Working dogs often wear service vests. The function of these vests includes use in transportation of supplies and equipment, cooling of the dog, protection of the dog, or providing a harness for lifting of the dog. Although the uses of canine vests are diverse, limited information is available on how the design of these vests affects the general body movement and, more specifically, the movement of the trunk of a dog. There is also a lack of information describing how movement of the truncal region impacts the mechanical energy required of dogs during various gaits. Furthermore, few data exist regarding the relationship of canine truncal kinematics to gait patterns. A better comprehension of the relationship between truncal rotation and gait patterns is required if the overall impact of service vests on the kinematics of dogs is to be understood.
One model to quantify movement of the back of dogs involves creating vectors between vertebrae and then calculating rotation of one vector relative to another during a gait.1,2 However, movement of the vertebrae does not necessarily reflect trunk rotation. The relationship between trunk rotation and gait has been measured in horses. Results of these studies3,4 suggest that truncal rotation can have a major impact on animal gait. Investigators in 1 study3 used inertial sensors to track a horse's center of mass, which then defined the pattern of trunk rotation during a gait; their findings suggested a relationship between truncal rotation and forelimb stance phase. Investigators in another study4 used a cinematography technique to monitor the position of a horse's center of mass during turning and to quantify trunk rotation relative to the vertebral column.
The overall objective of the study reported here was to develop a 3-D kinematic model that could be used to measure truncal motion in dogs and assess changes in truncal motion in dogs when wearing each of 2 service vests. To achieve this objective, the first goal was to identify anatomic landmarks that could be used to establish vectors that would be acceptable positional reference points for quantifying the rotation of a dog's trunk during a gait cycle. Acceptable landmarks were defined as those that produced a vector or a set of vectors with magnitudes that remained nearly constant during the entire gait cycle. These acceptable landmarks would provide a vector system needed to create an LCS necessary to quantify rotation of a dog's trunk. Four hypotheses were tested for the first goal:
• Hypothesis 1: relative to the left iliac crest, the magnitude of vectors connecting vertebrae T1 and T13 will not remain constant as a dog walks and trots on a treadmill.
• Hypothesis 2: relative to the right iliac crest, the magnitude of vectors connecting vertebrae T1 and T13 will not remain constant as a dog walks and trots on a treadmill.
• Hypothesis 3: relative to the dorsal aspect of the left scapula, the magnitude of vectors connecting vertebrae T1 and T13 will not remain constant as a dog walks and trots on a treadmill.
• Hypothesis 4: relative to the dorsal aspect of the right scapula, the magnitude of vectors connecting vertebrae T1 and T13 will not remain constant as a dog walks and trots on a treadmill.
The second goal of the study reported here was to use the data from the first goal to assess changes in truncal motion in dogs when wearing each of 2 service vests. For this second goal, hypothesis 5 was tested: rotation of the trunk for a dog wearing a service vest will not be equal to the rotation of the trunk for a dog not wearing a service vest.
We anticipated that the obtained data would provide insights into the methods used to assess the impact that wearing a service vest will have on gait patterns of dogs. Data collection would be conducted over multiple days for each dog, which would lead to the final hypothesis (hypothesis 6): for each dog, rotation of the trunk will remain the same throughout all days of testing.
The authors declare there were no conflicts of interest.
Anatomic thorax coordinate
Local coordinate system
Range of motion
Large DogTread, PetZen Products, Ogden, Utah.
Eagle Industries, Virginia Beach, Va.
T-series, Vicon, Lake Forest, Calif.
Peak Motus, version 9, Vicon, Lake Forest, Calif.
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