Zombie dog damage doesn't correlate

It seems to be that Zombie Dog's damage is set when you first summon them, and any changes to your equipment afterward doesn't effect their damage output until you resummon them.

Is this working as intended?

Their attack speed also doesn't seem to correlate to your witch doctor's either, so it's best to put on your highest damaging weapons and attack boosting items to have the highest dps possible when summoning them, and switching(or not) back to whatever you use for your build type.