Hi there,
It would depend more on symptoms. If the dog is cold and deficient looking, with a weak pulse and lots of cramping types of issues, the then the Lower burner formula is more called for.
If the animal has more heat signs and isn't Kidney deficient, and their pulse feels more wiry, the the Middle Burner formula is more called for.
If the problem is manifesting as overt colitis, then you could team Xiao Chai Hu Tang with either one of them to try to address that
Steve