I am legend.

And, if you're feeling brave, the original Star Wars trilogy

Space balls although technically it's a mog!

The Wizard of Oz, maybe? Toto is important, and moves the plot, but then, maybe he's just a MacGuffin.

Cujo

Anchorman: The legend of Ron Burgundy

The Mask

Supergirl

"Good Boy". Its a pretty basic haunted house movie, from the perspective of a dog.

Finch

Post apocalyptic world with Tom Hanks, his dog and a robot.

Air Bud is a dog movie on the surface, but has a surpisingly well done underlying story of a boy struggling with the loss of his father.

A Boy and His Dog?

Dogville.

Or maybe I misunderstood the question, and/or the movie.

The dog is a drawing on the ground. It has a very small part, yet the dog won an award in Cannes for the movie.

Is ‘guy dies and is reincarnated into a purgatory-like existence of a sapient dog that lives with but cannot communicate with his family’ a dog movie that’s not a dog movie? Because if so, Fluke. (It is very poorly reviewed)

Funny Farm, I Am Legend, The Outlaw Josey Wales

Iron Will

Prey.

Would Wolf Children count? It’s about a single mum raising werewolf pups. Anime film.

Toy Story

Dog Soldiers

The Shaggy Dog?

Quigley (2003)

Isle of Dogs. Not a dog movie but a coming of age with a lot of dogs.

• I Am Legend
• A Boy and His Dog
• The Plague Dogs
• Mad Max: The Road Warrior
• Cujo

I know it's kinda unrelated,but man my wife had me watch A Dog's Purpose... Dude I cried kike 6 times. Shit is vicious.

Alien³

So, like some sort of dog, not dog draft?

Scooby Doo