My answer is a bit outdated, as it does not address changes since higher MP levels were added. I am adding information for higher level play to update it.
For lower level play (< 60):
Sacrifice becomes much more effective when combine with additional abilities designed to give you more zombie dogs.
The Next of Kin rune for Sacrifice is a big help for sacrifice builds, giving you an excellent (35% per dog) of getting new dogs after a sacrifice.
The Devolution rune on Confusion effectively gives you a second zombie dog cool down timer, as any enemy killed while confused has a 50% chance of spawning a new zombie dog (up to your maximum number of 3, or 4 if you have the Zombie Handler passive).
Sacrifice does a lot of damage, particularly with the Pierce the Shroud passive and Soul Harvest. With 3 (or better yet, 4 with Zombie Handler) dogs exploding at once, you will clear out most normal groups, and do enough damage to champion packs that they should be easy enough to clean up.
With good Next of Kin procs, and possibly a mid-combat resummon, I found it to be a very effective tactic in early Nightmare.
Charge the group, Soul Harvest, Sacrifice, repeat Sacrifice until either the group is cleared or you are out of dogs, then resummon (and repeat if it's a champion pack or unique that is still up). Cast Confusion on a group of normalsif you need more dogs and Zombie Dogs is still on cool down.
However, it is difficult to concentrate your dogs on one target, is a bit too reliant on luck and long cool downs, and is useless against a number of bosses.
For higher levels of play (level 60, MP1+... MP level depending upon gear):
Sacrifice can become an effective way of replenishing your mana at higher MP levels, although its effectiveness will likely fall short of full MP10 play unless you are exceptionally well geared.
Once you are farming higher MP levels, Gruesome Feast and Grave Injustice become incredibly effective for maintaining a constant farming pace. Grave Injustice has an additional synergistic effect with all high-cooldown skills, including Summon Zombie Dogs.
This makes Sacrifice->Pride an effective backup for when you run out of mana, particularly on elite packs and bosses. The reduction in cooldown from GI means that it is fairly easy to keep dogs up at all times for anything other than a boss battle.
During elite fights where I am not able to quickly burn the pack down, I rely on Big Bad Voodoo -> Rain Dance, or Sacrifice -> Pride, to recharge my mana mid-fight.
Adding the Final Gift rune to your Zombie Dogs provides some small synergy with Gruesome Feast, extending the benefit of surviving those longer fights.
During non-elite battles, you should be blasting through packs of minions so fast that your timers for BBV and ZD will reset in between almost every elite pack (the exception being a few areas exceptionally dense in elite packs, such as Vault of the Assassin). To maximize the effectiveness of this, high damage skills that should one-shot packs (or at least come close to it) such as Zombie Charger -> Zombie Bears and Soul Harvest -> Vengeful Spirit are recommended.