You could do it fairly easily. You could enlist the help of a local metal fabricator to get an ‘L’ shaped bracket to fit a harness like the one here: http://katok9gear.mybigcommerce.com/atilla-leather-dog-harness/ Then you could use the tripod mount on your 7D Mk II, to mount the camera to the bracket.
Put a 50 mm f/1.8 lens on it, set it to auto focus. Set the 7D to ‘P’ mode. In the menus, choose Interval Timer under the fourth square of the left camera icon. Set it enabled, set a suitable interval time, perhaps a minute or two, then set the number of shots to 99. Mount the camera on the dog, depress the shutter release all the way and let the dog go.
Turning off the camera will stop interval exposures if the dog comes back before the camera gets through the 99 shots.