It's not about being OP. It's about realism. What kind of animals would build thorns in real life? Also real thorns have roots so you couldn't move them.
This sounds hard to do, but hey Sims has similiar things (or used to have) and Minecraft is a whole game about building terrain, so why couldn't this be in niche too!
Maybe change the wolf-sheep claw stats to +2 strenght, +1 fishing and +1 speed, since wolves don't really fish that much (neither do sheep) and can run long distances