All npcs currently just basically follow you until you either find a area they cant get up/down or you or they die. As outrunning them is too "hard".
AI needs a much deeper mechanic to determine when it should stop chasing a player, i suggested a sort of threat mechanic where repeated aggression towards the animal will make sure it chases you longer, while just the right aggression and/or running away will end up in the animal/npc giving up the chase. If its just a set leashing distance it becomes highly exploitable, it needs more variables.
Also;
Most ai needs to have their attacks changed so they actually fit into how the rest of the combat works.
Wolves, razorbacks, hunter lizards and bears attacking every 0.3 seconds is NOT ok when the rest of combat is slower. Leaves little room for defense(other than passive), bears and razorbacks having unblockable attacks sure as hell doesnt help either. Animals should all fight differently in a way that applies correctly to how everyone else fights. Right now it feels like two different games combat fight each other. Its like I bring a deck of pokemon cards to a magic the gathering game.
Suggestion? since animals don't utilize blocking and have significantly higher speed than humanoids(regardless of which animal it is atm anyway).
Wolves: Wolves should use their speed(much like now how they now attack you a little bit, then back off and then come at you again), imagine a wolf attacking you, it would not just attack you from one direction continuously, then run back sit for a bit and then run in back at you. It would go in, bite maybe do a double attack combo at the speeds it does now which might give you time to block or attack or a try at mix of both, then back off, not stand still but rather pick a set distance from you, then trying to circle you. With one wolf this may not seem like much, but it will make the fight not only more easy to grasp for players, it will seem more realistic and will really shine more when there are multiple wolves. They'll run in, do just a couple, more manageable attacks(than the never ending super fast spam of attacks that deal less damage they do now) at more damage than they do currently, then back off. Which would mean it would be pretty hard to focus on a single wolf and make them much more "dangerous" when there is a couple of them, as you'll be chewing down their collective HP rather than one at a time like how it mostly plays out right now due to higher prevalence of them getting out of range and more movement around you making it harder to keep track of any one wolf to focus it down(when alone anyway).
Bears: Henrik has already mentioned things like bears pinning you down and being in your face is how they will fight in the future. Make them have a mix of very low damage swipes and hard hitting slow attacks that can be dodged or parried with clear telegraphing. If pinned then to break would be a mix of causing damage, blocking and pushing the bear. Anything other than what we have now please.
Boars: They already sort of have something going towards making boars a bit interesting but clearly its nowhere near where they should be. Boars currently attack and then try to charge at you with a pretty slow and easily dodgeable attack after turning tail on the player and running a couple meters.
Suggestion? Play out on this more. Right now the razorback trying to gain distance by running away from you, usually just ends up with the player chasing after hitting it and then getting hit by the charge at point blank which achieve nothing cool or fun gameplay wise. Give the boar a very slow, blockable but well telegraphed attack that knocks back the player hit a significant distance(which makes fighting razorbacks at height or in weird terrain potentially more dangerous, plan the locale if you can). After being hit the player is then knocked away a significant distance, the razorback then decides to charge at the player. This should be a charge that is significantly faster than currently but just like how it is now pretty easy to dodge as the razorback does not steer when in this charge. Anyone caught in the charge gets hit. Horse you are riding, people in your party that happen to get in the way etc. IF it hits you, it has a REVERSE impulse, meaning it pulls you in towards the razorback a little bit(doesn't really have much of any effect other than sort of cutting off player sprinting, and giving being hit by the charge giving you some feedback and setting you up for further hits by the razorback). The razorback then attacks normally with attacks that hit a bit harder than currently, but slower. And most importantly, blockable.
The charge would remain an unblockable attack. It would also be an opening move as well as a possible move it does when the razorback switches target to someone who is further away. A charge telegraph such as the boar making a squeal and making those stereotypical hoof scratching animations that usually follow with a charge would make sense, too.
I think the most important take away is, animal attacks should be overall blockable and the ones that are slow and unblockable(or basically go through your block regardless of parry timing) should be dodgeable mechanics. Meaning fighting animals is a mix of pushing, attacking, dodging, reading attacks and blocking. Which is very specific to each animal due to their way of fighting.