The ones that only vibrate, like a mobile phone on silent, when you press the remote control. Would these be any good for a dog that gets really focused on other dogs when it sees them in the distance and ends up freezing and then often barking when they get close (when he's on lead.) He does this a lot and half the time he actually wants to say hello to them and play. Treats or a toy squeaked near him can sometimes break the spell and once distracted he doesn't react.
He is neutered, well socialised, doesn't bark at all at off lead dogs on the field he is sometimes walked on when they get close (whether he's off lead or on lead) but still does the freeze and stare.
I was hoping a vibrating collar would work but, if not, any suggestions as to what positive reinforcement might?