The lil' Griz's will cost you big bucks but are IMO the best "dog proof" coon trap out there. The coon cuffs are nice too but not as nice as the griz.
Having said that 1.5 coils are super cheep and easy to find used at a resonable price.
If you are worried about pets finding there way into your traps investing in some offset or laminated traps would be a good idea with minimal extra cost. You can make these traps "Dog Proof" several ways by being creative. The easyest way would be to use a coffe can or simalure container and cut a hole in the top about 1.5" around. Next dig a hole deep enough that when the trap fires it dosnt hit the top of the can. Bed the trap in the hole STAKE it well as having a pet run loose with a trap on it's paw is much worse than having one waiting there when u get home. Now place the can over the trap in the hole so that the final hight of the top of the can is about 1/2" below the serounding earth. Chuck soem chicken or better yet fish down in the can. The coon will reach down into the hole cut into the can (3" or so to hi tthe pan on the trap) and get cought. If a dog trys to dig it up it will snap. Finnal peice of advice is if you do get an unexpected bycatch use a Y shaped stick or a catch pole when removing the animal, even if you are the owner. Bad thing can happen by acident. Hope that gives you some ideas and I didn't make it sound harder than it is. By your 3rd set I bet this will take you all of 5 mins to make.