Dogfood is actually a cat.
Let's look at the surface evidence first. Despite that dogfud has a dog as his avatar, we know that his name is actually "dog
food". Now, we really have no evidence that dogs actually eat cats. However, we do know that dogs really like to chase cats around, just like how cats chase mice, except cats actually eat mice when they catch them. Therefore, we can assume that when cats are being chased by dogs, they believe that they are "dog food".
Next, we know from observation that cats
really love to kill things. This suggests that cats are very violent and sadistic creatures. When Dogfood took the
Dante's Inferno test, he ended up in the 7th circle, which is reserved for the especially violent of creatures. Coincidence? I think not.
To continue, we notice that Dogfood
loves posting pictures of alligators / crocodiles in the cuteness thread. Now a crocodile / alligator does resemble a giant fish somewhat. And which animal loves fish more than cats? No doubt Dogfood dreams of having giant fish for him to feast his greedy feline paws upon.
Finally, Dogfood is a dancer. And clearly only cats are graceful enough to be able to perform anything close to dancing. Dogs just don't compare in this field. So in conclusion, my grand unifying theory states that Dogfood is definitely a cat.