We are living at a great time for screen comedy, because there are no limits. Take, for example, “Strays.” By the standards of just 10 or 15 years ago, the movie is wonderfully, amazingly and jaw-droppingly crude. Here and there, it almost goes too far, but its power to surprise is a huge asset. You won’t believe what you’re seeing.

It’s a live-action movie starring talking dogs that is very much like dogs themselves — soulful and sweet but crude. “Strays” occasionally demonstrates a grandeur of spirit, but it also shows dogs eating each other’s feces.

The brilliant comic observation behind “Strays” is that dogs never quite get the complete picture. They misunderstand much of what they see — they believe rival dogs are in the mirror and that the mailman is the devil — and thus by staying entirely inside the dogs’ point of view, the movie taps a major source of humor.

如果狗能拍电影,他们会拍电影exactly like “Strays.” They’d make comedies thattheythink are dramas.

Will Ferrellis the voice of Reggie, a scruffy border terrier who thinks that his human, Doug (played by Bay Area nativeWill Forte), is the greatest person in the world, when we can actually see that the guy is a mean wastrel and a pothead. Doug can’t stand Reggie, but Reggie doesn’t know it. The dog thinks that it’s just an interesting game that Doug keeps driving him far from the house and dropping him off.

One day, Reggie is driven so far from his home that he can’t find his way back. He’s in a rundown part of the city, where he meets Bug (voiced byJamie Foxx), a street-smart Boston terrier, who introduces him to two of his friends — an Australian shepherd named Maggie (the voice of Isla Fisher) and a Great Dane named Hunter (the voice ofRandall Park).

These new friends break the news to Reggie: He is now a stray. That means Doug doesn’t love him.

Most of the movie depicts the four dogs on a long odyssey, and Dan Perrault’s screenplay comes up with a series of novel incidents that are lively and amusing. Here and there, the gross-out humor becomes a bit much, but everyone has a different tolerance for these things.

“Strays” uses computer animation to make it look like the dogs can talk, and if you didn’t know any better, you’d believe it was all real. The verisimilitude is astonishing. The dogs move their mouths and lips to enunciate the various consonants and vowels, and because different dogs have different kinds of mouths, each mouth moves in a different way.

通常,在这些类型的电影s, the voice performances are merely functional, but the voice acting in “Strays” is noticeably good. The fact this runs uniformly throughout the cast probably says something about director Josh Greenbaum (“Barb and Star Go to Vista Del Mar”). He presides over a film in which the acting is big enough to register, while never degenerating into mugging.

But two of the performers must be noted in particular. Ferrell brings out all the sweetness and pain of a rejected animal and then, later, all that animal’s fierce, uncomplicated rage — while managing to still be funny the whole time. Meanwhile, Foxx is able to create a character that’s proud and self-reliant, while covering over his own life disappointments.

Yes, it’s odd to be talking about dogs in this way, but comedy is grounded in the truth of its characters. With Ferrell and Foxx, “Strays” finds a firm grounding.

What’s more, “Strays” has a wild finish — one so strong that I laugh every time I think of it.

Reach Mick LaSalle: mlasalle@sfchronicle.com