements of the back, especially at the walk. When the head was fixed in a high position at the walk, the flexion-extension movement and lateral bending of the lumbar back, as well as the axial rotation, were significantly reduced when compared to movements with the head free or in a low position. At walk, head and neck position also significantly influenced stride length, which was shortest with the head in a high position. At trot, the stride length was independent of head position. CONCLUSIONS: Restricting and restraining the position and movement of the head and neck alters the movement of the back and stride characteristics. With the head and neck in a high position stride length and flexion and extension of the caudal back were significantly reduced. POTENTIAL RELEVANCE: Use of side reins in training and rehabilitation programmes should be used with an understanding of the possible effects on the horse's back.     

A study on the techniques used by untrained horses during loose jumping

Deterministic models¹ developed for the jumping horseindicated the important factors involved when jumping an obstacle². SVHS video recordings were obtained of 31 untrained horses (age: 3–5 years, height: 164.7±4.5 cm) jumping loose over a fence 1 m high by 0.5 m wide. The horses were designated to either a good group or a poor group based on a qualitative evaluation; good horses (n=18) cleared the fence with ease, and poor horses (n=13) consistently hit the fence. Video sequences were digitized to provide kinematic data on the horses' center of gravity (CG) and carpal and tarsal angles. Twenty kinematic variables were examined from the approach to the landing. Analysis of Variance (ANOVA) revealed significant between-group differences for the horizontal velocity of the last approach stride (Good: 5.77±0.80 m.s⁻¹; Poor: 6.42±0.95 m.s⁻¹; p=0.046). Significant differences were found in the relative carpal angles at take off (Leading limb: Good: 1.02±0.19 rad, Poor: 1.25±0.28 rad; p=0.010; Trailing limb: Good: 0.92±0.21 rad, Poor: 1.06±0.15 rad; p=0.046). The height of the CG over the center of the fence was also a significant variable that differed between the groups (Good: 1.83±0.08 m; Poor: 1.71±0.13 m; p=0.002). Finally the horizontal velocity of the landing was significant (Good: 5.26±0.92 m.s⁻¹; Poor: 6.27±0.84 m.s⁻¹; p=0.004) along with the angle of the CG to the ground at landing (Good: −0.45±0.08 rad; Poor: −0.38±0.07 rad). The velocity and CG variables which distinguished good and poor horses are likely to be strongly influenced by a rider; therefore, it is unlikely that these data alone could be used to predict elite jumping horses. The carpal angle data, however, may indicate a certain natural tendency by the young horses in the good group to keep their legs clear of the fence.     

The effect of fence height and width on the limb placements of show jumping horses

The purpose of the study was to investigate the effect of fence type (vertical, square oxer) and fence height (1.10 m, 1.25 m, 1.40 m) on the limb displacements from the base of the fence during the approach, take off, landing and move off. Four experienced Grand Prix jumpers were filmed using 2 high speed 16 mm cine cameras set up in series, perpendicular to the path of jumping motion. A minimum of 8 limb impacts on each side of the fence were recorded during a total of 96 jumping efforts. The variables measured were fence type, fence height, total distance jumped, and the limb displacements from the fence. The limb displacements were measured from the base of the first element on the take- off side and from the base of the last element on the landing side. A repeated-measures desing, multivariate analysis of variance was used to determine the effect of fence type and fence height on the displacement of the limbs from the fence and on the total jump distance. A conservative value of 0.01 alpha was used to minimize the likelihood of falsely classifying an effect as significant.There was no interaction between the effects of fence type and fence height for any of the variables. The positions of the limb placements on the take-off side of the fence were independent of both type and height. On the landing side the placements of the lead forelimb at landing and the lead hind limb in the first stride after landing were closer to the last element of the oxer than the vertical at all heights (P<.01). Fence height had a significant effect on the displacement from the base of the last element for both forelimbs at landing, and for the trailing hind limb and both forelimbs in the subsequent stride (P<.01). Duncan's multiple comparison test indicated that there was a progressive increase in the displacement of these 5 limbs from the last element as the height of the fence increased. The jump distance was independent of fence type, but was shown to increase significantly with fence height (P<.01). The results have implications for course designers in setting the distances between fences and for riders in anticipating the effects of these distances.     

Reducing Peak Pressures Under the Saddle Panel at the Level of the 10th to 13th Thoracic Vertebrae May Be Associated With Improved Gait Features,Even When Saddles Are Fitted to Published Guidelines

Saddle–horse interaction is increasingly linked with back pain, performance, and welfare issues. Saddle fit and work quality influence alterations in back shape with exercise at thoracic vertebra 13 level (T13) with exercise. The objectives of experiments were to: determine a repeatable zone and stride point of peak pressure under saddles fitted to industry guidelines; compare peak pressure in this zone and limb kinematics in collected trot between horses own saddles (S) and a saddle designed to reduce pressure at T10–T13 (F); compare thoracolumbar width change after exercise between S and F and with F after 3 months use. Elite dressage (n = 13) horses/riders with no lameness/performance problem had pressure mat data acquired under S, fitted by four qualified saddle fitters, to determine zones of peak pressure. Pressure mat data at T10–T13, forelimb/hindlimb protraction, and carpal/tarsal flexion acquired using simultaneous high-speed motion capture, and difference in thoracolumbar dimensions (T8, T18 at 3, 15 cm) between before and after exercise was compared between S and F. Peak pressures were consistently detected axially around T10–T13 (sensors A4–A7, H4–H7). Peak pressures were significantly less with F than S for each cell and pooled (55%–68% difference. P = .01 to <.0001). Saddle F was associated with 13% greater forelimb and 22.7% hindlimb protraction, 3.5° greater carpal and 4.3° tarsal flexion (P = .02 to .0001), and greater increase in thoracolumbar dimensions after exercise (P = .01 to <.0001). Saddles fitted to published guidelines may still have a nonideal interface with horses. Reducing peak pressures around T10–T13 was associated with improved limb kinematics in trot and greater thoracolumbar expansion after exercise.     

Changes in walking parameters of milking cows after hoof trimming

We examined the walking parameters of milking cows in relation to hoof trimming. The hooves of eight Holstein cows were trimmed. Two days before and after the hoof trimming, walking behavior, limb angles, back posture and vertical movement of the back while walking were measured. Walking rate (1.27 vs 0.87 m/s; P = 0.003), step length (1.46 vs 1.33 m; P = 0.009) and stepping rate (0.78 vs 0.65 steps/s; P = 0.046) were found to increase significantly after hoof trimming. Limb angles at the start and end of the support phase changed significantly after hoof trimming, thus indicating an improvement in the ‘on tiptoe’ appearance. The parameters relating to backline indicated that the marked arched shape of the back diminished after hoof trimming. Before hoof trimming, the positions of the withers varied widely and irregularly while walking; however, it changed after hoof trimming as the sinusoid curve and the range of vertical movement of withers decreased significantly. Overall, it has been quantitatively indicated that walking characteristics are improved after hoof trimming. The parameters used in the present study are expected to be useful for monitoring the walking characteristics of cows.     

青年伊犁马步幅指数及步频指数与运动性能的关联性分析

试验旨在研究青年伊犁马不同运动性能间步幅指数与步频指数的差异,并探究其与运动性能的关联性,以期提高伊犁马个体选择和性能测定的科学性和准确性。试验以参加伊犁马常态化赛事的72匹2岁伊犁马为研究对象,测量其体尺与步态特征,计算其各项步幅指数与步频指数,分析不同途程、不同运动性能间的差异,并对各指标与竞赛用时做偏相关分析,探究各指标与运动性能的关联性。结果表明,伊犁马1 600 m竞赛中,精英组体高步频指数、体长步频指数均极显著高于普通组（P<0.01）,且与竞赛用时呈极显著负相关（P<0.01）,精英组体高双支撑相步幅指数、体长双支撑相步幅指数、体高步幅指数、体长步幅指数均极显著高于普通组（P<0.01）,并与竞赛用时呈极显著负相关（P<0.01）;3 600 m竞赛中,精英组体高步频指数、体长步频指数极显著高于普通组（P<0.01）,体长步频指数与竞赛用时呈极显著负相关（P<0.01）,精英组体高双支撑相步幅指数,体长双支撑相步幅指数均显著高于普通组（P<0.05）,且与竞赛用时呈显著负相关（P<0.05）。体高步频指数与体长步频指数可作为青年伊犁马的首选性能评估和选择指标,可广泛用于青年伊犁马育种和训练实践中,以提高性能评估效率。     

Basic three-dimensional kinematics of the vertebral column of horses walking on a treadmill

OBJECTIVE: To determine kinematic movements of the vertebral column of horses during normal locomotion. ANIMALS: 5 Dutch Warmblood horses without apparent lameness or problems associated with the vertebral column. PROCEDURE: Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Horses were recorded while walking on a treadmill at a constant speed of 1.6 m/s. RESULTS: Flexion-extension was characterized by 2 periods of extension and flexion during 1 stride cycle, whereas lateral bending and axial rotation were characterized by 1 peak and 1 trough. The range of motion for flexion-extension was fairly constant for vertebrae caudal to T10 (approximately 7 degrees). For lateral bending, the cranial thoracic vertebrae and segments in the pelvic region had the maximal amount of motion, with values of up to 5.6 degrees. For vertebrae between T17 and L5, the amount of lateral bending decreased to <4 degrees The amount of axial rotation increased gradually from 4 degrees for T6 to 13 degrees for the tuber coxae. CONCLUSIONS: This direct measurement method provides 3-dimensional kinematic data for flexion-extension, lateral bending, and axial rotation of the thoracolumbar portion of the vertebral column of horses walking on a treadmill. Regional differences were observed in the magnitude and pattern of the rotations. Understanding of the normal kinematics of the vertebral column in healthy horses is a prerequisite for a better understanding of abnormal function.     

Pain associated with the sacroiliac joint region: a clinical study of 74 horses

REASONS FOR PERFORMING STUDY: There has been no large study of horses with suspected sacroiliac (SI) joint region pain in which the clinical diagnosis has been supported by either abnormal radiopharmaceutical activity in the SI joint region or by periarticular infiltration of local anaesthetic solution. OBJECTIVES: To describe the clinical features of horses with SI joint region pain, to document the age, breed, sex, discipline, size and conformation of affected horses and to compare these with the author's (SD) normal case population and to document the results of infiltration of local anaesthetic solution around the SI joint region. METHODS: Horses were selected for inclusion in the study based upon the exclusion of other causes of lameness or poor performance, together with clinical signs suggestive of SI joint pain and abnormal radiopharmaceutical activity in the SI joint region and/or a positive response to periarticular infiltration of local anaesthetic solution. RESULTS: Sacroiliac joint region disease was identified in 74 horses between November 1997 and March 2002. Dressage and showjumping horses appeared to be at particular risk (P < 0.001). Affected horses were generally slightly older than the normal clinic population (P < 0.0001), taller at the withers (P < 0.0001) and of greater bodyweight (P < 0.01). There was a significant effect of breed (P < 0.001), with a substantially higher proportion of Warmblood horses (51%) in the SI pain group compared to the normal clinic population (29%). There was no correlation between conformation and the presence of SI joint region pain. The tubera sacrale appeared grossly symmetrical in most (95%) horses. Poor development of the epaxial muscles in the thoracolumbar region and asymmetry of the hindquarter musculature were common. Twenty-six horses (35%) showed restricted flexibility of the thoracolumbar region and 10 (16%) had an exaggerated response to pressure applied over the tubera sacrale. Fourteen horses (19%) were reluctant to stand on one hindlimb for prolonged periods. The majority of horses (75%) had a straight hindlimb flight and only 18% moved closely behind or plaited. In all horses restricted hindlimb impulsion was the predominant feature; invariably this was most obvious when the horse was ridden. Stiffness, unwillingness to work on the bit and poor quality canter were common. Sacroiliac joint region pain was seen alone (47%), or in conjunction with thoracolumbar pain (16%), hindlimb lameness (20%), forelimb lameness (7%) or a combination of problems (10%). Seventy-three horses (99%) had abnormalities of the SI joint region identified using nuclear scintigraphy. Infiltration of local anaesthetic solution around the SI joint region produced profound improvement in gait in all 34 horses in which it was performed. CONCLUSIONS AND POTENTIAL RELEVANCE: Careful clinical examination combined with scintigraphic evaluation of the SI joint region and local analgesia can enable a more definitive diagnosis of SI joint region pain than has previously been possible.     

The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion

REASONS FOR PERFORMING STUDY: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. OBJECTIVES: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. RESULTS: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2 degrees at walk and increased by 3.3 degrees at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9 degrees at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7degrees at T13, 0.8 degres at T17, 0.5 degres at L1, 0.4 degrees at L3 and 0.3 degrees at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3 degrees at T10 and 0.9 degrees at T13) (P<0.05) during stance of the lame diagonal. CONCLUSIONS: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. POTENTIAL RELEVANCE: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness.     

Use of high-speed cinematography and computer generated gait diagrams for the study of equine hindlimb kinematics

High-speed cinematography with computer aided analysis was used to study equine hindlimb kinematics. Eight horses were filmed at the trot or the pace. Filming was done from the side (lateral) and the back (caudal). Parameters measured from the lateral filming included the heights of the tuber coxae and tailhead, protraction and retraction of the hoof and angular changes of the tarsus and stifle. Abduction and adduction of the limb and tarsal height changes were measured from the caudal filming. The maximum and minimum values plus the standard deviations and coefficients of variations are presented in tabular form. Three gait diagrams were constructed to represent stifle angle versus tarsal angle, metatarsophalangeal height versus protraction-retraction (fetlock height diagram) and tuber coxae and tailhead height versus stride (pelvic height diagram). Application of the technique to the group of horses revealed good repeatability of the gait diagrams within a limb and the diagrams appeared to be sensitive indicators of left/right asymmetries.