A trip to the vet confirmed the worst. She has a very large, fast-growing mass in her belly. This was doubly upsetting since she had been to the vet just two weeks ago for a well puppy visit. The vet couldn't feel the mass at that time. In just two weeks, it grew to the size of a baseball and Winnie lost two pounds. Given the aggressiveness of the tumor, we have chosen not to pursue surgery.
We are just trying to help her--and us--enjoy what time is left. The vet gave her some meds that are helping her feel better. She seems more comfortable and doesn't seem to be in pain.
She's still eating (and eating the best food ever, I must say), going for walks, playing with her tennis ball (which is now allowed in the house), wagging her tail, enjoying getting pet, and barking at the neighbor. However, we know this will likely go quickly and we are heart-broken.
She's a good dog. Yes she is.