See Spot Run
Set in New Jersey, a mailman, Gordon (Arquette), seeks the affections of a hard-working single mother (Bibb). Unimpressed by his constant wooing, she is suddenly forced to give him responsibility over her young son, James, while she's away on a business trip. Gordon takes the job happily.
Meanwhile, an FBI drug-sniffing dog, placed in the witness protection program, has escaped his protective boundaries. With the local mob boss after him, the dog accidentally becomes adopted by James, and ultimately Gordon, who doesn't have much affection towards dogs.