Dog ultra-sonic dog repellent guns??

[blackie's maiden]

Been reading reviews on Amazon. Wondering if this could be good protection for.goats.and.hikers.from preditors, like.domestic dogs, big cats, maybe even bears (?) without scaring goats.to.death or freaking out the dog owner since hopefully they can't hear the ultrasonic sound. Any experience with these things. Says it can be used on cats.too so wondered.if.all potential preditors.have.hearing as.sensitive.as.dogs.and cats.and maybe not.the goats? Thanks.