For any ungulate, whether skin is on or off, insert a knife blade deep next to the dorsal protrusion in front (neck side) of the withers. Pretty much just the same way you’d begin to remove a backstrap except you aren’t removing anything. Give it the smell test. It will tell the story. This location is at the core of the animal and is one of the most difficult places to get cooled properly. I have detected the odor of sour in as little as a day on a large bull – a well dressed bull and not in particularly warm conditions. For smaller animals the time can be even less.
Do whatever you are going to do but this test has convinced me that anything I can do to cool an animal’s core outweigh any benefit of leaving the skin on.
