Thank you all for your posts. I think we'll start out with a divided yard and see how the dog does while supervised. Hopefully, they will become great friends!
Will the dog chase a ball or frisbee? If so, it'll probably chase a goat. If not, then prey drive is probably low enough to consider a trial run as a LGD...if you can handle an 'oops, guess that didn't work' situation that may involve an injury to a goat. St. Bernards are Molosser dogs, and thus very closely related to lots of other well-known guardian dogs.
