I have a dog catching trick that I used with huge success a number of years ago to catch a dog someone had dumped. It was terrified of me and everyone else.
I contacted then Fish and Wildlife, now the Conservation Service (I think or something like that) the people who catch bears in that big tubular metal trap. They came with the big bear trap, put some meat in it and we had our dog the following morning. Many days and frustrating sightings preceded this, but it really worked well. Happy ending!
Maybe they would help out as it is not bear season yet and the traps are idle. You could always offer to pay them.......
Hope that helps and good luck,
Louise Walters