aww poor pup

Yeah, they need a bit more time to know each other :)

Was he the former boy who eats a dog food?

No, He's not the same guy
But the same fate

Have he been eaten a dog food too, or it's another trigger: the magic dog harness?

As I see, now he starts to restore his human mind, but lost the ability to communicate with dogs because they see he acts strange. This is one fo a few interesting topics: post-TF events. Usually, TF-author does not bother to write or draw about it. But I always wondered, what an animal with human past can do, how he can live? Because, as you said, his chances of changing back are slim.

I'll draw event as he transformed later but it is not because he ate dog food.
I try not to draw the same cause I had drawn before.

And yes I think "post-TF events" are quite interesting too. It was fun to think what would happen to their lives after it happened. What do they have to face after this? How will they adjust after this? and if they can't return to their original human form, How will their lives end?

I may continue to draw his story and other people's stories as well.