Objective—To evaluate an adaptive-filter method for
use in analysis of periodic electromyography (EMG)
signals in which the transfer function of the filter is
matched to characteristics of the signal.
Animals—15 adult horses without clinical signs of
Procedure—Electromyography signals of the left and
right longissimus dorsi muscles, middle gluteal muscles,
and triceps brachii muscle were recorded from
horses walking on a treadmill, using bilaterally placed
surface electrodes. A reflective marker was placed on
the hoof of the left hind limb for simultaneous kinematic
measurement of motion cycles. Absolute value
of the measured EMG signal was convoluted by use
of a filter signal equivalent to the length of 3 motion
cycles. The signal-to-noise ratio (SNR) was calculated
from the autocorrelation function and compared with
the SNR of the unfiltered and the low-pass filtered
Results—The signal-adapted filter significantly
increased SNR (by 7.3 dB, compared with the lowpass
filter, and by 11.1 dB, compared with the unfiltered
Conclusions and Clinical Relevance—The signal adapted
filter eliminates signal parts that are not correlated
to periodic motion. The method reported here
improves the applicability of periodic EMG signals as
a clinical tool. (Am J Vet Res 2001;62:1687–1689)
Objective—To evaluate back movement during walking
Animals—22 adult horses with no history or signs of
Procedure—3-dimensional movements of markers
on the hooves, head, and back were measured with a
motion analysis system while the horses were walking
on a treadmill. The positions of markers on the
hooves, head, and the skin above the spinous
processes of T5, T10, T16, L3, and 2 sacral vertebrae
were recorded. From a minimum of 6 walking motion
cycles/horse, marker movement and the time of
occurrence of minimum and maximum marker positions
within the motion cycle were determined.
Angles were calculated between the markers on the
head, T16, and S4 or S5 and between the markers on
T5, T16, and S4 or S5.
Results—Lateral back movement was maximal at L3,
where it reached (mean ± SD) 3.5 ± 0.8% of the horses'
height at the withers. Maximum dorsoventral
back movement was found at the sacrum, where it
reached 4.7 ± 1.3% of the height at the withers. In
the horizontal plane, the angle between T5, T16, and
S4 or S5 was altered by 11 ± 2.5° during the motion
cycle. In the sagittal plane, the angle between the
head, T16, and S4 or S5 was altered by 7 ± 3°.
Conclusions and Clinical Relevance—Results of
this study may be used as basic kinematic reference
data for evaluation of back movement in horses. (Am
J Vet Res 2001;62:1173–1179)
Objective—To use electromyography (EMG) to measure
physiologic activity of the longissimus dorsi muscles
of horses during trotting on a treadmill.
Animals—15 adult horses (5 to 20 years old that
weighed 450 to 700 kg) that did not have clinical signs
of back pain.
Procedure—Data were recorded for each horse during
trotting on a treadmill at speeds of 2.6 to 4.4 m/s.
Surface electromyography was recorded bilaterally
from the longissimus dorsi muscles at the levels of
T12, T16, and L3.
Results—In each motion cycle, 2 EMG maxima were
found at the end of the diagonal stance phases. The
EMG activity peaked slightly later at L3 than at T12
and T16. Maximum EMG amplitudes were highest at
T12 and decreased caudally, with mean ± SD values
of 4.51 ± 1.20 mV at T12, 3.00 ± 0.83 mV at T16, and
1.78 ± 0.67 mV at L3. Mean minimum EMG activity
was 1.30 ± 0.63 mV at T12, 0.83 ± 0.35 mV at T16, and
0.80 ± 0.39 mV at L3. The relative amplitudes (ie,
[maximum – minimum]/maximum) were 67 ± 11% at
T12, 66 ± 8% at T16, and 71 ± 8% at L3.
Conclusions and Clinical Relevance—Activity of the
longissimus dorsi muscles is mainly responsible for
stabilization of the vertebral column against dynamic
forces. The difference between minimum and maximum
activity may allow application of this method as
a clinical tool. Data reported here can serve as reference
values for comparison with values from clinically
affected horses. (Am J Vet Res 2004;65:155–158)
Objective—To evaluate the applicability of Fourier analysis for assessment of ground reaction forces (GRFs) and differentiation between dogs with unilateral hind limb lameness caused by degenerative joint disease of the hip (DJD-H) and dogs without lameness.
Animals—37 dogs with or without unilateral DJD-H.
Procedures—Data were obtained from other studies and analyzed retrospectively. Among the 37 dogs, 20 had unilateral DJD-H and 9 (non–Belgian Malinois breeds) had no lameness; another 8 were nonlame Belgian Malinois (radiographically confirmed Fédération Cinologique International classification A [ie, no hip dysplasia or DJD-H]). Gait data acquisition was performed as dogs walked on a treadmill with integrated force platforms. The peak vertical force, mean vertical force, and vertical impulse were compared among the 3 groups. Fourier analysis was performed on the force-time curves for the vertical GRF, and calculated Fourier coefficients were compared within and between groups.
Results—Lameness in the hind limbs with DJD-H was detectable via conventional analysis of the GRF as well as via Fourier analysis. However, subtle gait aberrations in the forelimbs of the dogs with DJD-H were detected solely via Fourier analysis of GRFs and remained undetected via conventional analysis.
Conclusions and Clinical Relevance—Results support the applicability of Fourier analysis for evaluation of force-time curves of GRFs. Fourier analysis can reveal subtle alterations of gait that might otherwise remain inapparent; however, further investigation is necessary before this method can be routinely applied for lameness detection in dogs.
Objective—To detect changes in joint kinematics of clinically sound dogs with or without radiographically detectable borderline hip dysplasia (HD).
Animals—20 Belgian Shepherd Dogs (Malinois; mean ± SD age, 2.75 ± 1.32 years) with no clinical signs of HD.
Procedures—Kinematic gait analysis was performed in Malinois walking on a treadmill. On the basis of results of radiographic examination for HD and in accordance with guidelines established by the Fédération Cynologique Internationale, dogs were assigned to group 1 (no radiographic signs of HD; 8 dogs) or group 2 (borderline HD; 12 dogs). Ground reaction forces and weight distribution among limbs and differences between groups were evaluated. Maximal sagittal angle during the stance and swing phases, the time at which they were detected, and angle velocities were calculated for joints of the hind limbs.
Results—Ground reaction forces revealed no differences between groups. Dogs in group 1 had significant changes (earlier time for maximal flexion of the hip joint and less flexion and less range of motion of the stifle joint), compared with results for dogs in group 2. Maximal angle velocity of the stifle and tarsal joints was significantly lower during the swing phase in group 1 than in group 2.
Conclusions and Clinical Relevance—This study revealed that dogs with borderline HD had altered joint kinematics. Our data provide basic kinematic values for clinically sound and affected dogs and can be used to investigate the long-term effects for subclinical radiographic changes of the hip joints of dogs.
Objective—To determine the skin temperature of the metacarpus in horses associated with the use of bandages and tendon boots, compared with the bare limb, at rest and after 20 minutes of lunging.
Animals—10 adult horses.
Procedures—Skin temperature on the bare metacarpus of both forelimbs was measured at rest and after lunging. Subsequently, a bandage was applied to the left metacarpus and a tendon boot to the right metacarpus and skin temperature was measured at rest and after lunging. Skin temperature was measured with fixed sensors and thermographically.
Results—Mean ± SD skin temperatures of the bare metacarpi were 14.1 ± 2.4°C (left) and 14.1 ± 3.4°C (right) at rest, and 14.4 ± 1.8°C (left) and 13.6 ± 2.6°C (right) after exercise. Skin temperatures under the bandage were 15.3 ± 1.6°C at rest and 24.8 ± 3.6°C after exercise. Skin temperatures under the tendon boot were 15.3 ± 2.6°C at rest and 20.6 ± 2.9°C after exercise. Skin temperatures under the bandage and tendon boot were significantly higher after exercise than at rest. Skin temperatures at rest were not significantly different with a bare limb, bandage, or tendon boot.
Conclusions and Clinical Relevance—Skin temperature of the metacarpus in horses increased significantly during exercise but not at rest when a bandage or tendon boot was used. The authors speculate that both a bandage and a tendon boot accelerate the warmup phase of exercise. Further research should focus on the effects of warmup and maximum exercise on the temperature of other anatomic structures such as tendons.
Objective—To assess differences in activities of back and pelvic limb muscles by use of surface electromyography (SEMG) in chronically lame and nonlame horses during walking and trotting.
Animals—12 nonlame horses and 12 horses with unilateral chronic mild to moderate pelvic limb lameness.
Procedures—On each horse, bipolar electrodes were attached to the skin over the midpoints of the right and left longissimus thoracis (Lot), semitendinosus (Set), biceps femoris (Bif), gluteus medius (Glm), and extensor digitorum longus (Edl) muscles. For each muscle, synchronous kinematic and SEMG recordings were made during walking and trotting on a treadmill; mean, maximum, and minimum muscle activities and maximum-to-mean and minimum-to-mean activity ratios were determined. For each lame or nonlame horse, data from both pelvic limbs were averaged; in lame horses, data from the nonlame and lame pelvic limbs were also examined separately (NL-L and L-L values, respectively). Comparisons were made among the 4 data sets and between gaits.
Results—During walking, the NL-L maximum-to-mean ratios for Bif and Glm muscles were significantly greater and in lame horses, L-L and NL-L minimum-to-mean ratios for Set, Bif, Glm, and Lot muscles were significantly less than those for nonlame horses. During trotting, minimum-to-mean ratios for Set, Glm, and Lot muscles in lame horses were significantly lower than those for nonlame horses. Activity of the Edl muscle was not affected by lameness.
Conclusions and Clinical Relevance—In lame horses, variation in muscle use was detectable via SEMG. In chronically lame horses, back and pelvic limb muscle activities were affected differently during walking and trotting.
Objective—To assess forelimbs and hind limb joint kinematics in dogs during walking on an inclined slope (uphill), on a declined slope (downhill), or over low obstacles (cavaletti) on a horizontal surface and compare findings with data acquired during unimpeded walking on a horizontal surface.
Procedures—By use of 10 high-speed cameras and 10 reflecting markers located on the left forelimbs and hind limbs, joint kinematics were recorded for each dog during uphill walking, downhill walking, and walking over low obstacles or unimpeded on a horizontal surface. Each exercise was recorded 6 times (10 s/cycle); joint angulations, angle velocities and accelerations, and range of motion for shoulder, elbow, carpal, hip, stifle, and tarsal joints were calculated for comparison.
Results—Compared with unimpeded walking, obstacle exercise significantly increased flexion of the elbow, carpal, stifle, and tarsal joints and extension in the carpal and stifle joints. Only uphill walking caused increased hip joint flexion and decreased stifle joint flexion; downhill walking caused less flexion of the hip joint. During obstacle exercise, forward angle velocities in the elbow and stifle joints and retrograde velocity in the tarsal joint changed significantly, compared with unimpeded walking. Joint angle acceleration of the elbow joint changed significantly during all 3 evaluated exercises.
Conclusions and Clinical Relevance—These evidence-based data indicated that each evaluated exercise, except for downhill walking, has a specific therapeutic value in physical therapy for dogs.
Objective—To assess joint kinematics in dogs with osteoarthritis of the hip joints during walking up an incline or down a decline and over low obstacles and to compare findings with data for nonlame dogs.
Animals—10 dogs with osteoarthritis of the hip joints (mean ± SD age, 6.95 ± 3.17 years; mean body weight, 34.33 ± 13.58 kg) and 8 nonlame dogs (3.4 ± 2.0 years; 23.6 ± 4.6 kg).
Procedures—Reflective markers located on the limbs and high-speed cameras were used to record joint kinematics during walking up an incline or down a decline and over low obstacles. Maximal flexion, extension, and range of motion of the hip joints were calculated.
Results—Osteoarthritis of the hip joints reduced extension of both hip joints and flexion of the contralateral hind limb, compared with flexion of the lame hind limb, during walking down a decline. Walking up an incline resulted in decreased extension of the stifle joint in both hind limbs of osteoarthritic dogs; extension was significantly decreased for the lame hind limb. During walking over low obstacles, maximal flexion of the stifle joint was increased significantly for the contralateral hind limb. Maximal flexion was increased in both tarsal joints.
Conclusions and Clinical Relevance—Osteoarthritis of the hip joints led to complex changes in the gait of dogs, which involved more joints than the affected hip joint alone. Each exercise had specific effects on joint kinematics that must be considered when planning a rehabilitation program.