Taken Bonnie out to Edale and Hebden Bridge (Pig, Pecket Well etc). She’s half lab, half collie. Happy to confirm that she destroys me on the descents. Have taken her to trail centres, but is more problematic as she gets too close to other riders.
I’d say you need to make sure that she knows to steer clear of the bike (start her on short rides, with little penalty for failure), that she is fit enough to follow whatever loop it is that you’re doing, that you take water with you (or plot a route with lots of trees/rivers) and that she has good recall as if you’re out in the country you’re bound to encounter sheep/cattle at some point.
I always try to plot routes that have long, slow uphills, followed by steep, techy descents (Edale and Hebden pretty much fit that bill); as that way there’s very little flat out riding that will properly knacker her out.
Highly recommended, my dog absolutely loves going out with the bike