Yep, that's what the fusion does. It stabilizes the bone but at a great loss of flexibility depending upon the amount of hardware used. I have 4 of my cervical vertebra fused together and have very limited motion but I'm still here. I would imagine with as extensive an amount of hardware as Barbaro has, there will be a change to the gait but the body is kind of a neat thing in that other area's help to compensate for the loss of motion. As an example, my back vertebra have compensated for my loss by becoming more flexible.
You are so right about the body being able to compensate. I'm 59, played a few sports at a high level years ago, and had my share of injuries, even broke my ankle once back in '68. I have also seen, like you, how other parts of our bodies can compensate for the limitations of other parts.
Thanks for your replies, and I'm praying for this good horse to do well and live through this terrible injury.
And thanks to the great doctors.