I had a mouse (Shelley) who developed a tumor. I noticed it the day we moved into our new house... it started so tiny but it grew fast. The vet I took her to agreed that she wasn't in any pain, but when she started to show signs of being in pain it would be time to have her put to sleep. She was such a sweet girl. She ended up passing on her own, before she ever showed any signs of being in pain.

Good luck with Tia. I hope and pray she remains pain free and happy for a long time.

Crystal