Do a forum search for a user name - ‘waylow’. He rigged a horse and a dog and released them to everyone. They are also on blend swap as well. Both these characters used a double IK setup on the back legs. With this setup, the hind leg had a foot controller, and 2 pole targets, on for the regular knee, and one for the back joint above the foot. This leg setup worked well, and you could look into how he rigged them to get ideas how to do this.
Please note that these characters used python scripts for the UI fk/ik switches and so on. They are old characters, circa blender 2.55 or so, so the scripts are out of date. They will need updating to get them to work with the current version of blender. If you go this route and want the scripts updated, let me know and I can fix them up for you.
edit: Here’s a video of the dog character, animated in blender 2.49…