Is there any way to make DF creatures bleed out in a longer, more protracted fashion? Increasing the vascularity of tissues seems to make them shoot a bit burst of blood at first, but it still doesn't keep bleeding for very long.
Bleeding is weird. The vanilla vascular ratings are way too low for anything other than a death by a thousand cuts and bleeding is naturally staunched at the same rate, with no regard to creature volume, wound size or tissue healing rate.
When a vascular tissue is cut, it splashes out the first "tick" of bleeding right away and then bleeds out at a rate of X blood per tick, where X is adjusted by vascular rating, wound contact area, artery hits and whether a stuck weapon was twisted free from the wound. It naturally staunches at a rate of 5 blood units/tick on average, but I've seen it do jumps of 2-10 units between turns. The total amount of blood in a creature doesn't seem to be related to vascular ratings at all, I'm guessing it's just body volume.
Cut arteries increase blood loss, obviously, but I haven't figured how much damage it does and whether it's a multiplier or not. Cutting a major artery is a killswitch that kills a creature of just about any size in less than ten ticks. My healthy dwarves usually go down after moving 7-8 tiles. The destroyed heart of a giant gouts blood at a rate of over 10 thousand units per tick.
To answer your question, try giving your tissues two-digit VASCULAR ratings for a start and see what happens. Even a dwarf with VASCULAR:250 muscle could survive a deep gushing gash across his chest until the bleeding stopped. VASCULAR:750 and an artery hit is enough for instant death.
