Force plate analysis of the walking gait in healthy dogs

Ground reaction forces, impulses, and their relationships to morphometric measurements were evaluated for walking gait in 17 healthy dogs. A force plate was used to record forces at 1-ms intervals. Vertical, craniocaudal, and mediolateral forces were measured and normalized by body weight. Impulses, defined as the total force applied over time, were calculated in vertical and craniocaudal directions. Craniocaudal impulses were further divided into braking and propulsion phases. Braking impulses were significantly greater in the forelimbs (P less than or equal to 0.001), whereas propulsion impulses were generally greater in the hind limbs. Impulses and peak forces were then compared with morphometric measurements (body weight, humeral and femoral lengths, and paw length). All relationships were linear, with correlation coefficients significant (P less than or equal to 0.001). As the size of the dog increased, braking, propulsion and vertical impulses increased. Conversely, as morphometric measurements increased, peak vertical forces decreased. Thus, larger dogs had a lower peak force on each limb, but had a higher total impulse applied during stance phase. As stance phase time increased, peak vertical forces decreased. The results indicated that healthy dogs had significant correlations between ground reaction forces, impulses, and morphometric measurements.     

Long-term temporal evaluation of ground reaction forces during development of experimentally induced osteoarthritis in dogs

OBJECTIVE: To describe changes in vertical ground reaction forces (GRF) over 48 months in dogs with osteoarthritis (OA) of the stifle joint induced by transection of a cranial cruciate ligament (CCL). ANIMALS: 12 clinically normal adult dogs. PROCEDURE: Vertical GRF (eg, peak force and impulse) were determined prior to and 1, 2, 3, 6, 10, and 12 months after transection of the right CCL. In 7 dogs, data were also collected 24, 32, 38, 42, and 48 months after transection. RESULTS: Vertical peak force and impulse were significantly decreased in the right hind limb at all times after transection, compared with baseline values. From 10 through 48 months after transection, vertical GRF remained essentially static. Ground reaction forces in the unoperated (left) hind limb also changed significantly during the study. Left vertical impulse significantly increased 3 months after transection, whereas at 24, 38, 42, and 48 months after transection, left vertical peak force was significantly decreased, compared with the baseline value. Mean intradog coefficients of variation (CV) for peak vertical force and impulse ranged from 738 and 9.32, respectively, 1 month after transection to 1.96 and 2.76, respectively, at 42 months. CONCLUSIONS AND CLINICAL RELEVANCE: Vertical GRF in the affected hind limb equilibrated approximately 10 months after CCL transection. Prior to this, force transmission across the affected stifle joint changed significantly over time. Intradog CV were small, indicating that GRF may be an appropriate outcome measurement for evaluation of OA development induced by CCL transection in dogs.     

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.     

Kinetic gait analysis of healthy dogs on two different surfaces

Objective— To determine the effects of 2 different, commonly used surfaces with different coefficients of friction on ground reaction forces in normal dogs.
Study Design— Prospective, observational, single cross-over study.
Animals— Dogs (n=10) with no gait abnormalities.
Methods— Dogs were acclimated to the force plate and 5 valid trials for each dog and each limb were recorded. Velocity and acceleration were tightly controlled. Each dog was tested on both surfaces sequentially in different sequences. Data analysis was done on peak vertical force, peak impulse, breaking and propulsion peak forces and impulses. Three-way repeated measures analysis of variance was used to separately evaluate the effect of floor type on force plate measures in fore and hind limbs, while controlling for side (left versus right) and experimental replicate. P -values<.05 were considered significant. Mean force and 95% confidence interval for the 6 variables analyzed for all limbs on each surface were calculated.
Results— There were no significant differences in ground reaction forces between the linoleum and the carpet surface for thoracic or pelvic limbs for all gait variables measured. There were no significant differences between each individual gait trial per dog between the right and left thoracic limbs trials nor differences between the right and left pelvic limb trials.
Conclusions— Normal dogs had no change in their ground reaction forces on linoleum and carpet surfaces.
Clinical Relevance— Kinetic results from multi-center or comparative trials will not be affected by use of either linoleum or carpet surfaces.     

Evaluation of gait kinetics in puppies with coxofemoral joint laxity

OBJECTIVE: To characterize ground reaction forces (GRFs) and determine whether there were correlations between forces and passive coxofemoral joint laxity in puppies. ANIMALS: Fifty-one 16-week-old hound-breed dogs. PROCEDURE: Force-plate gait evaluation and distraction radiographic imaging were performed. Ground reaction forces evaluated included x (mediolateral), y (craniocaudal breaking and propulsion), and z (vertical) peak force and impulse. Z-plane limb loading and unloading rates, loading interval, and weight distribution and y-plane stance time breaking and propulsion percentages were calculated. One-way ANOVA with the Duncan multiple range test was used to evaluate differences in gait variables among limbs. The relationships of left, right, highest, and mean distraction index (DI) with individual limb data of each dog were evaluated with the Spearman rank correlation. Left and right DIs were compared by means of linear regression analysis. RESULTS: Mean +/- SEM DI was 0.67 +/- 0.02. Left and right DIs were strongly correlated, but there were no significant relationships between DIs and gait variables. Most fore- and hind limb gait variables differed significantly, whereas paired fore- and hind limb gait variables did not. Asymmetry was most pronounced in the x- and y-planes. CONCLUSIONS AND CLINICAL RELEVANCE: GRFs were consistent with those of clinically normal mature dogs, supporting an absence of association between GRF and DI in young dogs. The GRFs and elucidation of the relationship between GRFs and DI may be useful for future studies in immature dogs.     

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.     

High speed field kinematics of foot contact in elite galloping horses in training

Reasons for performing study: Mechanical characterisation of the high speed gallop has significant importance for animal welfare and basic biology. Kinematic parameters such as the velocity of each foot at contact can inform theories of why animals gallop, and supplant epidemiological investigation into the mechanisms of musculoskeletal injury. Objective: To determine the velocity at which the fore and hind hooves of elite galloping horses impact the surface. Methods: High speed videography was used to measure the horizontal and vertical velocity of the hoof immediately prior to impact, and the subsequent sink (vertical) and slip (horizontal) distances travelled by the hoof into the surface. Horse speed ranged from 11–19 m/s. In total 170 forelimb and 168 hindlimb foot falls from 89 horses were analysed. Results: Horizontal and vertical hoof velocity increased with speed (P<0.001). Horizontal hoof velocity was significantly greater in the hindlimbs compared to the forelimbs (P<0.001) and was greater in the nonlead limbs compared to the lead limbs (P<0.001). Vertical hoof velocity was significantly greater in the lead limb than the nonlead limb (P<0.001). Overall, forelimbs contacted the ground with a more acute velocity vector angle than hindlimbs (P<0.001). Lead limbs contacted the ground at more acute angles than nonlead limbs (P<0.001). Vertical and horizontal velocities were highly correlated to sink and slip distance. Conclusion: Hindlimbs impact the surface at higher velocity than forelimbs, which is likely to result in higher peak impact forces in the hindlimbs. This runs counter to the finding of lower incidence of injury in hindlimbs. Potential relevance: Explanations consistent with these findings include the hindlimbs more effectively dampening peak impact forces, or that other injury mechanisms, such as limb vibration and limb load at mid stance, play an important role in injury.     

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.     

Kinetics and kinematics of the passage

Reasons for performing study: The load acting on the limbs and the load distribution between fore‐ and hindlimbs while performing specific dressage exercises lack objective assessment. Hypothesis: The greater a horse's level of collection, the more load is shifted to the rear and that during the passage the vertical load on the limbs increases in relation to the accentuated vertical movement of the centre of mass. Methods: Back and limb kinematics, vertical ground reaction force and time parameters of each limb were measured in 6 Grand Prix dressage horses performing on an instrumented treadmill at the trot and the passage. Horses were ridden by their own professional rider. Results: At the passage, horses moved at a slower speed (?43.2%), with a lower stride frequency (?23.6%) and, therefore, higher stride impulses (+31.0%). Relative stance duration of fore‐ and hindlimbs and suspension duration remained unchanged. While at the trot the diagonal limbs impacted almost simultaneously, the hindlimbs always impacted first at the passage; the time dissociation between landing and lift‐off remained unchanged. Because of the prolonged stride duration, stride impulse and consequently limb impulses were higher at the passage in the fore‐ as well as in the hindlimbs (+24.8% and +39.9%, respectively). Within the diagonal limb pair, load was shifted from the forehand to the hindquarters (percentage stride impulse carried by the forehand ?4.8%). Despite the higher impulses, peak vertical forces in the fore‐ and hindlimbs remained unchanged because of the prolonged absolute stance durations in fore‐ and hindlimbs (+28.1% and +32.2%, respectively). Conclusions: Based on the intralimb timing, the passage closely resembles the trot. Compared to other head‐neck positions, the higher degree of collection resulted in a pronounced shift in impulse towards the hindquarters. Despite the higher limb impulses, peak forces acting on the limbs were similar to those observed at the trot. Potential clinical relevance: An understanding of load distribution between fore‐ and hindlimbs in relation to different riding techniques is crucial to prevent wear‐and‐tear on the locomotor apparatus.     

Noninvasive determination of body segment parameters of the hind limb in Labrador Retrievers with and without cranial cruciate ligament disease

OBJECTIVE: To determine mass, center of mass (COM), and moment of inertia (ie, body segment parameters [BSPs]) of hind limb segments by use of a noninvasive method based on computerized tomography (CT) in Labrador Retrievers with and without cranial cruciate ligament (CCL) disease and to provide regression equations to estimate BSPs of normal, CCL-deficient, and contralateral hind limbs. ANIMALS: 14 clinically normal and 10 CCL-deficient Labrador Retrievers. PROCEDURES: Bone, muscle, and fat areas were identified via CT. Mass, COM, and moment of inertia were determined on the basis of tissue densities in the thigh, crus, and foot segments. Regression models were developed to determine predictive equations to estimate BSP on the basis of simple morphometric measurements. RESULTS: The thigh and crus of CCL-deficient limbs weighed less than in contralateral segments. Thighs weighed less in CCL-deficient than in normal limbs. The thigh moment of inertia was less in CCL-deficient than in contralateral limbs. The crural COM was located more distally in normal limbs, compared with other limbs. Predictive equations to estimate BSP varied by parameter, body segment, and limb status. CONCLUSIONS AND CLINICAL RELEVANCE: BSPs of the thigh and crus varied with segment and status of the hind limb in Labrador Retrievers with or without CCL disease. Equations to estimate BSP on the basis of simple morphometric measurements were proposed, providing a basis for nonterminal studies of inverse dynamics of the hind limbs in Labrador Retrievers. This approach may offer new strategies to investigate the pathogenesis of nontraumatic joint diseases.     

Force Plate Gait Analysis in Doberman Pinschers with and without Cervical Spondylomyelopathy

Background

The most accepted means of evaluating the response of a patient with cervical spondylomyelopathy (CSM) to treatment is subjective and based on the owner and clinician's perception of the gait.

Objective

To establish and compare kinetic parameters based on force plate gait analysis between normal and CSM‐affected Dobermans.

Animals

Nineteen Doberman Pinschers: 10 clinically normal and 9 with CSM.

Methods

Force plate analysis was prospectively performed in all dogs. At least 4 runs of ipsilateral limbs were collected from each dog. Eight force platform parameters were evaluated, including peak vertical force (PVF) and peak vertical impulse (PVI), peak mediolateral force (PMLF) and peak mediolateral impulse, peak braking force and peak braking impulse, and peak propulsive force (PPF) and peak propulsive impulse. In addition, the coefficient of variation (CV) for each limb was calculated for each parameter. Data analysis was performed by a repeated measures approach.

Results

PMLF (P = .0062), PVI (P = .0225), and PPF (P = .0408) were found to be lower in CSM‐affected dogs compared with normal dogs. Analysis by CV as the outcome indicated more variability in PVF in CSM‐affected dogs (P = 0.0045). The largest difference in the CV of PVF was seen in the thoracic limbs of affected dogs when compared with the thoracic limbs of normal dogs (P = 0.0019).

Conclusions and Clinical Importance

The CV of PVF in all 4 limbs, especially the thoracic limbs, distinguished clinically normal Dobermans from those with CSM. Other kinetic parameters less reliably distinguished CSM‐affected from clinically normal Dobermans.     

Effect of walking velocity on ground reaction force variables in the hind limb of clinically normal horses

OBJECTIVE: To measure the effect of subject velocity on hind limb ground reaction force variables at the walk and to use the data to predict the force variables at different walking velocities in horses. ANIMALS: 5 clinically normal horses. PROCEDURE: Kinematic and force data were collected simultaneously. Each horse was led over a force plate at a range of walking velocities. Stance duration and force data were recorded for the right hind limb. To avoid the effect of horse size on the outcome variables, the 8 force variables were standardized to body mass and height at the shoulders. Velocity was standardized to height at the shoulders and expressed as velocity in dimensionless units (VDU). Stance duration was also expressed in dimensionless units (SDU). Simple regression analysis was performed, using stance duration and force variables as dependent variables and VDU as the independent variable. RESULTS: Fifty-six trials were recorded with velocities ranging from 0.24 to 0.45 VDU (0.90 to 1.72 m/s). Simple regression models between measured variables and VDU were significant (R2 > 0.69) for SDU, first peak of vertical force, dip between the 2 vertical force peaks, vertical impulse, and timing of second peak of vertical force. CONCLUSION AND CLINICAL RELEVANCE: Subject velocity affects vertical force components only. In the future, differences between the forces measured in lame horses and the expected forces calculated for the same velocity will be studied to determine whether the equations can be used as diagnostic criteria.     

Clinical assessments of increased sensory sensitivity in dogs with cranial cruciate ligament rupture

Dogs with chronic pain have a compromised quality of life. Repeatable and accurate sensory assessments form a means by which the hypersensitivity likely to reflect chronic pain may be quantified. These assessments can be applied to individuals to identify those that may benefit from improved analgesic relief. In this study four sensory assessments were evaluated in dogs presenting with a naturally occurring chronic painful condition (cranial cruciate ligament rupture, CCLR) and were compared with healthy control animals of similar age and weight. Inter-digital von Frey filament and thermal sensitivity tests revealed that the affected hind limb of dogs with CCLR was significantly more sensitive than the opposing limb. Static weight bearing and gait parameter scores were also reduced in the affected hind limb compared to the opposing hind limb of dogs with CCLR; no such differences were found between the hind limbs of healthy (control) dogs. The quantitative sensory tests permitted the differentiation of limbs affected by CCLR from healthy limbs. Dogs presenting with CCLR demonstrate objectively quantitative sensory sensitivities, which may require additional consideration in case management.     

Effect of hind limb position on the craniocaudal length of the lumbosacral space in anesthetized dogs

Objective To investigate whether rostral extension of the hind limbs increases the cranio‐caudal dorsal interlaminar distance between the seventh lumbar vertebra and the sacral bone (LS distance) in sternally recumbent anesthetized dogs. Study design Prospective clinical study. Animals Eighteen dogs (eight neutered males, three intact males, six spayed females, one intact female) of various breeds, weighing 4–34 kg and ranging in age from 1 to 13 years. Methods Each dog was grouped by size: small (≤10 kg), medium (15–20 kg) or large (≥25 kg). Each dog was anesthetized and positioned in sternal recumbency. Computed tomography (CT) of the lumbosacral area was performed with the hind limbs resting on the stifle and the feet extended posteriorly, and then with the hind limbs extended rostrally. LS distance, craniocaudal dorsal interlaminar distance between sixth and seventh lumbar vertebra (L6–L7 distance), length of L7 vertebral body and lumbosacral angle (LS angle) were measured on a reconstructed mid‐sagittal CT image from the two hind limb positions. The measurements from the two hind limb positions for the whole dog population and by size were compared using Student’s T tests. Diagnostic interpretation of the CT images was performed. Results The length of L7 was taken as the reference value as it was not affected by hind limb position. LS distance, L6–L7 distance and LS angle were significantly higher when the hind limbs were extended rostrally in all three size groups. The CT images of ten dogs showed clinically undetected osteoarthrosis of the ileo‐ and lumbosacral area. Conclusions and clinical relevance Rostral extension of the hind limbs significantly increases LS and L6–L7 distance and LS angle even in dogs with clinically undetected osteoarthrosis of the ileo‐ and lumbosacral area, and may enhance the ease of lumbosacral epidural injection in sternally recumbent anesthetized dogs.     

Temporospatial and kinetic characteristics of sheep walking on a pressure sensing walkway

The walking gait of sheep was analyzed in terms of temporospatial and kinetic parameters and weight distribution among the 4 limbs. Eighteen mature female Suffolk-mix sheep walked comfortably with a halter-guide over a 1.5-m pressure sensing walkway. Six valid trials were acquired for each sheep without any previous selection or habituation. Stance phases of the forelimb and hind limb were 66.3% and 68.9%, respectively, of total gait cycle, and limb velocity was 1.06 m/s in both forelimbs and hind limbs while walking. The mean peak vertical force (PVF) and vertical impulse (VI) as percentage of body weight in the forelimbs were 52.5% and 19.9%, respectively, and those of the hind limbs were 38.5% and 14.9%, respectively. More body weight was loaded on the forelimbs than the hind limbs, at 59% and 41% of body weight, respectively. The walking gait of sheep measured with the pressure sensing (PS) walkway was similar to that reported in dogs and horses. The PS walkway enabled collection of temporospatial and kinetic data, and simplified the process of data collection.     

Distribution of vertical forces in the pads of Greyhounds and Labrador Retrievers during walking

OBJECTIVE: To document peak vertical force (PVF) and vertical impulse (VI) in the pads of Greyhounds and Labrador Retrievers. ANIMALS: 8 Greyhounds and 8 Labrador Retrievers. PROCEDURE: Velocity and acceleration were restricted to ranges of 0.9 to 1.1 m/s and -0.1 to 0.1 m/s2, respectively. The PVF and VI measurements were collected from digital pad (DP)-2, -3, -4, and -5 and the metacarpal pad (McP) or metatarsal pad (MtP) of each limb in each dog. RESULTS: We found no significant differences between the left and right forelimbs or hind limbs for any pad in either breed. Vertical forces in the forelimb were always greater than those in the hind limb. The PVF in the forelimbs of Greyhounds was greatest in DP-3, -4, and -5 and DP-3, DP-4, and the MtP in the hind limbs. The VI in Greyhound forelimbs was greatest in DP-3, -4, and -5 but greatest in DP-4 in the hind limbs. The PVF in the forelimbs of Labrador Retrievers was greatest in the McP, whereas in the hind limbs it was greatest in DP-4. The VI in Labrador Retriever forelimbs was greatest in DP-3, DP-4, and the McP but greatest in DP-3 and -4 in the hind limbs. Significant differences were detected in load distribution between the breeds. CONCLUSIONS AND CLINICAL RELEVANCE: This study confirms that DP-3 and DP-4 are major weight-bearing pads in dogs. However, loads were fairly evenly distributed, and DP-5 and the McP or MtP bear a substantial amount of load in both breeds.     

Computer-assisted kinematic evaluation of induced compensatory movements resembling lameness in horses trotting on a treadmill

OBJECTIVE: To characterize compensatory movements of the head and pelvis that resemble lameness in horses. ANIMALS: 17 adult horses. PROCEDURE: Kinematic evaluations were performed while horses trotted on a treadmill before and after shoe-induced lameness. Lameness was quantified and the affected limb determined by algorithms that measured asymmetry in vertical movement of the head and pelvis. Induced primary lameness and compensatory movements resembling lameness were assessed by the Friedman test. Association between induced lameness and compensatory movements was examined by regression analysis. RESULTS: Compensatory movements resembling lameness in the ipsilateral forelimb were seen with induced lameness of a hind limb. There was less downward and less upward head movement during and after the stance phase of the ipsilateral forelimb. Doubling the severity of lameness in the hind limb increased severity of the compensatory movements in the ipsilateral forelimb by 50%. Compensatory movements resembling lameness of the hind limb were seen after induced lameness in a forelimb. There was less upward movement of the pelvis after the stance phase of the contralateral hind limb and, to a lesser extent, less downward movement of the pelvis during the stance phase of the ipsilateral hind limb. Doubling the severity of lameness in the forelimb increased compensatory movements of the contralateral hind limb by 5%. CONCLUSIONS AND CLINICAL RELEVANCE: Induced lameness in a hind limb causes prominent compensatory movements resembling lameness in the ipsilateral forelimb. Induced lameness in a forelimb causes slight compensatory movements resembling lameness in the ipsilateral and contralateral hind limbs.     

Ground reaction force analysis of large breed dogs when walking after the amputation of a limb

Force plate analysis was used to measure ground reaction forces (GRF) and contact times, and calculate the centre of gravity at a walk of 10 dogs which had had a limb amputated, and the results were compared with the results from 22 normal dogs of the same weight. The loss of a limb caused significant changes in the GRF, impulses and contact times of the remaining limbs and in the location of the dogs' centre of gravity. The changes were greater in dogs which had lost a forelimb than in dogs which had lost a hindlimb.     

Ground reaction forces and limb function in tölting Icelandic horses

REASONS FOR PERFORMING STUDY: Gaited horses employ 4-beat stepping (singlefoot) gaits that extend into speeds typical of trots. Ground reaction force (GRF) patterns of these specialised gaits have not been reported; therefore, appraisal of these gaits using nongaited horse kinetics may lead to clinical misjudgements. HYPOTHESIS: GRFs of t?lting Icelandic horses will be comparable in profile and magnitude with those of trotting horses. METHODS: Forelimb and hindlimb GRFs were obtained for 10 Icelandic horses ridden at a t?lt. These data were evaluated across 3 speed ranges: <2, 2.5-5 and >5 m/sec. RESULTS: Virtually all vertical force tracings were single-peaked. Forelimbs typically had greater peak vertical forces and impulses compared with hindlimbs. Support duration and forelimb vertical impulse were correlated negatively with speed, whereas peak vertical, braking and propulsive forces and hindlimb braking and propulsive impulses were correlated positively with speed. CONCLUSIONS: GRF profiles of t?lting Icelandic horses are more similar to profiles of trots than walks, suggesting that t?lts follow bouncing mechanics. POTENTIAL RELEVANCE: Greater overlap of limb support in 4-beat gaits (even at high speeds) is associated with lower peak vertical force magnitudes of t?lts compared with those reported for trots at comparable speeds, which may help limit the occurrence of overloading injuries in Icelandic horses.     

Objective determination of pelvic movement during hind limb lameness by use of a signal decomposition method and pelvic height differences

OBJECTIVE: To evaluate pelvic movement over a large number of strides in sound horses and in horses with induced hind limb lameness by applying methods to the pelvis that have been described for evaluating vertical head movement in horses with induced forelimb lameness. ANIMALS: 17 adult horses. PROCEDURE: Horses were filmed while trotting on a treadmill before and after induction of transient mild and moderate hind limb lamenesses. Vertical pelvic movement was measured by a signal decomposition method. The vertical pelvic signal was decomposed into a periodic component (A1) that occurred at half the stride frequency (representing vertical pelvic movement caused by lameness) and another periodic component (A2) that occurred at stride frequency (representing normal vertical pelvic movement of a trotting horse). Vertical pelvic and foot positions were correlated for each stride to compare the difference between the minimum and maximum heights of the pelvis during and after stance of the right hind limb to the minimum and maximum heights of the pelvis during and after stance of the left hind limb. RESULTS: Maximum pelvic height difference and lameness amplitude (A1) differed significantly between sound and mild or moderate hind limb lameness conditions. Mean A1 value for vertical pelvic movement in sound horses was less than that previously reported for vertical head movement. CONCLUSION AND CLINICAL RELEVANCE: Pelvic height differences and signal decomposition of pelvic movement can be used to objectively evaluate hind limb lameness in horses over a large number of strides in clinical and research settings.