MXR,

Jeffco also has the same leash laws for the most part. If your dog is off the leash and they attack another person, livestock, wildlife you can be held accountable.

you are responsible for your dogs actions it really doesn't matter where you are.

In AZ the dog can be legally shot for chasing livestock.

I am all for the dogs having a place to run loose, but just because you are on a forest trail doesn't mean you can do it legally.