Vertical head and pelvic movement symmetry at the trot in dogs with induced supporting limb lameness

Development of an Artificial Neural Network for the Detection of Supporting Hindlimb Lameness: A Pilot Study in Working Dogs

Subjective lameness assessment has been a controversial subject given the lack of agreement between observers; this has prompted the development of kinetic and kinematic devices in order to obtain an objective evaluation of locomotor system in dogs. After proper training, neural networks are potentially capable of making a non-human diagnosis of canine lameness. The purpose of this study was to investigate whether artificial neural networks could be used to determine canine hindlimb lameness by computational means only. The outcome of this study could potentially assess the efficacy of certain treatments against diseases that cause lameness. With this aim, input data were obtained from an inertial sensor positioned on the rump. Data from dogs with unilateral hindlimb lameness and sound dogs were used to obtain differences between both groups at walk. The artificial neural network, after necessary adjustments, was integrated into a web management tool, and the preliminary results discriminating between lame and sound dogs are promising. The analysis of spatial data with artificial neural networks was summarized and developed into a web app that has proven to be a useful tool to discriminate between sound and lame dogs. Additionally, this environment allows veterinary clinicians to adequately follow the treatment of lame canine patients.

Displacement of center of mass in dogs in response to foot sensory stimulation

OBJECTIVE

Evaluate center of mass (CoM) displacement values during four-limb and three-limb standing with limb suspension in dogs before and after applying sensory stimulation to a forelimb or hindlimb.

STUDY DESIGN

Experimental study.

ANIMALS

Six clinically normal beagles.

METHODS

A four force-plate apparatus was built to assess static weight distribution. Dogs stood on the device with one limb in contact with each force plate. We created a plastic device to induce sensory stimulation so that lameness could not be detected visually when stimulating the paw. Experimenters confirmed the degree of lameness by walking before and after measurement. Body-weight shifts were induced via suspension of each limb and transient sensory stimulation to the right forelimb or left hindlimb. CoMs of five postures were compared, with and without transient sensory stimulation.

RESULTS

The four-limb CoM was located cranial to the center of the X- and Y-axis coordinates (X: -0.82 ± 9.12, Y: 61.00 ± 5.82). During three-limb standing with suspension of either forelimb, CoM shifted backward toward the contralateral side compared to four-limb standing. During hindlimb suspension, CoM shifted to the contralateral side. With right forelimb sensory stimulation, there were large CoM changes for both four-limb and three-limb standing (X: -34.53 ± 9.09, Y: 52.21 ± 6.88). CoM changes were small with left hindlimb sensory stimulation (X: 6.47 ± 13.86, Y: 69.41 ± 5.55).

CONCLUSION

CoMs during four-limb and three-limb standing were influenced by sensory stimulation of a forelimb and, to a lesser extent, of a hindlimb.

CLINICAL SIGNIFICANCE

Static evaluation of CoM may aid clinicians in the diagnosis and recovery of forelimb lameness.

The effect of a traditional and a stick gang-line on the body position of working sled dogs

This study aimed to investigate the effect of two different gang-lines on the pulling angle of sled dogs. It was hypothesised that dogs would run with a straighter angle of pull (in relation to the main-line) in stick gang-lines (STICK) than they would do in traditional gang-lines (TRAD). Eight sled dogs, divided into two teams, ran a 3.1 km trail twice in both types of gang-lines, pulling a quadbike on dry ground. Each dog remained in its team in the same position (side of gang line, and forward or back in the line) for both runs, using both types of lines in randomised order between the runs. Markers were placed on the dogs and on the main lines, and the runs were recorded by a video camera. The dogs’ angle of pull measured from the video recordings was compared between the two conditions. Thirteen positional measurements for each dog during each run were taken. The dogs were used to running in TRAD and were not acclimatised to STICK. Data was analysed using Wilcoxon and Spearmans rho tests. Data regarding individual dogs (n=13), teams (n=52), dogs’ placements in teams (n=4), and gang-line related pulling angles (n=104) was analysed. Overall, the position of the dogs was straighter when pulling in STICK, than when pulling in TRAD, with a median of 19° (inter quartile range (IQR) 24.75°) and 32° (IQR 25.75°), respectively (P<0.001). Between the two teams, there was no significant difference in pulling positions when running in STICK (P=0.543), but there was in TRAD (P<0.001). In individual assessment, six of the eight dogs ran in a straighter position (P=0.003 to 0.046) in STICK. Dogs running in the front of both teams pulled significantly straighter when in STICK (21°; IQR 23.75) than in TRAD (median 39°; IQR 18; P<0.001).

Analysis of Agile Canine Gait Characteristics Using Accelerometry

The high rate of severe injuries associated with racing greyhounds poses a significant problem for both animal welfare and the racing industry. Using accelerometry to develop a better understanding of the complex gait of these agile canines may help to eliminate injury contributing factors. This study used a single Inertial Measurement Unit (IMU) equipped with a tri-axial accelerometer to characterise the galloping of thirty-one greyhounds on five different race tracks. The dorsal-ventral and anterior-posterior accelerations were analysed in both the time and frequency domains. The fast Fourier transform (FFT) and Morlet wavelet transform were applied to signals. The time-domain signals were synced with the corresponding high frame rate videos of the race. It was observed that the acceleration peaks in the dorsal-ventral accelerations correspond to the hind-leg strikes which were noted to be fifteen times the greyhound's weight. The FFT analysis showed that the stride frequencies in all tracks were around 3.5 Hz. The Morlet wavelet analysis also showed a reduction in both the frequency and magnitude of signals, which suggests a speed reduction throughout the race. Also, by detecting abrupt changes along the track, the wavelet analysis highlighted potentially hazardous locations on the track. In conclusion, the methods applied in this research contribute to animal safety and welfare by eliminating the factors leading to injuries through optimising the track design and surface type.

Head and pelvic vertical displacement in dogs with induced swinging limb lameness: an experimental study

Background

Swinging limb lameness is defined as a motion disturbance ascribed to a limb in swing phase. Little is known about its biomechanics in dogs, particularly about the body motions that accompany it, such as vertical head and pelvic motion asymmetry. The aim of this study was to describe the changes in vertical head and pelvic motion asymmetry in dogs with induced swinging limb motion disturbance, mimicking a swinging limb lameness. Fore- and hind-limb lameness was induced in ten sound dogs by placing a weight (200 g) proximal to the carpus or tarsus, respectively. Marker-based motion capture by eight infrared light emitting video cameras recorded the dogs when trotting on a treadmill. Body symmetry parameters were calculated, including differences between the two highest positions of the head (HDmax) and pelvis (PDmax) and between the two lowest positions of the head (HDmin) and pelvis (PDmin), with a value of zero indicating perfect symmetry.

Results

Induction of swinging forelimb lameness showed significant changes in HDmax (median and range: sound 1.3 mm [− 4.7 to 3.1], in the left side − 28.5 mm [− 61.2 to − 17.9] and in the right side 20.1 mm [− 4.4 to 47.5]) and, induction of swinging hind limb lameness showed significant changes in PDmax (sound 2.7 mm [− 7.4 to 7.2], in the left side − 10.9 mm [− 22.4 to 0.5] and in the right side 8.6 mm [− 3 to 30]), as well as an increased hip movement asymmetry (sound 1.6 mm [− 8.6 to 19.9], in the left side − 18.1 mm [− 36.7 to 5.4] and in the right side 15 mm [− 20.7 to 32.1]) (P < 0.05).

Conclusions

Induced swinging fore- and hind limb lameness resulted in significant increased asymmetry of the maximal vertical displacement movement of the head and pelvis, due to decreased lifting of the head in forelimb lameness and of the pelvis in hind limb lameness. The results suggest that asymmetry of the maximal vertical displacement of the head and pelvis (i.e. lifting) is a key lameness sign to evaluate during examination of swinging limb lameness.

Inertial sensor-based system for lameness detection in trotting dogs with induced lameness

Lameness detection can be challenging in dogs, as reflected in the reported low inter-rater agreement when visually assessing lameness. The aim of this study was to use an inertial sensor-based system to detect and quantify induced distal and proximal limb disturbances mimicking supporting and swinging limb lameness in dogs trotting on a treadmill by measuring vertical head and pelvic movement symmetry. Ten clinically sound dogs were equipped with inertial measurement units that were attached to the head, pelvis and right distal forelimb. Vertical head and pelvic movement symmetry were measured while dogs trotted on a treadmill, before and after the induction of moderate support or swinging fore- and hindlimb lameness. Four symmetry variables were calculated: the differences in displacement between the two lowest and between the two highest values of the head and pelvis per stride, respectively. These variables were defined as minimum head difference (HDmin), maximum head difference (HDmax), minimum pelvic difference (PDmin) and maximum pelvic difference (PDmax). Induction of supporting forelimb and hindlimb lameness produced significant changes in HDmin and PDmin, respectively. Swinging forelimb and hindlimb lameness produced significant changes in HDmax and PDmax, respectively. Additional compensatory ipsilateral forelimb and contralateral hindlimb movements were detected. Based on our findings, inertial sensor-based systems can be used to detect and quantify induced moderate lameness and differentiate between supporting and swinging limb lameness in dogs trotting on a treadmill. Further studies are needed to evaluate this method in dogs presented for clinical lameness evaluation and in overground locomotion.