Hi Lesley
Depending on the dog, it is possible that it has put the hogs off going through that garden. Is your garden linked with any others – if not, that might be something to try.
Having said that, there are all sorts of other reasons why hogs might disappear. i.e. someone else is feeding them somewhere more accessible, their route has been blocked further back, the females are busy with hoglets, etc. Other than encouraging as many people as possible to make hog holes, the only thing you can do is hope that they find a way through somehow.
Good luck.