My Rhodesian ridge-back pup is scared of rabbits, can you help?

Well he's not that small anymore. He's about 4 months old. I bought him from a South African friend of my dad. His father was a great hunter, so was his mother. He came from good stock. These dogs were used in Old Rhodesia (present day Zimbabwe) to catch lions, leopards etc. My pup is a freeking whimp. It wiII kiII the animal, but spends like half an hour circling it and backing. That is so annoying! I need a dog that will attack on command and rip apart everything. I'm going to use it for Wild Hog hunting, and it can barely kill a rabbit!