Fear causing Howls

[Conan The Conqueror]

A number of animals/monsters have a howl that can cause fear, but even though I get an intiative check from the howl, I never have to make any kind of save and I've never been feared by the howl.

[Drakill Tannan]

My shadow mastiff (From shadow conjuration) has never scared a single enemy, even though it has used the howl several times. But maybe i'm just unlucky.

[Professor Death]

My mastiffs seem to work sometimes and not others, but usually the effect seems to stun opponents, not cause fear.