How to Deal with a Death Knight's Ghoul

Coping with the undead
Whenever you fight against a Death Knight there is more than just the plate wearing, glowy eyed psycho in front of you to worry about; there is also his pet ghoul to deal with. The threat this little beast poses to you differs greatly depending on talent expenditure but is always something you need to keep an eye on.
When it comes to Ghouls there are two main types you need to concern yourself with; pets and minions. By default every Death Knight is capable of summoning a Ghoul minion for 2 minutes which is not under the players control, this minion is generally weak with low damage output and health while being highly susceptible to AoE effects.
The main problem with a minion Ghoul is that it is an excellent target for the Death Knights ability Death Pact; this sacrifices the ghoul in order to restore 40% of the players health. This sacrificial heal is capable of critting for a 60% heal and can be further boosted by Vampiric blood; when fighting against Death Knights it is in your best interests to prevent this.
So how do you prevent the Death Knight from sacrificing his Ghoul? The theory behind it is simple; most players who plan on sacrificing their minion only summon it when they need it and while the Ghoul is clawing its way out of the ground it is unable to be targeted by Death Pact preventing an instant sacrifice. As soon as you spot the Ghoul being summoned you should use whatever incapacitate or silence effects you have on the Death Knight before quickly killing the Ghoul.
Should the Death Knight be foolish enough to summon the Ghoul before he requires it then make sure to kill it first; not only will he not have the runic power to instantly sacrifice it but there will be little to no damage on him to be healed.
When it comes to dealing with pet Ghouls things become a little more difficult; unholy Death Knights are able to precisely control their Ghouls, giving them specific targets to attack and being able to recall the ghoul safely from danger. When the Ghoul is controllable it also gains the ability to stun its target for 3 seconds every 30 seconds in a similar manner to a Hunters Intimidate skill.
Pet Ghouls typically have large amounts of health too and are able to Huddle to reduce all damage taken by 50% so simply CC’ing the Death Knight while killing the Ghoul is rarely a good idea as it will require significant effort; further to this an unholy Death Knight is able to resummon his Ghoul far sooner than any other spec due to the Night of the Dead talent.
Due to this speedy resummon and the pet Ghouls higher health pool a further threat becomes apparent; a Death Knight is able to command his ghoul to explode by casting the spell Corpse Explosion on it where it will detonate after a short time for 25% of its health. This explosion can typically hit for nearly 5k health, causing obscene burst damage in combination with normal attacks.
So how do you deal with this versatile monster? The best way is to control it; unlike most undead it is susceptible to fear effects as well as anti-undead spells such as Shackle Undead and Turn Evil; use such skills to buy yourself time to engage the Death Knight on his own. Alternatively if you have a friend nearby with a taunt skill it is possible to taunt pets off their current target and onto a more sturdy class making it a great means of generating free rage or Rune Strike procs.