I was recently sent a photograph of a severed kudu bull's head. No background story about the kudu was given to me, although the graphic photograph certainly showed how the kudu must have suffered horrifically, although it obviously survived well into adulthood. I'm led to believe the kudu was shot in South Africa, although whether to put it out of its misery, or if it was shot before the severity of the horn deformity was noticed, I have no idea.
The initial horn deformity was probably caused when the kudu was still a young calf. Perhaps due to the horn being damaged and bent downwards. You don't need to delve much deeper as to what the probable cause was because the photo in itself tells the story, about how the animal must have suffered acute discomfort while the horn continued to grow, with the horntip ultimately forcing its way right through the left eye and then up through the brow.