Instrumented gait analysis to characterize pelvic limb ataxia in dogs

Musa Ahmed Alshehabat, Purdue University

Abstract

The broad objective of these studies was to develop objective techniques for gait analysis of individual dogs with gait impairment due to spinal cord injuries. A limitation of present canine gait analysis techniques is that they are focused on groups of dogs instead of individual dogs and that criterion to diagnose lameness or neurological impairment in dogs of all sizes and shapes do not exist. Therefore a series of studies was conducted, starting with two studies focused on the development of normal values for kinetic parameters for walking dogs, using a pressure sensing walkway. The final two studies were conducted to objectively characterize canine ataxia. In chapter 4, the hypothesis that in walking dogs Peak Vertical Force (PVF) can be described as a function of body weight was tested and accepted. The hypotheses that PVF normalized for bodyweight (%PVF) of thoracic and pelvic limbs respectively, and the dynamic weight distribution (%WD) among the four limbs is constant in dogs of different sizes was also tested. The PVF normalized for body weight (%PVF) was not constant across body weights but was inversely related to body weight. This indicates that the %PVF should not be used to compare the PVF from dogs with different body weight. The results of this study also suggested that the dynamic distribution of force among the four limbs (%WD) was constant and independent of body weight, velocity and gait. Thus %WD may be an excellent variable to compare dogs with different body weight. By calculating 95% confidence intervals, normal ranges were established for PVF, %WD and associated coefficients of variation and symmetry indices. These normal values may be used to diagnose lameness or neurological impairment in dogs of any size and shape. Another finding was that dogs under 10 kg body weight trot (duty factor < 0.5) instead of walk (duty factor ≥ 0.5) during self-selected velocity. This prompted the design of a study in small size dogs ambulating at a "comfortable" (trot) and "forced" (walk) walking gait (chapter 5). The results of this study demonstrated PVF differences between the two gaits, and also suggested that the %WD during the two gaits may be the same. Both studies also suggest that duty factor must be included as an integral part of a gait analysis to appropriately characterize a dog's gait. In chapters 6 and 7, ataxia was objectively characterized using instrumented gait analysis. In chapter 6, the hypothesis that ataxia in dogs suffering from cervical spinal cord injury may be characterized by an increase in coefficient of variation (%CV) of kinetic and kinematic parameters, a reduction of ground reaction forces, a reduced walking velocity was tested. It was demonstrated that dogs with cervical spinal cord injury (CSCI) have reduced PVF of thoracic limbs, increased variability of kinetic and kinematic variables, weight shifting from thoracic to pelvic limbs as evaluated by %WD, and a reduced walking velocity. In chapter 7, the hypothesis that recovery of ataxia is characterized by a gradual decrease in CV of kinetic and kinematic parameters, a gradual increase in ground reaction forces and walking velocity was evaluated in dogs recovering from thoracolumbar spinal cord injury (TLSCI). Dogs recovering from TLSCI often started with high variability of kinetic or kinematic variables which gradually decreased over the course of recovery. It was hard to make clear statements because of small number of dogs studies, and because dogs had different severity of neurological signs at the beginning of the study, were in different stages of recovery at the beginning of the study and probably had different rates of recovery. The results of the studies reported in chapter 6 and 7 also suggested that evaluation of joint angles may have limited value for the determination of ataxia. These studies collectively suggest that instrumented gait analysis may allow objective evaluation of ataxia in groups of dogs and individual dogs. Although the findings of these studies are very promising and encouraging for both diagnostic and treatment application, more work is needed before instrumented gait analysis can be used for routine evaluation of individual patients with neurologically impaired gait.

Degree

Ph.D.

Advisors

Breur, Purdue University.

Subject Area

Veterinary services

COinS