Cavanaugh was born to Rheta Mason (née Sharky) and Waldo Eugene Sandberg. She graduated from Layton High School in 1981. She first attended Utah State University, then the University of Hawaii, where she met her future husband, Kevin Cavanaugh. The couple married in 1985 but divorced in 1988.  In 1991, Cavanaugh voiced Gosalyn Mallard, the title character’s adopted daughter on Disney’s Darkwing Duck as well as the voice of Chuckie Finster on the Nickelodeon cartoon Rugrats and later, in 1994, the voice of Oblina, one of the three main monster-students on Aaahh!!! Real Monsters.

Cavanaugh could also be heard on The Critic as the voice of Marty, Jay Sherman’s son. Her voice credits also include the animated series Sonic the Hedgehog, 101 Dalmatians: The Series, Hercules: The Animated Series, The Powerpuff Girls, The Wild Thornberrys, and Recess, as well as the voice of Birdie in McDonald’s commercials. In the early 1990s, Cavanaugh also served as an announcer for The Disney Channel for “coming up next” bumpers.

In 1995, Cavanaugh lent her voice to the live-action film Babe in the starring role of Babe the Gallant Pig. She was offered to reprise her role for the sequel, Babe: Pig in the City, but decided against it and the role was instead played by her Rugrats co-star Elizabeth Daily, who voices Tommy Pickles. Also in 1995, Cavanaugh started doing the voice of boy-genius Dexter in Dexter’s Laboratory, which began as a short under Cartoon Network’s What a Cartoon! show and later became the first short to be adapted into its own series for Cartoon Network. She later won an Annie Award in 2000 for her voice performance as Dexter in the hour-long TV special Dexter’s Laboratory: Ego Trip.

Cavanaugh also guest starred on several TV shows including Salute Your Shorts, Cheers, Empty Nest, Wings, The X-Files, Everybody Loves Raymond, and ER, and had supporting roles in the feature films Soulmates and Jerry Maguire. Cavanaugh abruptly retired from voice acting in 2001 and returned to her native Utah; she cited as her reason a desire to spend time with her family. After her retirement, she was replaced by Candi Milo as the voice of Dexter and by Nancy Cartwright (her co-star in The Critic) as the voice of Chuckie in Rugrats.  Cavanaugh died on December 22, 2014 at her home in Cedar City, Utah at the age of 51 of undisclosed causes.