Most dogs appear to adapt well to the removal of a thoracic limb1,2; appropriate adaptation may be influenced by conscientious presurgical selection of patients for amputation. Anecdotally, some dogs have difficulties with locomotion following thoracic limb amputation. In 1 survey,3 some clients indicated that their dogs were not able to return to normal locomotive function, even after a 4-week adaptation period following amputation. It has been hypothesized that age, body weight, and breed may affect a dog's functionality after amputation,3–8 although body weight has not been found to be a factor that contributes to subsequent disability.3 Additionally, owner surveys1,2 encompassing dogs of a wide variety of ages and breeds do not indicate that these factors negatively impact the ability of a dog to adapt to the loss of a thoracic limb. On the basis of this information, other factors related to gait are thought to contribute to a decrease in mobility and activities in some canine amputees.
It is important that clinicians and researchers understand the compensatory changes in gait for dogs that have undergone thoracic limb amputation.1,3 Currently, information about compensatory gait strategies in thoracic limb amputees is limited to kinetic data evaluations of GRF, impulse duration, and stance duration in 5 amputee dogs during walking.9 In comparison with results for control dogs, thoracic limb amputees distribute an additional 17% of body weight to the remaining thoracic limb and an additional 13% of body weight to the pelvic limbs during the stance phase while maintaining similar peak vertical GRFs over a shorter stance duration.9 Amputees also compensate for the loss of a thoracic limb by increasing the braking duration of the remaining thoracic limb instead of distributing more of the braking demands to the pelvic limbs.9
A need exists to better understand the compensatory mechanisms that alter loading and joint motion of the remaining limbs in amputee dogs. Although the gait has been evaluated in amputee dogs during walking,9 the authors are not aware of any prior gait analysis of amputees during trotting, a motion whereby limbs may have higher GRFs and possible periods of support on a single limb. The GRF analysis provides a limited understanding of the gait in amputees; therefore, kinematic analysis of the limbs and vertebral column is needed to fully assess potential strategies for musculoskeletal compensation. Any alteration to normal limb kinematics can impact the distribution of joint forces,10–12 which can lead to gross instability, muscle dysfunction, pain, and a decrease in ROM of joints. There may be increases in inflammation, impaired synthesis of cartilage, and cartilage degradation11,12 within the joint of interest, which possibly could also affect adjacent joints.13 Evidence of altered joint angles and ROMs combined with GRF analysis will help to identify joint loading patterns and compensatory strategies in the gait of amputee dogs.10–12 Altered limb kinematics and increased motion of the vertebral column may also lead to degenerative changes and altered muscular control of the remaining limbs.11,12,14
The extent of compensatory strategies in the gait of amputee dogs is unknown. The purpose of the study reported here was to objectively compare differences in gait between dogs that underwent thoracic limb amputation and a clinically relevant cohort of quadruped control dogs that had orthopedic, neurologic, or other related comorbidities similar to those of the amputee dogs, thus reflecting patient conditions in a clinical environment.
Cervicothoracic vertebral region
Ground reaction force
Lumbosacral vertebral region
Range of motion
Thoracolumbar vertebral region
Roberts indoor/outdoor double-sided carpet tape, QEP, Boca Raton, Fla.
Motus 9.0, Vicon Motion Systems Inc, Centennial, Colo.
Model BP400600-1000 force platforms, AMTI Inc, Watertown, Mass.
Model OR6-5-1000 force platforms, AMTI Inc, Watertown, Mass.
Dinion, Bosch Security Systems Inc, Fairport, NY.
MEK-92-PAD, Mekontrol Inc, Richardson, Tex.
Matlab, R2010a, MathWorks, Natick, Mass.
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