It had been arranged for a real lion to be used in filming, and to be dyed black. However the insurance costs required for filming actors with a real lion were astronomical, so a digital lion was a much cheaper option.
Four dogs play the character of Wrolf. They all had their fur dyed so they looked identical, and each dog had it own talents. One was particularly good at barking, another at licking, one at running and one was good at just lying around.