If you're old enough to remember the "Lassie" movies and TV show from many moons ago, you'll likely recall the moments where the collie would race up, frantically barking. The human there would always say something like "What is it girl?" with the now universal "Timmy's in the well?" coming to mind for most viewers. Of course, "she" could have been saying, "Stop calling me 'girl,' I'm a boy" or "They're going to replace me with a look-alike and you're too dim to notice."
Then again, Lassie may have been saying "The Shaggy Dog is really a boy in sheep's, uh, dog's clothing." And for those who recall Lassie, you'll likely remember that 1959 Disney film and/or its 1976 sequel "The Shaggy D.A." If not, you can get a temporally and technologically updated mixing of the two in Disney's own remake, "The Shaggy Dog."
The first film featured a boy who, after unwittingly activating an ancient shape-shifting spell, turned into a sheepdog (with Fred MacMurray doing more of his "My Three Sons" bit playing, natch, the father). The second had Dean Jones playing the grown-up version of that boy who's running for D.A. but is still afflicted with the canine curse. Here, elements from those films are combined with bits from "Spider-Man" and especially "Liar Liar," with Tim Allen playing what's essentially a kid-friendly, comedy version of the old werewolf tale.
The actor is game for the part, doing his best to mimic all sorts of dog-like behavior, whether of the simple variety (scratching, sniffing, growling, etc.) or special effects ones (running on all fours, morphing from human to dog and vice-versa), although the film thankfully doesn't go crazy or get preoccupied with the latter. The writing quintet of The Wibberleys (yes, you read that right), Geoff Rodkey and Jack Amiel & Michael Begler throw out a lot of those gags as is to be expected, especially with that many writers. Yet all of that's hit or miss in execution, with some being amusing (probably more so to kids than adults) while others quickly begin to feel redundant, not to mention simple and even too easy (or lazy, if you prefer, on the part of the filmmakers).
The "Liar Liar" similarities (a lawyer who shortchanges his family in favor of his career but gets a second chance when a curse helps him see the light, all as he tries to continue performing in the courtroom) certainly don't help matters either. Beyond the thoughts of this one borrowing and/or ripping off that material, the script simply isn't as funny as that of its predecessor. But despite his efforts, Allen isn't as gifted, inspired or imaginative a physical comedian as Jim Carrey proved in that film (and others).
Kristin Davis, Zena Gray and Spencer Breslin play the stock family characters related to the absentee dad part of the plot, but the latter aren't fleshed out enough to make them interesting (although I suppose some younger viewers might identify with the "plight" their cinematic counterparts face). Robert Downey Jr., Jarrad Paul and Bess Wohl populate the other half that deals with corporate genetic manipulation. While cartoonish in construction, these characters are perhaps a bit too heavy for those same viewers (with talk of killing Allen's character to dissect him in order to see what allows him to do those canine transformations, etc.), and Downey appears nothing short of uncomfortable in the role.
But that part of the story does provide for the most entertaining, if odd part of the film in the form of the various genetically altered lab animals. I know, that's not funny in real life, but the bulldog-frog creature, the cobra with a shaggy dog tail and a few other critters do generate a few laughs (probably inversely proportional to one's age or any leftover child-like sense of humor one may possess). Even so, director Brian Robbins ("The Perfect Score," "Hardball") never gets imaginative, smart or clever enough with that or any of the rest of the material to make any of it stand out. And the two storylines (as well as the courtroom scenes featuring Danny Glover as Allen's boss and Jane Curtain as the presiding judge) don't mesh as well as they should.
I suppose if you're a young kid and/or a fan of Tim Allen doing his normal shtick as filtered through canine behavior, this offering might be to your liking. Yet, while the first film is notable for being the first live-action picture Disney ever produced, this one is too forgettable for history beyond being yet another example of filmmakers raiding the film vaults for projects to revamp. In the end, "The Shaggy Dog" is something of a shaggy-dog tail, uh, tale in that it's long, drawn-out and anti-climatic despite the inherent, if limited material.