As the poster said correctly above, "rather at the hind end of a departing animal" - I would add an already wounded animal.
On Water Buffalo, even a good solid hit to the vitals will not always drop it on the spot so if the animal is hit and turns and runs, I automatically go for either hip, deending on which side I am on.
I have found on numerous occasions the HIP shot to be very effective for stopping an animal from continuing to run away, allowing a coup de grace shot.
If using an FMJ, it genrally keep going through to the vitals anyway - and sometimes on and out !