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Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs’ global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs’ pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs’ ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPPTL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPPPL). The positions of VPPs and the patterns of the limbs’ axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPPPL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPPTL or the horizontal position of VPPPL. The vertical position of VPPPL was only influenced by gait, while the horizontal position of VPPTL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions’ predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.

Abstract Background French bulldogs exhibit significantly larger femoral external rotation and abduction than other breeds. We were curious as to whether this peculiar leg kinematic affects patellar motion and/or might induce medial patellar subluxation (MPSL) or medial patellar permanent luxation (MPPL). We hypothesized that the more abducted leg posture during stance causes an unusual medial pull direction of the rectus femoris muscle during stance, and that this may facilitate the occurrence of MPSL or even MPPL during locomotion. To test our hypothesis, we analyzed existing stifle-joint X-ray-sequences collected during the treadmill walk and trot of seven adult female French bulldogs. We estimated 3D-patellar kinematics using Scientific Rotoscoping. Results The three-dimensional motion of the patella comprises rotations and translations. From the seven dogs analyzed, three exhibited MPSL and one MPPL during the gait cycle. Medial patellar luxation (MPL) occurred mostly around toe-off in both gaits studied. Patellar position was generally not gait-related at the analyzed timepoints. In dogs with MPL, the patella was placed significantly more distally (p = 0.037) at touch-down (TD) and at midswing (p = 0.024), and significantly more medial at midswing (p = 0.045) compared to dogs without MPL. Conclusions Medial patellar luxation seems to be the consequence of the far from parasagittal position of the stifle joint during stance due to a broad trunk, and a wide pelvis. This peculiar leg orientation leads to a medial sideway pull caused by the rectus femoris muscle and the quadriceps femoris and may initiate plastic deformation of the growing femur and tibia. Thus, a way to avoid MPL could be to control breeding by selecting dogs with lean bodies and narrow pelvis. Actual breeding control programs based on the orthopedic examination are susceptible to errors. Systematic errors arise from the fact that the grading system is highly dependent on the dog’s condition and the veterinarians’ ability to perform the palpation on the stifle. Based on our results, the position of the patella at TD, or even perhaps during stand might offer a possibility of an objective radioscopic diagnostic of the MPL.

Lumbosacral vertebral motion is thought to be a factor in the development of degenerative lumbosacral stenosis in German shepherd dogs. So far, few studies exist describing natural canine lumbosacral movement in vivo. Therefore, this investigation aims to achieve a detailed in vivo analysis of bone movement of the lumbosacral region to gain a better understanding of the origin of degenerative lumbosacral stenosis using three-dimensional non-invasive in vivo analysis of canine pelvic and caudal lumbar motion (at L6 and L7). Biplanar cineradiography of the pelvis and caudal lumbar spine of four clinically sound German shepherd dogs at a walk and at a trot on a treadmill was recorded. Pelvic and intervertebral motion was virtually reconstructed and analyzed with scientific rotoscoping. The use of this technique made possible non-invasive measurement of physiological vertebral motion in dogs with high accuracy. Furthermore, the gait patterns of the dogs revealed a wide variation both between individual steps and between dogs. Pelvic motion showed a common basic pattern throughout the stride cycle. Motion at L6 and L7, except for sagittal rotation at a trot, was largely asynchronous with the stride cycle. Intervertebral motion in all dogs was small with approximately 2–3° rotation and translations of approximately 1–2 mm. The predominant motion of the pelvis was axial rotation at a walk, whereas lateral rotation was predominant at a trot. L7 showed a predominance of sagittal rotation (with up to 5.1° at a trot), whereas lateral rotation was the main component of the movement at L6 (about 2.3° in both gaits). During trotting, a coupling of various motions was detected: axial rotation of L7 and the pelvis was inverse and was coupled with craniocaudal translation of L7. In addition, a certain degree of compensation of abnormal pelvic movements during walking and trotting by the caudal lumbar spine was evident.

All vertebrate species have a distinct morphology and movement pattern, which reflect the adaption of the animal to its habitat. Yet, our knowledge of motion patterns of the craniocervical junction of dogs is very limited. The aim of this prospective study is to perform a detailed analysis and description of three-dimensional craniocervical motion during locomotion in clinically sound Chihuahuas and Labrador retrievers. This study presents the first in vivo recorded motions of the craniocervical junction of clinically sound Chihuahuas (n = 8) and clinically sound Labrador retrievers (n = 3) using biplanar fluoroscopy. Scientific rotoscoping was used to reconstruct three-dimensional kinematics during locomotion. The same basic motion patterns were found in Chihuahuas and Labrador retrievers during walking. Sagittal, lateral, and axial rotation could be observed in both the atlantoaxial and the atlantooccipital joints during head motion and locomotion. Lateral and axial rotation occurred as a coupled motion pattern. The amplitudes of axial and lateral rotation of the total upper cervical motion and the atlantoaxial joint were higher in Labrador retrievers than in Chihuahuas. The range of motion (ROM) maxima were 20°, 26°, and 24° in the sagittal, lateral, and axial planes, respectively, of the atlantoaxial joint. ROM maxima of 30°, 16°, and 18° in the sagittal, lateral, and axial planes, respectively, were found at the atlantooccipital joint. The average absolute sagittal rotation of the atlas was slightly higher in Chihuahuas (between 9.1 ± 6.8° and 18.7 ± 9.9°) as compared with that of Labrador retrievers (between 5.7 ± 4.6° and 14.5 ± 2.6°), which corresponds to the more acute angle of the atlas in Chihuahuas. Individual differences for example, varying in amplitude or time of occurrence are reported.

The domestic dog is interesting to investigate because of the wide range of body size, body mass, and physique in the many breeds. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. Collecting this data through in vivo measurements/records of joint forces and loads on deep/small muscles is complex, invasive, and sometimes unethical. The use of detailed musculoskeletal models may help fill the knowledge gap. We describe here the methods we used to create a detailed musculoskeletal model with 84 degrees of freedom and 134 muscles. Our model has three key-features: three-dimensionality, scalability, and modularity. We tested the validity of the model by identifying forelimb muscle synergies of a walking Beagle. We used inverse dynamics and static optimization to estimate muscle activations based on experimental data. We identified three muscle synergy groups by using hierarchical clustering. The activation patterns predicted from the model exhibit good agreement with experimental data for most of the forelimb muscles. We expect that our model will speed up the analysis of how body size, physique, agility, and disease influence neuronal control and joint loading in dog locomotion. [ABSTRACT FROM AUTHOR]

Background: French bulldogs exhibit significantly larger femoral external rotation and abduction than other breeds. We were curious as to whether this peculiar leg kinematic affects patellar motion and/or might induce medial patellar subluxation (MPSL) or medial patellar permanent luxation (MPPL). We hypothesized that the more abducted leg posture during stance causes an unusual medial pull direction of the rectus femoris muscle during stance, and that this may facilitate the occurrence of MPSL or even MPPL during locomotion. To test our hypothesis, we analyzed existing stifle-joint X-ray-sequences collected during the treadmill walk and trot of seven adult female French bulldogs. We estimated 3D-patellar kinematics using Scientific Rotoscoping. Results: The three-dimensional motion of the patella comprises rotations and translations. From the seven dogs analyzed, three exhibited MPSL and one MPPL during the gait cycle. Medial patellar luxation (MPL) occurred mostly around toe-off in both gaits studied. Patellar position was generally not gait-related at the analyzed timepoints. In dogs with MPL, the patella was placed significantly more distally (p = 0.037) at touch-down (TD) and at midswing (p = 0.024), and significantly more medial at midswing (p = 0.045) compared to dogs without MPL. Conclusions: Medial patellar luxation seems to be the consequence of the far from parasagittal position of the stifle joint during stance due to a broad trunk, and a wide pelvis. This peculiar leg orientation leads to a medial sideway pull caused by the rectus femoris muscle and the quadriceps femoris and may initiate plastic deformation of the growing femur and tibia. Thus, a way to avoid MPL could be to control breeding by selecting dogs with lean bodies and narrow pelvis. Actual breeding control programs based on the orthopedic examination are susceptible to errors. Systematic errors arise from the fact that the grading system is highly dependent on the dog's condition and the veterinarians' ability to perform the palpation on the stifle. Based on our results, the position of the patella at TD, or even perhaps during stand might offer a possibility of an objective radioscopic diagnostic of the MPL. [ABSTRACT FROM AUTHOR]

Knowledge about the mechanisms underlying canine vision is far from being exhaustive, especially that concerning post-retinal elaboration. One aspect that has received little attention is motion perception, and in spite of the common belief that dogs are extremely apt at detecting moving stimuli, there is no scientific support for such an assumption. In fact, we recently showed that dogs have higher thresholds than humans for coherent motion detection (Kanizsar et al. in Sci Rep UK 7:11259, 2017). This term refers to the ability of the visual system to perceive several units moving in the same direction, as one coherently moving global unit. Coherent motion perception is commonly investigated using random dot displays, containing variable proportions of coherently moving dots. Here, we investigated the relative contribution of local and global integration mechanisms for coherent motion perception, and changes in detection thresholds as a result of repeated exposure to the experimental stimuli. Dogs who had been involved in the previous study were given a conditioned discrimination task, in which we systematically manipulated dot density and duration and, eventually, re-assessed our subjects’ threshold after extensive exposure to the stimuli. Decreasing dot duration impacted on dogs’ accuracy in detecting coherent motion only at very low duration values, revealing the efficacy of local integration mechanisms. Density impacted on dogs’ accuracy in a linear fashion, indicating less efficient global integration. There was limited evidence of improvement in the re-assessment but, with an average threshold at re-assessment of 29%, dogs’ ability to detect coherent motion remains much poorer than that of humans. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background Spinal walking ( SW) is described as the acquisition of an involuntary motor function in paraplegic dogs and cats without pain perception affected by a thoracolumbar lesion. Whereas spinal locomotion is well described in cats that underwent training trials after experimental spinal cord resection, less consistent information is available for dogs. Hypothesis Paraplegic dogs affected by a thoracolumbar complete spinal cord lesion undergoing intensive physical rehabilitation could acquire an autonomous SW gait under field conditions. Animals Eighty-one acute paraplegic thoracolumbar dogs without pelvic limb pain perception. Methods Retrospective study of medical records of dogs selected for intensive rehabilitation treatment in paraplegic dogs with absence of pain perception on admission and during the whole treatment. Binary regression and multivariate logistic regression were used to analyze potential associations with the development of SW. Results Autonomous SW was achieved in 48 dogs (59%). Median time to achieve SW was of 75.5 days (range: 16-350 days). On univariate analysis, SW gait was associated with younger age ( P = .002) and early start of physiotherapy ( P = .024). Multivariate logistic regression showed that younger age (≤60 months) and lightweight (≤7.8 kg) were positively associated with development of SW ( P = .012 and P < .001, respectively). BCS, full-time hospitalization, and type and site of the lesion were not significantly associated with development of SW. Conclusions Dogs with irreversible thoracolumbar lesion undergoing intensive physiotherapic treatment can acquire SW. Younger age and lightweight are positively associated with the development of SW gait. [ABSTRACT FROM AUTHOR]

The broad diversity inmorphology and geographic distribution of the 35 free-rangingmembers of the familyCanidae is only rivaled by that of the domesticated dog, Canis lupus familiaris. Considered to be among nature's most elite endurance athletes, both domestic and wild canids provide a unique opportunity to examine the variability in mammalian aerobic exercise performance and energy expenditure. To determine the potential effects of domestication and selective breeding on locomotor gait and economy in canids, we measured the kinematics andmass-specificmetabolismof three large (>20 kg) dog breed groups (northern breeds, retrievers and hounds) of varying morphological and genomic relatedness to their shared progenitor, the gray wolf. By measuring all individualsmoving in preferred steady-state gaits along a level transect and on a treadmill, we found distinct biomechanical, kinematic and energetic patterns for each breed group. While all groups exhibitedreducedtotal cost of transport (COT)at faster speeds, the total COT and net COT during trotting and galloping were significantly lower for northern breed dogs (3.0 and 2.1 J kg-1m-1, respectively) relative to hound(4.2and 3.4 J kg-1m-1, respectively)and retrieverdogs(3.8and 3.0 J kg-1 m-1, respectively) of comparable mass. Similarly, northern breeds expended less energy per stride (3.5 J kg-1 stride-1) than hounds or retrievers (5.0 and 4.0 J kg-1 stride-1, respectively). These results suggest that, in addition to their close genetic andmorphological ties to gray wolves, northern breed dogs have retained highly cursorial kinematic and physiological traits that promote economical movement across the landscape. [ABSTRACT FROM AUTHOR]

A 4 years old mongrel stray bitch, weighing 16kg was submitted to physical examination to demonstrated inability of locomotion with the pelvic limbs. Extradural spinal cord compression was observed in myelotomography of the thoracolumbar segment. The patient was submitted to exploratory hemilaminectomy of T13-L1 and L1-L2, in an attempt to decompress the medullar segments. During the surgery was observed one adult parasite, identified as Dioctophyma renale, located in the extradural space and causing spinal cord compression. The patient was submitted to postoperative physical therapy, presenting clinical improvement 15 days after surgery, remaining on prone position and able to move the pelvic limbs, but not yet able to walk unassisted. It started walking naturally 60 days after the surgery. With the present clinical report, the erratic migration of the parasite Dioctophyma renale should be added to the list of differential diagnoses for patients with paraparesis and extramedullary lesion pattern, especially in endemic areas. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate a simplified method of walking track analysis to assess treatment outcome in canine spinal cord injury. Measurements of stride length (SL) and base of support (BS) were made using a ‘finger painting’ technique for footprint analysis in all limbs of 20 normal dogs and 27 dogs with 28 episodes of acute thoracolumbar spinal cord injury (SCI) caused by spontaneous intervertebral disc extrusion. Measurements were determined at three separate time points in normal dogs and on days 3, 10 and 30 following decompressive surgery in dogs with SCI. Values for SL, BS and coefficient of variance (COV) for each parameter were compared between groups at each time point. Mean SL was significantly shorter in all four limbs of SCI-affected dogs at days 3, 10, and 30 compared to normal dogs. SL gradually increased toward normal in the 30 days following surgery. As measured by this technique, the COV-SL was significantly higher in SCI-affected dogs than normal dogs in both thoracic limbs (TL) and pelvic limbs (PL) only at day 3 after surgery. BS-TL was significantly wider in SCI-affected dogs at days 3, 10 and 30 following surgery compared to normal dogs. These findings support the use of footprint parameters to compare locomotor differences between normal and SCI-affected dogs, and to assess recovery from SCI. Additionally, our results underscore important changes in TL locomotion in thoracolumbar SCI-affected dogs. [ABSTRACT FROM AUTHOR]

Background: A prime concern of the gait analysis in a heterogeneous group of dogs is the potential influence of factors such as individual body size, body mass, type of gait, and velocity. Thus, this study aimed to evaluate in a heterogeneous group of dogs a possible correlation of the stride frequency with kinetic and temporospatial variables, as well as the percentage of body weight distribution (%BWD), and compare symmetry index (SI) between trotting and walking dogs. Twenty-nine clinically healthy dogs moving in a controlled velocity were used. The dogs were organized into two groups based on duty factor. Group 1 comprised 15 walking dogs, aged from 9 months to 8 years and weighing about 22.3 kg. Group 2 had 14 trotting dogs, aged from 1 to 6 years and weighing about 6.5 kg. The kinetic data and temporospatial parameters were obtained using a pressure-sensing walkway. The velocity was 0.9-1.1 m/s. The peak vertical force (PVF), vertical impulse (VI), gait cycle time, stance time, swing time, stride length, and percentages of body weight distribution among the four limbs were determined. For each variable, the SIs were calculated. Pearson's coefficient was used to evaluate correlation between stride frequency and other variables, initially in each group and after including all animals. Results: Except for the %BWD (approximately 60 % for the forelimbs and 40 % for the hind limbs), all other parameters differed between groups. Considering each Group individually a strong correlation was observed for most of the temporospatial parameters, but no significant correlation occurred between stride frequency and PVF, and stride frequency and %BWD. However, including all dogs a strong correlation was observed in all temporospatial parameters, and moderate correlation between stride frequency and VI, and weak correlation between stride frequency and PVF. There was no correlation between stride frequency and %BWD. Groups 1 and 2 did not differ statistically in SIs. Conclusions: In a heterogeneous group of dogs conducted at a controlled velocity, the %BWD and most of SIs presented low variability. However, %BWD seems to be the most accurate, since factors such as the magnitude of the variables may influence the SIs inducing wrong interpretation. Based on results obtained from correlations, the standardization of stride frequency could be an alternative to minimize the variability of temporospatial parameters. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate dogs with pelvic fractures and treated conservatively during locomotion on a pressure-sensing walkway. The hypothesis was that dogs may present changes in kinetic and temporospatial parameters because of the fractures, which may interfere with the symmetry index. Thirty dogs were selected and divided into two groups: Group 1–healthy group (n = 15) and Group 2–conservatively treated group (n = 15). The dogs were of similar body size. The body weight distribution percentages and symmetry indices of the peak vertical force, vertical impulse, stance time, swing time, percentage of stance time, and percentage of swing time of the hind limbs were evaluated. Results: In Group 2, the time interval between fracture occurrence and patient evaluation was between 4 and 87 months (mean of 20 months). Four dogs had lower percentage of body weight distribution on one of the hind limbs while three dogs had greater weight distributed toward both hind limbs. Four of these dogs had alterations in the temporospatial and/or kinetic symmetry indices. Conclusions: Dogs with pelvic fractures treated conservatively may present changes in percentage of body weight distribution and symmetry indices of the kinetic and temporospatial parameters. The conservative treatment can cause persistent abnormal gait. [ABSTRACT FROM AUTHOR]

Alterations in muscle recruitment are key to the functional plasticity of the mammalian locomotor system. One particularly challenging situation quadrupeds may face is when the functionality of a limb is reduced or lost. To better understand how mammals manage in such situations and which muscular adaptations they exhibit when locomoting on three legs, we recorded the activity patterns of two limb and one back extensor muscle in nine dogs using surface electromyography. We compared the timing and the level of recruitment before and after the loss of a hindlimb was simulated. Both the intensity and the timing of the activity changed significantly in the m. vastus lateralis of the remaining hindlimb, consistent with this limb bearing a greater proportion of the body weight as well as with previously reported kinematic changes. In accordance with the greater body weight supported by the forelimbs, the m. triceps brachii showed first and foremost an increased level of excitation. The very asymmetrical changes in the timing and the level of activity in the m. longissimus dorsi reflects the highly asymmetrical functional requirements imposed on the trunk and the pelvis when one hindlimb is no longer involved in the production of locomotor work while the other hindlimb partially compensates the loss. Integration of our electromyographical findings with kinetic and kinematic results illustrates that dogs exhibited a well-coordinated response to the functional requirements of tripedalism and underlines the importance of moment-to-moment modulation in muscular recruitment for the functional plasticity of the mammalian locomotor system. J. Exp. Zool. 323A: 506-515, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The rich repertoire of locomotor behaviors in quadrupedal animals requires flexible inter-limb and inter-segmental coordination. Here we studied the kinematic coordination of different gaits (walk, trot, gallop, and swim) of six dogs (Canis lupus familiaris) and, in particular, the planar covariation of limb segment elevation angles. The results showed significant variations in the relative duration of rearward limb movement, amplitude of angular motion, and inter-limb coordination, with gait patterns ranging from a lateral sequence of footfalls during walking to a diagonal sequence in swimming. Despite these differences, the planar law of inter-segmental coordination was maintained across different gaits in both forelimbs and hindlimbs. Notably, phase relationships and orientation of the covariation plane were highly limb specific, consistent with the functional differences in their neural control. Factor analysis of published muscle activity data also demonstrated differences in the characteristic timing of basic activation patterns of the forelimbs and hindlimbs. Overall, the results demonstrate that the planar covariation of inter-segmental coordination has emerged for both fore- and hindlimbs and all gaits, although in a limb-specific manner. [ABSTRACT FROM AUTHOR]

Limb amputation often represents the only treatment option for canine patients with certain diseases or injuries of the appendicular system. Previous studies have investigated adaptations to tripedal locomotion in dogs but there is a lack of understanding of biomechanical compensatory mechanisms. This study evaluated the kinematic differences between quadrupedal and tripedal locomotion in nine healthy dogs running on a treadmill. The loss of the right pelvic limb was simulated using an Ehmer sling. Kinematic gait analysis included spatio-temporal comparisons of limb, joint and segment angles of the remaining pelvic and both thoracic limbs. The following key parameters were compared between quadrupedal and tripedal conditions: angles at touch-down and lift-off, minimum and maximum joint angles, plus range of motion. Significant differences in angular excursion were identified in several joints of each limb during both stance and swing phases. The most pronounced differences concerned the remaining pelvic limb, followed by the contralateral thoracic limb and, to a lesser degree, the ipsilateral thoracic limb. The thoracic limbs were, in general, more retracted, consistent with pelvic limb unloading and previous observations of bodyweight re-distribution in amputees. Proximal limb segments showed more distinct changes than distal ones. Particularly, the persistently greater anteversion of the pelvis probably affects the axial system. Overall, tripedal locomotion requires concerted kinematic adjustments of both the appendicular and axial systems, and consequently preventive, therapeutic and rehabilitative care of canine amputees should involve the whole musculoskeletal apparatus. [ABSTRACT FROM AUTHOR]

Canine agility is a rapidly growing sport in the UK. However, there is a paucity of scientific research examining jump kinematics and associated health and welfare implications of the discipline. The aim of this research was to examine differences in jump kinematics and apparent joint angulation of large (>431 mm at the withers) agility dogs ( n  = 54), when the distance between hurdles was altered (3.6 m, 4 m and 5 m apart) and to determine how level of skill impacted upon jump kinematics. Significant differences were observed for both the take-off ( P  <   0.001) and landing distances ( P  <   0.001) between the 3.6 m, 4 m and 5 m distances. Further differences were observed when level of skill was controlled for; take-off ( F [3,55] = 5.686, P  = 0.002) and landing ( F [3,55] = 7.552, P  <   0.001) distances differed at the 3.6 m distance, as did the take-off distance at the 4 m hurdle distance ( F [3,50] = 6.168, P  = 0.001). Take-off and landing speeds differed for hurdle distances ( P  <   0.001) and level of skill ( P  <   0.001). There were significant differences in apparent neck angle during take-off and landing ( P  <   0.001), lumbar spine angles during take-off, bascule and landing ( P  <   0.01), and in shoulder angles during the bascule phase ( P  <   0.05). The results indicate that agility dogs alter their jumping patterns to accommodate the spacing between hurdles, which ultimately may impact long term health and welfare due to altered kinematics. [ABSTRACT FROM AUTHOR]

Factors that contribute to variance in ground reaction forces (GRF) include dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population of clinically normal dogs, it was hypothesized that the dog subject effect would account for the majority of variance in peak vertical force (PVF) and vertical impulse (VI) at a trotting gait, and that narrow velocity ranges would be associated with less variance. Data from 20 normal dogs were obtained. Each dog was trotted across a force platform at its habitual velocity, with controlled acceleration (±0.5 m/s²). Variance effects from 12 trotting velocity ranges were examined using repeated-measures analysis-of-covariance. Significance was set at P< 0.05. Mean dog bodyweight was 28.4 ± 7.4 kg. Individual dog and velocity significantly affected PVF and VI for thoracic and pelvic limbs (P< 0.001). Trial number significantly affected thoracic limb PVF (P< 0.001). Limb (left or right) significantly affected thoracic limb VI (P=0.02). The magnitude of variance effects from largest to smallest was dog, velocity, trial repetition, and limb. Velocity ranges of 1.5-2.0 m/s, 1.8-2.2 m/s, and 1.9-2.2 m/s were associated with low variance and no significant effects on thoracic or pelvic limb PVF and VI. A combination of these ranges, 1.5-2.2 m/s, captured a large percentage of trials per dog (84.2 ± 21.4%) with no significant effects on thoracic or pelvic limb PVF or VI. It was concluded that wider velocity ranges facilitate capture of valid trials with little to no effect on GRF in normal trotting dogs. This concept is important for clinical trial design. [ABSTRACT FROM AUTHOR]

Quadrupedal locomotion is the result of complex interactions between biomechanical and neural systems. During steady gaits, both systems are in stable states. When the animal changes its speed, transitions between gaits can occur in which the different coordination parameters are dissociated. Consequently, transitions are the periods where it is possible to detect and identify those parameters involved in the mechanical or neural control of locomotion. We studied interlimb coordination using a sequential method (antero-posterior sequence) to measure the footfall patterns of dogs when accelerating and decelerating from 1.5ms-1 to more than 6ms-1 and back. We obtained 383 transitions between all the symmetrical and asymmetrical gaits used by the dogs. Analysis of the interlimb coordination modifications and of each foot parameter showed that mechanics drive the stance phase whereas coordination is controlled during the swing phase. Furthermore, comparison of the transition patterns between all gaits reveals the modular organization of locomotion: a pectoral module coordinates the two forelimbs, a pelvic module coordinates the two hindlimbs and an axial module coordinates the two pairs of limbs and the trunk motion. The three modules cooperate to give rise to a template of stable interlimb coordination pattern, such as walk, trot or gallop. [ABSTRACT FROM AUTHOR]

Objective--To compare overground and treadmill-based gaits of dogs. Animals--5 clinically normal adult mixed-breed dogs. Procedures--To obtain dynamic gait data, 30 retroreflective markers were affixed bilaterally to specific regions of the hind limbs and pelvis of each dog. For each dog, 3-D joint motion data (sagittal [flexion and extension], transverse [internal and external rotation], and frontal [abduction and adduction] planes of motion) for the hip, femorotibial, and tarsal joints were acquired during walking and trotting through a calibrated testing space overground or on a treadmill. Comparison of data was performed via generalized indicator function analysis and Fourier analysis. Results--Both overground and treadmill-based gaits produced similar waveforms in all planes of motion. Fourier analysis revealed no difference between overground and treadmill- based gaits in the sagittal plane of motion; however, small differences were detected between overground and treadmill-based gaits in the other 2 planes of motion. Additionally, femorotibial joint motion during walking did not differ among planes of motion. Generalized indicator function analysis was able to detect differences between overground and treadmill-based gait waveforms in all planes of motion for all joints during walking and trotting. Conclusions and Clinical Relevance--In dogs, overground and treadmill-based gaits produced similar waveform shapes. Of the 3 planes of motion evaluated, only sagittal plane kinematic gait data were unaffected by mode of ambulation as determined via Fourier analysis. Sagittal kinematic gait data collected from dogs during overground or treadmill-based ambulation were comparable. However, analysis methods may affect data comparisons. [ABSTRACT FROM AUTHOR]

Abstract: Dogs exhibit biorhythms like diurnal sleep/wake and rest/activity behavior patterns with circadian rhythmicity and, similar to other mammalian species, show age-dependent changes in activity rhythms. This study sought to further characterize night/day locomotor activity patterns in adult dogs of various ages, and to examine the effect of feeding frequency (once vs. twice). Three groups (early adults [EA], 1.5-4.5 years; late adults [LA], 7-9 years; senior, 11-14 years) of beagles (N = 48) wore the Actiwatch activity monitoring system for 3 days while housed indoors with 12-hour light/dark schedule. Activity recording devices were used to collect actigraphy data when dogs were on a once- or twice-daily feeding regimen. All dogs demonstrated a circadian activity pattern with high levels of daytime activity and low levels of nighttime activity. The main effect of age differed for both daytime (P < 0.0001) and nighttime (P = 0.002) activity counts. Daytime activity in senior dogs was 17% and 42% lower compared with LA and EA dogs, respectively. With nighttime activity, both LA and seniors had significantly lower counts compared with the EA. Compared to once-daily feeding, twice-daily feeding significantly increased night activity, night/day activity ratio, and activity counts 60 minutes before the light phase across all 3 age-groups. This study provides a comprehensive characterization of age-related changes in locomotor behavior patterns in dogs and uniquely demonstrates that frequency of feeding can influence nighttime activity levels, which is partially associated with level of prelight onset of activity. [Copyright &y& Elsevier]

A recent survey reported an increased risk of injury in dogs participating in agility, a competitive canine sport involving different jumping activities. The aim of this study was to quantify the kinetic parameters during jump landing for commonly used obstacle types. It was hypothesised that with increasing obstacle height, the vertical force and vertical and accelerative horizontal impulse will increase as a result of a lengthened aerial phase, a more acute landing angle and the need to convert potential into forwards kinetic energy. Simultaneous kinetic and kinematic data were recorded from 11 competition agility dogs jumping over obstacle combinations of different height and inter-obstacle distance. Speed and landing angle of the second of the two consecutive jumps were successfully controlled by obstacle height and distance between obstacles. Statistical analysis showed differences between obstacles for peak vertical force, vertical impulse and accelerative horizontal impulse (increasing values with more acute landing angles). Extremely high peak vertical force was observed in the forelimbs (4.5 times bodyweight) when landing from a hurdle jump at high speed. Further detailed studies into the consequences for internal limb structures are warranted in order to clarify how this might be related to injury. [ABSTRACT FROM AUTHOR]

Wearable technologies impact on human performance monitoring. Technology designed for human monitoring was used as a proof of concept study to determine the effectiveness of monitoring physical activity of two different sized dogs. The device found significant step count differences with the smaller dog having greater step count. This was confirmed from step counts taken from an associated video recording. Therefore the study showed that a wearable device could measure step counts of dogs. Meaning that users can monitor their own physical activity or that of their pet with the same device. [ABSTRACT FROM AUTHOR]