A few things to consider
1.) Animals behave very differently in captive settings than in the wild. When you have animals in close quarters, you are essentially forcing interactions, some of which may not occur in the wild. Wild dogs do not (generally) prey on giraffe in the wild. In an enclosed space, with the animals constantly running into one another, an attack is much more likely.
2.) It doesn't matter if the wild dogs go after the giraffe or not. All that matters is that giraffe might think that they could. In this case, the giraffe will either a) lash out and kick the dogs to death, or b) run around in a panic and break legs, necks, or what have you.
There is no version of this that will have a happy ending.