Kim,
leveling the image is easy in Photoshop so that's no problem. If you shot jpeg, simply use the ruler tool to trace the horizon line and then go to Image/Rotate/Arbitrary and it will be automatically set to give you a level horizon.

Also, if you shot RAW, you can level it in ACR.

And, if you shot RAW, you can recover the edges by saving it as a DNG and dropping it into the DNG Recover Edges application. That will give you at least the right rear foot. The rest is a matter of cropping. Whether it's a good coursing image, I can't say. Not my game. But in the Agility Trials I've shot, folks expect the entire dog.

Jim