But two months ago, her owners found a lump on her leg, reports CBS News medical correspondent Dr. Jon LaPook. It turned out to be a mast cell tumor, a type of cancer diagnosed in almost 200,000 dogs every year.
"It's the kind of cancer when treated appropriately or somewhat aggressively, you can have good successes, but it certainly can progress and kill an animal," said Dr. Karen Oberthaler, a veterinary oncologist.
Up until now, dogs like Stella with cancer have had limited choices. The only options for drug therapy have been drugs developed for humans - not animals.
But t here's new home with Palladia, the first cancer medication specifically developed for dogs, and promising for other pets, too. The drug maker Pfizer said it caused 37 percent of mast cell tumors to disappear and had a positive effect in almost 60 percent of dogs.
Lisa Peterson lost her dog Basha to cancer six years ago. She's grateful to see cancer researchers apply lessons learned in people to pets.
"It's important for all pet owners," said Peterson, who is a spokeswoman for the American Kennel Club. "It shows they are valued family members."
Veterinarians are going to wait and see how Stella responds to conventional therapy before considering this new treatment, but it's comforting to know that there may be another option for her.
"It's got a lot of potential. I think we have good therapies for mast cell tumors but we don't have great therapies," Oberthaler said.