If they died from starvation then the log would have reflected this = it CAN happen even if they had plenty of food if the single player or server settings are “wrong” … ie not default which can happen randomly even if you haven’t changed them from what I’ve seen of other people reports…
So a couple of things might kill them to be considered:
If on follow then as it teleports to be close to you it might teleport onto spikes or palisades and instantly die => had that happen to a thrall of mine a long time ago.
Again if on follow and your base is more than one level it might teleport to you and fall to its death if it teleports to where there are stairs or ceiling pieces … as the game randomly will place the teleporting thrall/pet before it’s rendered the building…
ditto if the pet was on follow and you used an elevator => the game can randomly decide to teleport the pet to mid-air next to you instead of solid ground/building piece.
Outside it’s harder to diagnose if the event log doesn’t say pet killed by X…but my main suspicion would be they moved to where they got damaged by spikes or palisades … possibly in response to going to fight an npc that spawns nearby and pathing back poorly ending up close to the spikes
OR if you had been on a server then moved in response to a player running by and ended up near the spikes.