I first saw this movie as a kid and I actually had a theory Don Johnson was delusional and hallucinating the dog telepathically talking to him!

I mean think about it, what evidence do we see the dog was altered in a high tech lab to be super intelligent and psychic? Even if it was, in the movie its clearly been a decade+ since the nuclear war so how is the dog still alive?

It makes more sense to me the dog is a dog, and Don Johnson has gone insane due to trauma and isolation heh.(yes I know its based on a short story)

A bit of warning for modern audiences, this is a black comedy and our main character is openly a rapist! And his motivation for most of the movie is having the dog sniff out women to rape in the wasteland.

Also has a "twist" ending I found darkly hilarious, your mileage may vary.