Every dog owner at some point has faced the following dilemma: Leave the party early or let Spike poop on the Pergo. Ergo, not only is pet-sitter extraordinaire Shirley Mitchell your pet's best friend -- she's yours too. Mitchell, who daily wakes at 5 a.m. and sometimes works until midnight, began creature-sitting in 1987, after throat cancer took her beloved cat, Sammy. Heartbroken, she vowed never again to love another animal. Then a friend, a vet technician, called Mitchell for help: The office had no room for boarding. Could she dog-sit? "She thought I'd find it therapeutic, and I did," says Mitchell, who per day charges anywhere from $25 to $40, depending upon services and location. "Soon, I was getting all sorts of referrals from people, and it took off from there." Flash-forward 16 years: Mitchell has walked, fed, and otherwise pampered not just dogs and cats but fish, turtles, birds, ferrets, and the occasional skunk. She takes pets to the vet and drops them at the groomer; plays with them and takes them for car rides; administers medicines and changes wee-wee pads. Then there are those crazy Malteses: She once had to rock one to sleep; she rescued another after it tangled its leash in a second-floor stair railing and nearly became a fur rug. The bottom line: The woman is trustworthy. Want proof? She's got more than 75 keys to clients' homes on her ring. And she's busy, busy. Which is why squeezing into her schedule is as likely as teaching a gerbil to moonwalk.