Looks like a fun project.
I'd suggest animating your dog to have a normal running/walking speed, getting it to look good, and then stretching the timeline later. You can adjust the FPS on Ziva's solver too when you get to that. It'll be easier to critique your animation and tune your simulation this way.
Here's some notes on your muscles. You're getting some large voids opening up, and the brachiocephalicus/brachioradialis could have better silhouettes
I think you might benefit from doing another modeling pass on the muscles too. Here's some other dog models for you to get a feel for the direction.