Starring Bruce Greenwood, Josh Hutcherson, and Steven Culp. Rated G.

When the actors who played John F. Kennedy and his brother Robert in the Cuban Missile Crisis drama Thirteen Days turn up as second bananas to an incorrigible, long-legged Irish terrier in the family dramedy Firehouse Dog, one might reasonably suspect that the end of the world is nigh. But in this pet-friendly tearjerker, Bruce Greenwood and Steven Culp prove that they're pros whatever the script. And, really, could it be much different than playing opposite Kevin Costner?

Firehouse Dog is a fish-out-of-water tale featuring Rexxx, a famous canine star of such flicks as Jurassic Bark and The Fast and the Furriest who plummets from a plane into a tomato truck when an aerial stunt goes awry. Deprived of his celebrity status, the vain Rexxx begins life anew as unofficial pet therapy for Shane, the bratty 12-year-old son (Josh Hutcherson) of an emotionally tangled single father and fire captain, Connor Fahey (Greenwood).

The plot line might sound like a lark, but in reality the far-fetched Firehouse Dog touches on very heavy subjects like loss, guilt, responsibility, corporate greed, and arson. Thanks to some devastatingly realistic canine whimpering and Greenwood's ability to convey soundless despair, Firehouse Dog is blubberingly poignant, although never overly tragic.

Comic relief comes in the form of a bumbling, bickering firefighting crew. More compelling, though, are Culp as one of the firefighting brass and Rexxx's romantic flashbacks, wherein our hero recalls a finicky Dalmatian with Bo Derek cornrows dumping him for a suave, silver-haired Afghan hound in movie-star shades.

A family film, Firehouse Dog eschews sex, drinking, and profanity, and the only smoke emanates from torched buildings. The ridiculous number of fiery explosions here set up the obligatory pet-in-peril scenes. Sensitive viewers, like the burly security guard who told me after the screening that he'd cried twice, might be traumatized by the prospect of Rexxx becoming a hot dog. His reaction, and the fact that the film is dedicated to a pooch named Rosebud, merely prove that people's love for their four-legged buddies knows no bounds. That's precisely what makes Firehouse Dog so darn touching.