Coprophilia

My wife caught the family dog in her pen today eating a freshly dumped load of recycled Science Diet. I figured this was like when animals eat grass or rocks, or like when rabbits eat their own pellets (rabbits drop two kinds of leavings - one they can re-eat, the other they can't, for reference, see Rabbits: The Mystery of Poop), and that there must be a medical reason. Unfortunately, this is entirely wrong. Our dog is just gross.

I quote from the article Pooteewheet found:

Some dogs can't resist a tasty morsel of feces. These dogs will eat their own excrement or that of another dog. Some prefer horse feces, others cat feces. Frozen feces are popular in the winter time...

Dogs are historically scavengers, and this is believed to be a scavenger behavior...

Owners find this habit in their pet disgusting -- particularly when the consumed feces are thrown up all over the new carpet.

At least with your dog you can be relatively assured it's not a sexual fetish. But if you linked here as a newbie to the scat scene, might I recommend a brief journey over to the Coprophilia entry at Wikipedia where you'll find such useful information as:

Other slang terms describing this practice include Meatloafing, FedEx'ng from Browntown and Karling. There are different levels of the Karling. They include:

• Cold Karling - involving a process similar to the Cleveland Steamer.
  
• Warm Karling - involving a process similar to the Glass-Bottom Boat.
  
• Hot Karling - The same thing as a Warm Karl except without the plastic wrap.