Death and Decay plus Unholy Blight accounted for 85% of my output on a boss fight. WTF was I doing?
10 man version is on the left and 25 on the right. The red circles are Gluth where he should be tanked on the far side of the room. The light blue squares are the grates where the Chow's spawn. The black circle is the path you should run in and the arrows point the way. The red X is where you should drop your Death and Decay.
In normal mode the Chow's only spawn from the center grate so it makes sense to keep your DnD right next to it. In the heroic version they spawn from all 3 grates. This requires you to run in a larger circle and placing your DnD near the middle of the room will go a long way to ensuring that you pick them all up as the run for the dog.
In both cases getting an earth bind totem or frost trap makes things a bit easier. Having unholy aura does as well. The reason you run in a circle rather than back and forth is so you can avoid as many of the infected wound stacking as possible. You want to keep these low so you don't get instagibbed by all the chows.
Since you are running in a circle and have all of the Chow's aggrod on you, they will be nicely packed for AOE during the decimates.
Last, if one seems to be getting away you have IT, Death Grip, and Death Coils to bring them back to you.
Keep your Bone Shield up and you'll do your part to down a boss and toss some really impressive DPS to boot. Just kidding on the DPS part.