That's very sad. How old is he? Cancer usually happens in elderly pets. All of my 15 dogs died of it.
I'm sorry to hear about this. Although I think he can survive it, because you even said that he's pretty sick. *ba dum tss* Seriously though, I hope he'll feel better soon.
Uh, hey, Aeon, there's an edit button for comments, you don't need to delete your comment and make a new one.