My wife's arti is around the same. She also dismisses and re-summons him when it happens, but sometimes it will happen multiple times within the same quest. Several times, she's gotten irritated enough just to not bother re-summoning him. We are usually duoing quests, but I haven't seen any particular pattern that causes it. We also usually run elite quests, so even when he's not bugged, he usually dies multiple times anyway. Basically, it doesn't really contribute much other than frustration.
Wait a minute here. The dog doesn't follow directions, aggros too much and dies, stands in traps and dies, can't heal itself, whines about needing heals, and raises the general frustration level of the rest of the party. Now that I think about it, Turbine's AI behaves almost exactly like far too many players in the game.