From what I've researched about invisible fences, they aren't effective when you're dealing with a mastiff, because of their high pain threshold. I was considering an invisible fence for the front of my property, (the back is fenced in), but I found people who reported that their Cane Corsos (which is what I have) had "broke the barrier" in spite of being repeatedly shocked; they got shocked going out, and got shocked trying to come back in... I'd imagine this would discourages your animal from coming home if he does get out. Definitely not what I want.
Also, from what I understand those are made to keep your dog in their yard, but it doesn't keep OTHER dogs out of your yard. There's just too many people who thinks it's fine to let their dogs roam free, I disagree, and I certainly do NOT need them on my property when my dog is out. Needless to say, I decided against it.
