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.     

A Randomized Blinded Crossover Clinical Trial to Determine the Effect of an Oral Joint Supplement on Equine Limb Kinematics,Orthopedic, Physiotherapy,and Handler Evaluation Scores

Despite the range of oral joint supplements available, there has been very limited research into their efficacy. The study aimed to determine the effect of an oral joint supplement on limb kinematics, orthopedic, physiotherapy, and handler evaluation in horses. Supplement S or placebo P was fed to 24 horses for 21 days each in a random order. Horses were evaluated at days 0 (baseline), 21 (after first treatment), and 42 (after second treatment). Assessments included the following: clinical orthopedic evaluation for straight line/lunging circle in walk and trot; high-speed motion capture determined hindlimb kinematics for straight-line trotting; grading of limb range of motion (ROM) and muscle tone based on standardized physiotherapy criteria; handler grading of specific criteria during pasture, groundwork, and ridden exercise. Effect of treatment, sequence, limb, and interactions were investigated using linear-mixed models. S was associated with significantly lower lameness grade in a straight line (P = .001) and circle (P = .010), with individual horses improving up to 2/10 grades over P/baseline. S was associated with significantly improved ROM and muscle tone. Ridden/groundwork scores were significantly higher with S compared to P/baseline. With S, horses were graded significantly higher for “ease of movement” at pasture compared with P/baseline. For horses with hindlimb lameness, S was associated with significantly greater tarsal flexion than baseline (4.2% greater, P < .020) or P (2.7% greater, P < .037). S was associated with less lameness and improved physiotherapy scores, ridden/groundwork scores, and pasture “ease of movement.” Increased midstance tarsal flexion of lame limbs may indicate improved mobility/comfort during peak loading, supporting a positive effect of S.     

Effect of chiropractic manipulations on the kinematics of back and limbs in horses with clinically diagnosed back problems

REASON FOR PERFORMING STUDY: Although there is anecdotal evidence of clinical effectiveness of chiropractic in treatment of equine back pain, little scientific work has been reported on the subject. OBJECTIVES: To quantify the effect of chiropractic manipulations on back and limb kinematics in horse locomotion. METHODS: Kinematics of 10 Warmblood horses were measured over ground at walk and trot at their own, preferred speed before, and one hour and 3 weeks after chiropractic treatment that consisted of manipulations of the back, neck and pelvic area. Speed was the same during all measurements for each horse. RESULTS: Chiropractic manipulations resulted in increased flexion-extension range of motion (ROM) (P<0.05) at trot in the vertebral angular segments: T10-T13-T17 (0.3 degrees ) and T13-T17-L1 (0.8 degrees ) one hour after treatment, but decreased ROM after 3 weeks. The angular motion patterns (AMPs) of the same segments showed increased flexion at both gaits one hour after treatment (both angles 0.2 degrees at walk and 0.3 degrees at trot, P<0.05) and 3 weeks after treatment (1.0 degrees and 2.4 degrees at walk and 1.9 degrees and 2.9 degrees at trot, P<0.05). The lumbar (L3 and L5) area showed increased flexion after one hour (both angles 0.3 degrees at walk and 0.4 degrees at trot P<0.05), but increased extension after 3 weeks (1.4 degrees and 1.2 degrees , at trot only, P<0.05). There were no detectable changes in lateral bending AMPs. The inclination of the pelvis was reduced at trot one hour (1.6 degrees ) and 3 weeks (3 degrees ) after treatment (P<0.05). The mean axial rotation of the pelvis was more symmetrical 3 weeks after the treatment at both gaits (P<0.05). There were no changes in limb angles at walk and almost no changes at trot. CONCLUSIONS: The main overall effect of the chiropractic manipulations was a less extended thoracic back, a reduced inclination of the pelvis and improvement of the symmetry of the pelvic motion pattern. POTENTIAL RELEVANCE: Chiropractic manipulations elicit slight but significant changes in thoracolumbar and pelvic kinematics. Some of the changes are likely to be beneficial, but clinical trials with increased numbers of horses and longer follow-up are needed.     

Effect of induced unilateral synovitis of distal intertarsal and tarsometatarsal joints on sagittal plane kinematics and kinetics of trotting horses

OBJECTIVE: To study the effect of unilateral synovitis in the distal intertarsal and tarsometatarsal joints on locomotion, including the compensating effects within and between limbs. ANIMALS: 4 clinically normal horses. PROCEDURE: Gait analyses including kinematics, force plate, and inverse dynamic analysis were performed at the trot before lameness, after which synovitis was induced by injecting endotoxin into the right distal intertarsal and tarsometatarsal joints. Gait analyses were repeated 24 to 30 hours later during lameness. Differences between the stride variables during the 2 conditions (lame and sound) were identified. RESULTS: Tarsal joint range of motion, peak vertical force, and vertical impulse were decreased during lameness. Mechanical deficits included a decrease in negative work performed by the tarsal extensors during the early stance phase and a decrease in positive work by the tarsal extensors during push off. No compensatory changes in work were performed by other joints within the lame hind limb during the stance phase. Vertical impulse in the diagonal forelimb decreased, but there were no significant changes in forces or impulses in the ipsilateral forelimb or contralateral hind limb. CONCLUSION AND CLINICAL RELEVANCE: Results indicate that horses are able to manage mild, unilateral hind limb lameness by reducing the airborne phase of the stride rather than by increased loading of the compensating limbs.     

Crooked tail carriage in horses: Increased prevalence in lame horses and those with thoracolumbar epaxial muscle tension or sacroiliac joint region pain

The relationship between lameness and crooked tail carriage (CTC) in horses is unclear. The objectives of this study were (i) to determine the association between CTC and lameness; (ii) among lame horses, to determine associations between CTC and lameness diagnosis, saddle slip, thoracolumbar range of motion (ROM), epaxial muscle tension and pain, and sacroiliac joint region (SIJR) pain, and (iii) to determine whether abolition of lameness and SIJR pain by diagnostic anaesthesia modified CTC. In this study, 520 lame and 170 nonlame sports horses were examined for CTC and other characteristics by one clinician (S.J.D.). All horses were evaluated when ridden. Lame horses were also assessed in hand and on the lunge. Crooked tail carriage, its direction, lameness, musculoskeletal and tack-related parameters were recorded as binary variables and analysed using 2 × 2 contingency tables. Sacroiliac joint region pain was diagnosed using local anaesthesia. Standard errors are shown in square brackets. 32.5% of lame horses had CTC, compared with 5.3% of nonlame horses (odds ratio = 8.6 [confidence intervals 4.4, 16.7]; P = 2×10⁻¹²). Of 169 lame horses with CTC, 103 (60.9% [3.8%]) held their tail to the left. There was no association between the side of the predominant lame limb and CTC direction. However, CTC was more common (P = 0.005) in horses with hindlimb lameness (35.7% [2.4%], N = 401) compared with forelimb lameness (21.0% [4.1%], N = 100). Crooked tail carriage was associated with SIJR pain (P = 0.0007) and thoracolumbar epaxial muscle tension (P = 0.0007), but not with saddle slip, reduced thoracolumbar ROM or thoracolumbar epaxial muscle pain. Limitations of the study included the facts that nonlame horses were a convenience sample and lameness assessment, other clinical observations and determination of the presence of CTC were subjective, with potential for bias. Video recordings and photographs are available for verification of tail position. It was concluded that CTC is more prevalent in lame horses than nonlame horses. There is a positive association between CTC and hindlimb lameness, SIJR pain and thoracolumbar epaxial muscle tension.     

Compensatory load redistribution of horses with induced weightbearing hindlimb lameness trotting on a treadmill

REASONS FOR PERFORMING STUDY: The compensatory mechanisms of horses with weightbearing hindlimb lameness are still not fully understood. HYPOTHESIS: That weightbearing, unilateral hindlimb lameness would not only alter stride characteristics to diminish structural stress in the affected limb but also induce compensatory load adjustments in the other supporting limbs. OBJECTIVE: To document the load and time shifting mechanisms of horses with unilateral weightbearing hindlimb lameness. METHODS: Reversible lameness was induced in 8 clinically sound horses by applying a solar pressure model. Three degrees of lameness (subtle, mild and moderate) were induced and compared with the nonlame (sound) control measurement. Vertical ground reaction forces were recorded for all 4 limbs simultaneously on an instrumented treadmill. RESULTS: Compared to the sound situation, moderate hindlimb hoof lameness induced a decrease in stride duration (-3.3%) and stride impulse (-3.1%). Diagonal impulse decreased selectively in the lame diagonal stance (-7.7%). Within the diagonal limb pair, vertical impulse was shifted to the forelimb during the lame diagonal stance (+6.5%) and to the hindlimb during the sound diagonal stance (+3.2%). Peak vertical force and vertical impulse decreased in the lame limb (-15%), but only vertical impulse increased in the contralateral hindlimb (+5.7%). Stance duration was prolonged in both hindlimbs (+2.5%). Suspension duration was reduced to a greater extent after push-off of the lame diagonal limb pair (-21%) than after the sound diagonal limb pair (-9.2%). CONCLUSIONS: Four compensatory mechanisms could be identified that served to reduce structural stress, i.e. peak vertical force on the affected limb: 1) reduction of the total vertical impulse per stride; 2) diagonal impulse decreased selectively in the lame diagonal; 3) impulse was shifted within the lame diagonal to the forelimb and in the sound diagonal to the hindlimb; and 4) the rate of loading and peak forces were reduced by prolonging the stance duration. POTENTIAL RELEVANCE: Load shifting mechanisms are not only effective in diminishing peak forces in the affected limb, but also suppress compensatory overload in other limbs. Selected force and time parameters allow the unequivocal identification of the lame limb. Future studies have to examine how far these compensatory mechanisms may be generalised for other defined orthopaedic problems in the hindlimb.     

Effect of local analgesia on movement of the equine back

REASONS FOR PERFORMING STUDY: Diagnostic infiltration of local anaesthetic solution is commonly used in cases of equine back pain. Evaluation is subjective and it is not known how local analgesia of the back affects horses without clinical signs of back pain. OBJECTIVES: To evaluate the effect of infiltration of local anaesthetics on the movement of the back in horses without clinical signs of back pain, and to evaluate the usefulness of kinematic studies as an objective and quantitative tool in evaluating local analgesia in clinical practice. METHODS: The kinematics of the back in 10 clinically sound horses were measured on 2 occasions at walk and trot before and after injections with mepivacaine and sodium chloride around the interspinous spaces between T16 and L2. The kinematics were compared between the 2 occasions before injections and before and after each injection. RESULTS: The range of motion (ROM) for dorsoventral flexion-extension (FE) of the back was increased significantly in all measured segments other than T10 at walk, as was lateral bending (LB) at T10, L3 and L5 after injection of mepivacaine. For lateral excursion (LE), total movement increased at all measured segments. At trot the only affected segment was L3, where the injection with mepivacaine decreased the ROM for FE. After injection of sodium chloride the ROM for FE increased at T13 and T17 at walk. Lateral bending and LE were not affected at walk. At trot, LB increased at L3 and L5. CONCLUSIONS AND POTENTIAL RELEVANCE: Diagnostic infiltration of local anaesthetic solution affects the function of the back in clinically sound horses, which must be considered when interpreting the use of this clinical aid in assessing clinical cases of back dysfunction. Kinematics can qualitatively and quantitatively evaluate the effect of local analgesia of the back.     

Repeatability of subjective evaluation of lameness in horses

Reasons for performing study: Previous studies have suggested that agreement between equine veterinarians subjectively evaluating lameness in horses is low. These studies were limited to small numbers of horses, evaluating movement on the treadmill or to evaluating previously‐recorded videotape. Objectives: To estimate agreement between equine practitioners performing lameness evaluations in horses in the live, over ground setting. Methods: 131 mature horses were evaluated for lameness by 2–5 clinicians (mean 3.2) with a weighted‐average of 18.7 years of experience. Clinicians graded each limb using the AAEP lameness scale by first watching the horse trot in a straight line only and then after full lameness evaluation. Agreement was estimated by calculation of Fleiss' (κ). Evaluators agreed if they picked the same limb as lame or not lame regardless of the severity of perceived lameness. Results: After only evaluating the horse trot in a straight line clinicians agreed whether a limb was lame or not 76.6% of the time (κ= 0.44). After full lameness evaluation clinicians agreed whether a limb was lame or not 72.9% of the time (κ= 0.45). Agreement on forelimb lameness was slightly higher than on hindlimb lameness. When the mean AAEP lameness score was >1.5 clinicians agreed whether or not a limb was lame 93.1% of the time (κ= 0.86), but when the mean score was ≤1.5 they agreed 61.9% (κ= 0.23) of the time. When given the task of picking whether or not the horse was lame and picking the worst limb after full lameness evaluation, clinicians agreed 51.6% (κ= 0.37) of the time. Conclusions: For horses with mild lameness subjective evaluation of lameness is not very reliable. Potential relevance: A search for and the development of more objective and reliable methods of lameness evaluation is justified and should be encouraged and supported.     

Compensatory load redistribution of horses with induced weight-bearing forelimb lameness trotting on a treadmill

The study was performed to obtain a detailed insight into the load and time shifting mechanisms of horses with unilateral weight-bearing forelimb lameness. Reversible lameness was induced in 11 clinically sound horses by applying a solar pressure model. Three degrees of lameness (subtle, mild and moderate) were induced and compared with sound control measurements. Vertical ground reaction force-time histories of all four limbs were recorded simultaneously on an instrumented treadmill. Four compensatory mechanisms could be identified that served to reduce structural stress, i.e. peak vertical force on the affected limb: (1) with increasing lameness, horses reduced the total vertical impulse per stride; (2) the diagonal impulse decreased selectively in the lame diagonal; (3) the impulse was shifted within the lame diagonal to the hindlimb and in the sound diagonal to the forelimb; (4) the rate of loading and the peak forces were reduced by prolonging the stance duration. Except in the diagonal hindlimb, where peak vertical forces increased slightly in the moderate lameness condition, no equivalent compensatory overload situation was observed in the other limbs. Specific force and time information of all four limbs allow the unequivocal identification of the affected limb.     

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.     

Proximal hindlimb flexion in the horse: Effect on movement symmetry and implications for defining soundness

Reasons for performing the study: Flexion tests are a common tool during the prepurchase and clinical lameness examination, yet studies quantifying the effect of flexion, apart from distal forelimb flexion in sound horses, are sparse. Objectives: To investigate the effect of proximal hindlimb flexion on perceivable and measurable changes in movement symmetry in horses with objective movement symmetry falling within the margins of ‘sound’. Methods: Thirteen horses, selected based on objective movement symmetry, were instrumented with inertial sensors on left and right tuber coxae and over the os sacrum. Vertical movement symmetry was quantified at trot before and after proximal hindlimb flexion, with a repeat of flexion after 5 min. Video recordings of the horses were assessed visually. Results: Proximal hindlimb flexion introduced additive changes in movement symmetry to the individual baseline movement, with a tendency towards smaller effects with increasing stride number. The main systematic effect was a decrease in upward movement of the os sacrum following mid‐stance of the flexed limb and an increase in upward movement following mid‐stance of the nonflexed limb, also manifesting in a ‘hip hike’ of the flexed limb; these findings reflected increased movement asymmetry following flexion. Depending on individual baseline asymmetry, flexion can also increase movement symmetry. Conclusions: Proximal hindlimb flexion can exacerbate subtle asymmetry when performed carefully. Variation in measured symmetry following flexion within and between horses showed that the individual response to flexion is highly variable. Potential relevance: Proximal hindlimb flexion may elevate the asymmetry of a slightly lame limb above the threshold for visibility, thus assisting in the clinical gait examination. Further work is needed to examine the causes for a positive response to flexion and possible differences between sound and lame horses as well as horses of different athletic disciplines.     

A Quantitative Review of the Equinalysis System for Equine Locomotion Analysis

Movement analysis techniques allow objective and quantitative assessment of kinematic gait analysis. Consistent repeatability of the kinematic data is essential for such assessments. This study investigated whether the repeatability of a standardized Equinalysis Elite gait analysis system is sufficient to allow its use in clinical evaluation of equine lameness with reliable documentation of individual locomotion patterns. The extent to which examinations on different days affected the results when a standardized protocol was used was investigated. The repeatability of distal limb kinematics in nine sound horses over three successive days at one location was investigated. Measurements were performed at the examination area, for three motion cycles at the walk and trot, in each direction per day. Skin markers were placed on the lateral aspect of the coffin joint, forelimb fetlock joint, hindlimb fetlock joint, carpus, tarsus, elbow, and stifle, at clipped sites marked with a permanent marker. The inter-day repeatability of angular measurements of the carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints was determined. A low degree of inter-day repeatability was found with statistically significant (P ≤ .05) differences between findings on different days, observed in the time-angle diagrams of left and right carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints of all horses, at both walk and trot. The standardized Equinalysis Elite system for gait analysis of distal limb kinematics in the horse did not provide highly repeatable data in this setting.     

Kinematic evaluation of the back in the sport horse with back pain

REASONS FOR PERFORMING STUDY: Earlier studies have developed a clinical tool to evaluate objectively the function of the equine back. The ability to differentiate horses with back pain from asymptomatic, fully functioning horses using kinematic measures from this tool has not been evaluated. OBJECTIVES: To compare the kinematics of the back at walk and trot in riding horses with back dysfunction to the same parameters in asymptomatic sport horses. METHODS: The kinematics of the back in 12 horses with impaired performance and back pain were studied at walk and trot on a treadmill. Data were captured for 10 sees at 240 Hz. Range of movement (ROM) and intravertebral pattern symmetry of movement for flexion and extension (FE), lateral bending (LB) and axial rotation (AR) were derived from angular motion pattern data and the results compared to an earlier established database on asymptomatic riding horses. RESULTS: At walk, horses with back dysfunction had a ROM smaller for dorsoventral FE in the caudal thoracic region (T13 = 7.50 degrees, T17 = 7.71 degrees; P<0.05), greater for LB at T13 (8.13 degrees; P<0.001) and smaller for AR of the pelvis (10.97 degrees; P<0.05) compared to asymptomatic horses (FE-T13 = 8.28 degrees, FE-T17 = 8.49 degrees, LB-T13 = 6.34 degrees, AR-pelvis = 12.77 degrees). At trot, dysfunctional horses had a smaller (P<0.05) ROM for FE at the thoracic lumbar junction (T17 = 2.46 degrees, L1 = 2.60 degrees) compared to asymptomatic horses (FE-T17 = 3.07 degrees, FE-L1 = 3.12 degrees). CONCLUSIONS: The objective measurement technique can detect differences between back kinematics in riding horses with signs of back dysfunction and asymptomatic horses. The clinical manifestation of back pain results in diminished flexion/extension movement at or near the thoracic lumbar junction. However, before applying the method more extensively in practice it is necessary to evaluate it further, including measurements of patients whose diagnoses can be confirmed and long-term follow-ups of back patients after treatment. POTENTIAL RELEVANCE: Since the objective measurement technique can detect small movement differences in back kinematics, it should help to clinically describe and, importantly, objectively detect horses with back pain and dysfunction.     

Compressive damage to the deep branch of the lateral plantar nerve associated with lameness caused by proximal suspensory desmitis

Objective— To describe pathologic changes in the deep branch of the lateral plantar nerve (DBLPN) of horses determined to be lame because of proximal suspensory desmitis (PSD), and to report the outcome after treatment by excision of a segment of the horses' DBLPN.
Study Design— Retrospective case series.
Animals— Adult horses (n=16).
Methods— Horses determined to be lame on one or both pelvic limbs because of PSD were treated by excision of a segment of the DBLPN, and 30 nerves were examined histologically. Owners were contacted to obtain information about the horses ≥6 months after surgery.
Results— Histologic changes suggestive of chronic nerve compression were identified in both nerves of 11 bilaterally lame horses and in the lame limb of 5 unilaterally lame horses. The nerve of the sound limb of 2 of 3 unilaterally lame horses that had bilateral nerve resection also had histologic changes compatible with nerve compression. Ten of 16 horses (62.5%) with follow-up information returned to soundness after excision of the DBLPN.
Conclusions— Pathologic changes of the DBLPN associated with compression may complicate PSD of the pelvic limbs. Excision of the nerve may resolve lameness caused by PSD.
Clinical Relevance— Horses lame because of PSD of the pelvic limb may remain lame after desmitis has resolved because of compression of the DBLPN. Excising a portion of this nerve may resolve lameness.     

Force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness.

OBJECTIVE: To evaluate the accuracy of force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness. MATERIAL AND METHODS: Nineteen healthy dogs and 41 dogs with low-grade unilateral hindlimb lameness due to stifle or hip joint problems were walked and trotted over a force plate. Peak vertical forces (PVF) were recorded, and a symmetry index (SI) was calculated from the PVF of the hindlimbs. 'Cut-off' values were determined from the SI of the normal dogs. These cut-off values were used to discriminate lame dogs from normal ones. Sensitivity and specificity were evaluated for measurements at walk and trot, and the Cohen's Kappa coefficient (k) was used to determine the agreement between clinical lameness and force plate measurements, and between force plate results at walk and trot. Receiver Operating Characteristics (ROC) curve were plotted for both gaits to evaluate accuracy. RESULTS: The sensitivity of the measurements at walk was 0.63, and specifity was 0.95. The sensitivity of the measurements at trot was 0.90, and specificity was 1.0. Moderate agreement was found between force plate measurements at walk and trot, and between clinical gait assessment and force plate measurements at walk. Good agreement was found between clinical gait assessment and measurements at trot. ROC analyses revealed the trot (94.7% [91.7%; 97.7%]) to be the more accurate test than the walk (85.0% [80.1%; 89.9%]). CONCLUSION: The trotting gait was more sensitive and accurate than the walking gait for the differentiation of dogs with a low-grade hindlimb lameness from normal ones using force plate gait analysis.     

Repeatability of back kinematics in horses during treadmill locomotion

We tested the hypothesis that repeatability of a standardised protocol for quantifying back kinematics is sufficiently high not to prevent its use in the clinical evaluation of horses with back problems. We investigated the extent to which differences between laboratories may affect the results when a standardised protocol is used. As a clinical tool, movement analysis techniques are helpful for the objective and quantitative assessment of kinematics. Knowledge about the repeatability of the kinematic data is very important. The present study investigates the repeatability of back kinematics in 10 sound horses over 5 successive days and in 2 laboratories (5 horses at each location). Measurements were performed on the treadmill during the walk and the trot. The between-stride, between-day and between-horse repeatability were determined. A high degree of between-stride and between-day repeatability was observed in the spatiotemporal parameters and in the time-angle diagrams of thoracic and lumbar vertebrae, the sacrum and the hindlimb during both the walk and trot. Much more variability was found between horses, with the highest degree of dissimilarity in the lateral bending rotation of the L1 vertebra. For range of motion values, the between-day coefficient of variability was <14% and the between-horse coefficient of variability was up to 4 times higher. Small differences were found in range of motion values between the 2 laboratories. It is concluded that an analysis of back kinematics in the horse can provide highly repeatable data, warranting clinical use.     

SCINTIGRAPHIC ASSESSMENT OF THE METACARPOPHALANGEAL AND METATARSOPHALANGEAL JOINTS OF HORSES WITH JOINT PAIN

Our aims were to evaluate the pattern of radiopharmaceutical uptake in horses with lameness related to the metacarpophalangeal and/or metatarsophalangeal joint and compare the results with similar information from sound horses. It was hypothesized that there would be a difference in radiopharmaceutical uptake between the lame and contralateral limb in unilaterally lame horses and that there would be a difference between lame and sound horses. Nuclear scintigraphic images of 43 horses with forelimb lameness and 30 horses with hindlimb lameness were evaluated. In all horses lameness was improved by intraarticular analgesia of the joint, or by perineural analgesia of the palmar/plantar (at the junction of the proximal 3/4 and the distal 1/4 of the metacarpal/metatarsal regions) and palmar/plantar metacarpal/metatarsal nerves. All images were assessed subjectively and a quantitative image analysis was performed by drawing a vertical line profile through the center of each joint in the lateral images and using region of interest analysis in both lateral and dorsal/plantar images. Ratios of radiopharmaceutical uptake were compared for each region between lame and contralateral limbs in unilaterally lame horses and between lame and control horses. There was a significant difference in the ratio of radiopharmaceutical uptake in the proximal aspect of the proximal phalanx between lame and nonlame forelimbs in unilaterally lame horses and in both lame and contralateral limbs of lame horses compared with control horses for the regions of the distal aspect of the third metacarpal/metatarsal bone and the proximal sesamoid bones. However, the profile analysis was of limited clinical value.     

Evaluation of discriminant analysis based on dorsoventral symmetry indices to quantify hindlimb lameness during over ground locomotion in the horse

Reasons for performing study: Advances in gait analysis techniques have led to assessment tools that can aid in detecting and quantifying lameness; here, bilateral tuberà coxae and pelvic movement during over ground locomotion are compared in order to investigate a practical method to assess hindlimb lameness in the horse. Objectives: To evaluate which parameters from anatomical landmarks on trunk and proximal hindlimbs are the best indicators of degree and side of hindlimb lameness. Methods: Fifteen horses (age 11–23 years, 6 nonlame and 9 unilaterally hindlimb lame horses 1/10 to 2/10 lame) were fitted with 4 inertial sensors: tuber sacrale, left and right tubera coxae and withers; 889 strides were collected from 6 trot trials per horse. Horses were assessed for lameness by a qualified equine orthopaedic surgeon from videos. Vertical displacement data for each sensor were used to calculate symmetry indices as well as published Fourier analysis based parameters. Linear discriminant analysis was used to determine the most discriminative parameters for 2 scenarios: grading of severity of lameness and identification of the affected limb. Results: Pelvic energy ratio gave the best indication for the degree of lameness. Directional symmetry index of the tubera coxae sensors yielded the highest discriminative power for identification of the lame limb. Conclusions and potential relevance: A good indication of the degree of hindlimb lameness can be obtained from vertical displacement data of the pelvic midline, collected from inertial sensors during over ground locomotion. The trunk mounted inertial sensor system allows for a time efficient collection of a representative database from horses with differing grade and site of lameness in a clinical setting. This is crucial for future work on a robust definition of the best parameters for lameness classification under practical conditions.     

Methodology and validity of assessing kinematics of the thoracolumbar vertebral column in horses on the basis of skin-fixated markers

OBJECTIVE: To determine the validity of using skin-fixated markers to assess kinematics of the thoracolumbar vertebral column in horses. ANIMALS: 5 Dutch Warmblood horses without abnormalities of the vertebral column. PROCEDURE: Kinematics of T6, T10, T13, T17, L1, L3, L5, S3, and both tuber coxae were determined by use of bone-fixated and skin-fixated markers. Three-dimensional coordinate data were collected while horses were walking and trotting on a treadmill. Angular motion patterns were calculated and compared on the basis of 2-dimensional analysis of data from skin-fixated markers and 3-dimensional analysis of data from bone-fixated markers. RESULTS: Flexion-extension of thoracolumbar vertebrae and axial rotation of the sacrum were satisfactorily determined at both the walk and trot, using skin-fixated markers. Data from skin-fixated markers were accurate for determining lateral bending at the walk in the midthoracic and lower lumbar portion of the vertebral column only. However, at the trot, data from skin-fixated markers were valid for determining lateral bending for all thoracolumbar vertebrae. CONCLUSIONS AND CLINICAL RELEVANCE: Caution should be taken when interpreting data obtained by use of skin-fixated markers on lateral bending motions during the walk in horses. For determination of other rotations at the walk and all rotations at the trot, use of skin-fixated markers allows valid calculations of kinematics of the vertebral column. Understanding to what extent movements of skin-fixated markers reflect true vertebral motion is a compulsory step in developing noninvasive methods for diagnosing abnormalities of the vertebral column and related musculature in horses.     

Idiopathic hopping‐like forelimb lameness syndrome in ridden horses: 46 horses (2002–2014)

There has been no analysis of a hopping‐type forelimb lameness syndrome seen in ridden horses. The objectives of this retrospective study were to describe the clinical features of this syndrome, response to diagnostic analgesia and imaging findings and to document post mortem findings. Clinical records from 2002 to 2014 were reviewed and data concerning signalment, history, lame limb(s), lameness characteristics, response to diagnostic analgesia and diagnostic imaging were recorded. There were 46 horses from 4 to 13 years of age, 6 of which had a history of known or suspected trauma immediately before the onset of reduced performance or lameness. Lameness seen when ridden was characterised by an intermittent shortened cranial phase of the step of the lame forelimb at the trot and marked elevation of the head as the affected limb was protracted, with the horse appearing to ‘hop’ (on the contralateral limb) as if trying to break to canter. When lameness was at its worst horses were unwilling to trot. Three horses showed sporadic severe stumbling. Local analgesia of the affected limb did not improve the lameness and in 16 horses lameness deteriorated. Three of 5 horses showed some improvement (≥2/8 grades) in the hopping‐type lameness after intra‐articular analgesia of the articular process joints of the sixth and seventh cervical vertebrae, ipsilateral to the lame forelimb. Radiographic, ultrasonographic and nuclear scintigraphic examinations were inconclusive. Two of 4 horses responded to treatment with gabapentin. In 3 horses post mortem examination revealed mild lymphocytic inflammation within or around the dorsal root ganglia of the fifth and sixth cervical nerve roots, sixth cervical nerve root or second thoracic nerve root ipsilateral to the lame limb. Idiopathic hopping‐type lameness syndrome in ridden horses may be a pain‐related condition ± a neurological component and currently has a guarded prognosis.