An uninspired all-the-best-parts-are-in-the-trailer remake, this is a showcase for two things: Tim Allen’s mugging and some computer wizard-style special effects. The limited entertainment value of both items and a solid supporting cast are not quite enough to make up for a predictable script and faux aw-moment theme.

Allen plays Dave, an assistant District Attorney in the middle of a big trial that is his chance to show he can handle the top job. A high school teacher is charged with starting a fire in a lab that tests animals for medical research, and Dave wants the jury to find him guilty.

He is so preoccupied with the trial that he doesn’t notice the problems at home. His son is failing math. His daughter is one of the protesters at the lab and she thinks her teacher is a hero and her father is the bad guy. And his wife (“Sex in the City’s” Kristen Davis) feels neglected and abandoned.

It turns out something fishy, or, I should say doggy is going on at the lab. Dr. Kozak (Robert Downey, Jr.) has captured a mysterious sheepdog that is still healthy and youthful although it is 300 years old and is trying to find a way to transfer his genetic makeup to humans. When Dave is bitten by the dog, he starts scratching behind his ear, lapping up his food, and growling at his opposing counsel. Then he turns into a dog.

This sets the stage for two developments: mildly amusing mix-ups as Dave-the-dog tries to navigate the human world, transforming back and forth from mannish-dog to doggish-man and lessons learned as Dave discovers how many things he wants to be able to say, now that he can’t do anything but bark. The lab experiments include CGI genetic cross-breeds like a dog-frog combo that exemplify this movie’s own uneasy mixture of slapstick and sentiment.

It feels too long, even at 98 minutes, over-stuffed with an under-used supporting cast that includes Davis, Downey, Danny Glover, Jane Curtin, and Philp Baker Hall. Craig Kilborn, in a brief role, manages to wear out his welcome quickly and then hang around to wear it out again.

Whether it’s a fantasy-comedy or a fantasy-drama, whether a magical spell or some plot-driven subterfuge, transformation in a movie plays the same role as any other epic journey. It gives the character a chance to understand who and what he was and to learn what he can do better.

All of that happens here, as Dave learns that he wasn’t really paying attention to his family and how much he needed them. But the set-up is so indestructible and the dog is so irresistible that, buoyed by Allen’s willingness to do whatever it takes for a laugh provide some light-weight pleasure.

Parents should know that this movie has some crude language and humor for a PG, including bathroom jokes and and references to body cavity searches, getting “fixed,” and being “sold” in prison. At one point, the kids are concerned that their parents are splitting up. A strength of the movie is the positive portrayal of a friendship between people of different genders and races.

Families who see this movie should talk about what being a dog helped Dave to see differently. Why did he neglect his family? Would you like to live for 300 years? What would you do differently? Families who want to find out more about the issue of animal testing can find it here and here.

Families who enjoy this movie should see the original, with Fred MacMurray and the sequel with Dean Jones, The Shaggy D.A..