I have had a bit of time to look for the snake I found in our garden and found that it was not a Cape Cobra. I will try to attach links to the sites I found it on.
Turns out it is a juvenile yellow house snake called Lamprophis Aurora. Well, at least it is not deadly and I do not want to discourage the dog from killing snakes because there's always a possibility that it can be a Cape Cobra since we have found one on our porch before. It is just not a chance I am willing to take with two little girls playing outside!