For what it's worth, one problem is that DF simply does not care very much about body heat except in terms of it totally destroying bodily tissue.
In the real world, you're completely screwed if your brain and other organs reach a high enough temperature, even if it's not high enough for the tissue to catch fire/melt (your body's internal systems don't cope well with being heated to 120 degrees all of a sudden).
In DF, however, I've literally seen people sustain
burn wounds to the brain in Arena Mode. Brain matter in DF has a heat damage point of
282 degrees Fahrenheit. Think about that.
Realistically speaking, even if DF doesn't represent the massive shock/trauma associated with such a quick rise in body temperature, it should at least simulate the effects of a fever at that temperature, causing creatures to become ill at high internal temperatures and die if it gets too extreme.
Of course, fatty tissue has the opposite problem, melting and sloughing off your body at the drop of a hat. See
this bug report I wrote up a while back. By DF's logic, if you have a high enough fever (or heat stroke), all your fat should just liquefy and leak out your body, since in DF it melts at 110 degrees Fahrenheit, just barely above what constitutes a very dangerous fever. I have no idea why Toady hasn't fixed this, since it has helped to contribute to bugs in the past, such as the infamous "rain bug".