our doberman in the back yard worked well
Good luck I do not have that problem.
Bars of Ivory Soap, hang them along the barrier that you don't want them to cross, about 4 feet high, about 4 feet apart. (drill holes, if you try to punch holes, the bars break. tie with string.)
Coyote urine, tho that may be a bit difficult to acquire. :P There was a product made a few years back, not sure if they make it anymore, called "Liquid Fence" that had coyote urine in it.