Kathy Morison does cartwheels on her birthdays. Round-offs, too, though she prefers a spotter for those advanced gymnastics moves, but she still plans on doing them as long as she can.

But what the 45-year-old Morison does best is juggle.

"I keep a lot of balls in the air," she says with a smile.

It's probably true of any working, single parent – which Morison is – and similarly true of any professional theater person – which Morison also is.

This week Morison opens in the B Street Theatre's new B3 Series production, "The Little Dog Laughed," playing Diane, a sarcastic, cynical Hollywood agent trying to keep her star client's sexual preferences in the closet.

As usual, she's juggling acting and home duties, also helping her 17-year-old son, Alexander, get ready for his junior year at West Campus High School. Morison took a break from an active and varied acting career when Alexander was born.

"It all really had to do with me being a single mom," Morison says.

"I wanted to be a very, very active part of his life while he was in those formative years. To be there for the soccer games, the T-ball games, the whatever."

Morison stresses that former husband Gary Pannullo, a manager at Esquire Bar and Grill, is very active in Alexander's life and that they often attend her shows together.

Before Alexander was born, Morison worked in community musical theater, then moved to burgeoning versions of the Sacramento Theatre Company and B Street's early Fantasy Theatre Company for young people.

A skilled gymnast during her youth in Merced, Morison received a love of music from her teacher-musician mother and a love of competition from her PE teacher father.

"Two things kind of collided in me," she says, and they made her an outstanding musical theater performer.

The late Dennis Bigelow cast her in her first non-singing role at Sacramento Theater Company.

"It wasn't until Dennis told me I could do more that I considered non-singing roles. He cast me in shows that weren't musicals. We did 'Noises Off' there and it feels like it was yesterday, but really it was 18 years ago," Morison says.

Buck and Tim Busfield saw her in a production of "Little Shop of Horrors," which led them to ask her to work with their touring Fantasy company.

"That was really the first Equity contract you could get in Sacramento," Morison says.

When Bigelow left Sacramento for Portland, Morison followed her mentor to continue working for him. But after Bigelow's theater companies eventually folded, Morison came back to Sacramento. She worked a couple of national tours, first with "Sesame Street Live" playing Elmo, then with the musical "Snoopy," playing Charlie Brown's little sister Sally.

Then Alexander was born and she took a hiatus from the theater until B Street called. Buck Busfield asked if she'd be available for their new professional Family Series and she did "A Year With Frog and Toad" in November 2004.

Morison has worked consistently at B Street ever since, mostly in Family Series plays (starring in "Junie B. Jones" among others) and occasionally stage-managing other productions.

She says Alexander has gradually begun to appreciate what she does.

"In the last several years, maybe he's seen me in one too many kids shows and it's kind of embarrassing to see his 40-something mom up there acting like a 5-year-old," Morison says.

Alexander got an even closer look at his mother's talents when she directed the student production of "Grease" at his school last fall. "I think he got to see the different things I can do firsthand when we were rehearsing last year. I would get up onstage to show the kids what needed to be done to create a character. He would see me flip from being Patty, to Rizzo, to Sandy in matter of minutes."

In "Little Dog," he'll see his mother's craft and artistry in a very different context that includes acerbic adult wit and onstage nudity (male characters, not his mom).

"This show will be a total different deal for him," Morison says.

"Little Dog" director Elisabeth Nunziato calls Morison one of the "gamest" actors she's ever worked with. Nunziato also jokes that Morison has supernatural qualities.

"She can fly. When I have a difficult blocking problem I just say 'Kathy, you can make this work because you can fly.' "

Now that she's a B Street company member, it's not surprising that the closeness Morison experiences there means the most to her.

"I've always been attracted to the theater companies that have a sense of family. It's your little niche of where you belong and that's exactly what it is here. We would do anything for one other."

IF YOU GO

WHAT: The B3 Series production of "The Little Dog Laughed"

WHERE: 2711 B St., Sacramento

WHEN: In previews 7 p.m. Thursday and Friday; continuing 7 p.m. Tuesdays-Fridays, 8 p.m. Saturdays; matinees at 1 p.m. Aug. 31 and Sept. 7; 2 p.m. Sept. 4, Sept. 18 and Sept. 25 only.

TICKETS: $12 previews, $25 Tuesdays- Thursdays, $30 Fridays-Sundays, $22 Thursday matinees.

BEFORE THE SHOW: For a pre-performance beverage, adult or otherwise, come to the theater early. Soft drinks, beer and wine are served before the show and during intermission in the theater lobby.

ADVISORY: "The Little Dog Laughed" is for mature audiences. It contains strong language and nudity.

Call Bee theater critic Marcus Crowder, (916) 321-1120. Read his blog postings at www.sacbee.com/21q.