Well, OK, it rarely is good together. Animals in general, and dogs in particular, tend to get short shrift in fiction. Especially movies. They're usually used as cheap plot/character development (where human character develops by the dog's death), and/or nothing but symbols for something that doesn't involve them being real animals. I wish they would make more Dean Koontz books into movies. He reliably has the dog not only play an important role in the plot, but live at the end.
On a side note, when we went to see I Am Legend in the theater, I started crying at least ten minutes before the dog actually died. I could see it coming a mile away. And nothing chokes me up faster than a Brave Dog story, true or not.