UB, Use long chain (minimum 6') and heavy drag (2 lbs - 4 lbs) for canines. I use the same for Coon.
With long chain, many times a critter has chain wrapped around something and drag is laying on ground.
Lite weight, 2 prong, rod grapples don't work as good as heavier grapples (drags). They bounce, causing them to not hang up at times.
I haven't had problems since I switched to a heavier drag.
No spring devise is needed for drags.
Common sense is to use drags closer to cover. Just look for critter at the closest cover.
But trap'n things are written in stone...One season the ground was frozen hard and deep with 6"=8" of snow on the ground. I set traps with drags 300 yards from the nearest cover. Lots of Reds moved back to this location and I had to set it...LOL. None of the Reds I caught made it to the cover. All were hung up on corn stubbles. Cut corn stalks in the wide open.
Finding or following critter on a drag can test you at times. If critter is caught and hits the cover then it snows...well a routine trap check can turn into an Africa safari!! At this time it's good to carry the .22LR rifle and leave the pistol in the truck.
I leave drag lay on the ground behind set and cover with weeds, leaves or ground litter. I do dig a narrow channel to lay the chain below the ground for a foot or two from the set.
Place a Golden Rod, small branch, corn stalk (something natural) at your drag. That way you can check from long distance with binos. If your flag is down...go check closer.