A validation study to analyze the reliability of center of pressure data in static posturography in dogs

Introduction

Center of pressure (COP) parameters are frequently assessed to analyze movement disorders in humans and animals. Methodological discrepancies are a major concern when evaluating conflicting study results. This study aimed to assess the inter-observer reliability and test-retest reliability of body COP parameters including mediolateral and craniocaudal sway, total length, average speed and support surface in healthy dogs during quiet standing on a pressure plate. Additionally, it sought to determine the minimum number of trials and the shortest duration necessary for accurate COP assessment.

Materials and methods

Twelve clinically healthy dogs underwent three repeated trials, which were analyzed by three independent observers to evaluate inter-observer reliability. Test-retest reliability was assessed across the three trials per dog, each lasting 20 seconds (s). Selected 20 s measurements were analyzed in six different ways: 1 × 20 s, 1 × 15 s, 2 × 10 s, 4 × 5 s, 10 × 2 s, and 20 × 1 s.

Results

Results demonstrated excellent inter-observer reliability (ICC ≥ 0.93) for all COP parameters. However, only 5 s, 10 s, and 15 s measurements achieved the reliability threshold (ICC ≥ 0.60) for all evaluated parameters.

Discussion

The shortest repeatable durations were obtained from either two 5 s measurements or a single 10 s measurement. Most importantly, statistically significant differences were observed between the different measurement durations, which underlines the need to standardize measurement times in COP analysis. The results of this study aid scientists in implementing standardized methods, thereby easing comparisons across studies and enhancing the reliability and validity of research findings in veterinary medicine.

Effect of Vision and Surface Slope on Postural Sway in Healthy Adults: A Prospective Cohort Study

Postural stability requires an interaction between cognitive, perceptual, sensory, and motor functions. Thus, impairment in any of these systems may affect postural balance. This study assessed the effect of visual input and surface slope on postural stability. The study was conducted on healthy participants, 11 females and 11 males who were 24-34 years of age. They were asked to perform still upright bipedal standing on flat and +/-20° sloped surfaces with eyes open (EO) and closed (EC). Six center of pressure (COP) parameters were measured by posturography. A significant relationship was observed between COP parameters, standing conditions, and body mass index. Gender had no significant effect on the COP. The loss of visual input within each standing condition did not affect the COP parameters. In contrast, differences were observed between standing on a flat surface and uphill with EC and between standing on a flat surface and downhill with EC and EO. When the participants were standing on inclined surfaces, the loss of vision significantly increased the postural instability. Young healthy adults demonstrated the greatest difficulty in standing uphill with EC. This was followed by standing downhill with EC and standing downhill with EO.

External mechanical perturbations challenge postural stability in dogs

This study aimed to explore the effect of external mechanical perturbations on postural stability (PS) in dogs using the body center of pressure (COP). Thirteen sound adult dogs were included in this study. PS was tested during quiet standing on a pressure measurement plate. The conditions included a standard standing measurement and external mechanical perturbations conducted using six settings on a motorized training platform with different intensities of speed and amplitude. Measurement conditions were compared using linear mixed-effects models, followed by multiple comparisons using Sidak's alpha correction procedure. Compared with the standing measurement, external mechanical perturbations resulted in a significant increase in almost all COP parameters, indicating a challenge for the PS. Furthermore, an increase in amplitude had a greater effect than an increase in speed, whereas the combination of the highest intensities of amplitude and speed was not well tolerated by the dogs. The mediolateral COP displacement was significantly greater than the craniocaudal COP displacement during standing measurement and conditions with a small amplitude, whereas no significant difference was observed during settings with an increased amplitude. To the best of our knowledge, this is the first study to demonstrate the effects of a balance training device in dogs. Therefore, the intensity of the training programs on motorized platforms or similar devices can be controlled by the wobbling amplitude of the platform.

Vertical ground reaction forces, paw pressure distribution, and center of pressure during heelwork in working dogs competing in obedience

Heelwork walking is a command that competitive obedience and working dogs are trained to perform. Unlike other canine sports, the research for competitive obedience sport is limited and no research regarding biomechanical gait adaptions during heelwork walking has been published. The aim of the study was to investigate the changes in vertical ground reaction forces, paw pressure distribution (PPD), and center of pressure (COP) of Belgian Malinois during heelwork walking. Ten healthy Belgian Malinois were included in the study. The dogs walked first without heeling (normal walk) and then while heeling on a pressure platform. The comparison between normal and heelwork walking was performed using mixed-effects models. Post-hoc analyses were performed using Sidak's alpha correction procedure. During heelwork walking, a significant decrease in the vertical impulse and stance phase duration (SPD) and a significant increase in the craniocaudal index and speed of COP was observed in the forelimbs compared to normal walking. At the hindlimbs, a significant increase in vertical impulse and SPD was observed during heelwork walking. Regarding PPD, a significant decrease of vertical impulse was observed at the cranial quadrants of the right forelimb and craniolateral quadrant of the left forelimb during heelwork. The area was significantly decreased at the craniolateral quadrant of the left forelimb and the time for the peak vertical force was prolonged significantly at the caudal quadrants of the right forelimb during heelwork walking. The vertical impulse was significantly increased in all quadrants of the hindlimbs except the craniolateral quadrant of the left hindlimb. The effect of these changes on the musculoskeletal system of working dogs should be investigated in further studies, using electromyography and kinematic analysis.

Center of pressure and ground reaction forces in Labrador and Golden Retrievers with and without hip dysplasia at 4, 8, and 12 months of age

Canine hip dysplasia (CHD) is a common orthopedic disease. Owing to the importance of CHD in affected dogs, both clinically and for their use in breeding or work, increasing attention is being given to early diagnosis. Therefore, early clinical and radiological examination of young animals is increasingly in demand, whereas common CHD screening according to the Fédération Cynologique Internationale (FCI) is usually performed at the age of 12 months or even older in Europe. One way to objectively evaluate gait pattern is to measure the ground reaction forces (GRFs) and center of pressure (COP). In this study, we used a pressure plate to evaluate the GRF and COP parameters for 32 Labrador Retrievers and 17 Golden Retrievers at 4, 8, and 12 months of age. The dogs also underwent radiological examination of the hip joints following the FCI rules at the age of at least 12 months, which were grouped as sound (FCI grade A or B) and diseased (FCI grade C or worse). The results revealed significantly higher COP values in both breeds in the diseased limb groups at any measurement point during walking, with the most pronounced results obtained at 8 months of age. Furthermore, COP values during walking were significantly higher at 4 months than at 8 and 12 months in both the sound and diseased limb groups, indicating an increased stability of the gait pattern. Except for COP-Speed, the values of all COP parameters were higher during walking than during trotting at 4 months of age (i.e., COP-Speed was higher when trotting), indicating that the 4-beat gait in walk is more difficult to control for puppies than the 2-beat gait in trot. Overall, our results support the early evaluation of CHD in growing animals using non-invasive methods.

Amendments suggested for zoo medical research strategies with focus on the D-A-CH region

OBJECTIVE

Scientific exploration of zoo animals is one of the main missions of modern zoos. As scientific achievements are best reflected within scientific literature, we screened appropriate literature search outcomes from the 5 highest ranked zoos in the D-A-CH region (Germany-Austria-Switzerland) in order to deduce suggestions for optimizations of future research strategies.

MATERIAL AND METHODS

Literature search was done by entering "Zoo Vienna", "Tiergarten Schönbrunn", "Zoo Berlin", "Tiergarten Berlin", "Tierpark Hellabrunn", "Tierpark Hagenbeck", and "Zoo Zurich" on PubMed and Scopus for the period 2000-2020. These 5 European zoos were chosen due to their broad public recognition and international importance. Inclusion criterion for the literature list was the description/mentioning of analysed animals or samples with a clear affiliation to the respective zoo in the materials and methods or acknowledgements sections. Search hits were then allocated to the following 7 areas: animal nutrition, biology, ethology, infectiology, reproduction, phylogenetics, and clinical medicine. Also, portions of higher animal taxa (and species, if appropriate) were recorded.

RESULTS AND CONCLUSIONS

A total of 142 papers has been published. Mammals, especially large ones, were clearly over-represented in literature with 2 thirds of analysed papers dealing with them. Sauropsids (birds and reptiles) were treated in 28 % and non-amniotic vertebrates (amphibians and fish) as well as invertebrates in only 3 % each. This apportionment is in no relation to the species numbers of the respective higher animal taxa. The predominating research areas (covered by approximately 75 % of papers) were ethological studies, followed by papers on infectious diseases, and finally papers on biology with morphological, physiological, and molecular biological themes. Research on reproductive biology/medicine, which is considered to be of tremendous importance for the establishment of ex-situ populations and thus for the conservation of endangered species, has been covered by only 6 % of papers. Future research should more intensely keep an eye on that discipline, especially in non-mammalian vertebrates.