Merry the Mouse has a tumor

Question
Hello! I've read through your answers regarding tumors. My little Merry got a tumor, which grew rapidly. I was not able to get her to a vet in time (she is my first mouse), and wasn't educated, and the tumor grew. Now it is quite an impedment to her, and she is clearly depressed (she is over 2, and though she lives alone, I have built quite an impressive home for her, and am able to spend lots of time with her, so she has been quite happy, sociable with me and my friends, hoppy, and chirpy. She's an amazing mouse - like a small dog). She no longer desires to run in her wheel, and when I return her to her cage, she no longer wilingly steps off my hand - she seems to really want to stay with me.  She also doesn't really want to eat unless I hand her the food - at which time she'll eat freely. I think her tumor has caused her depression. Little Merry has been a surprising delight to me (and my dog) though, and I'm wondering how long it will be until she passes on her own.  I do not want her to suffer, but the decision to euthanize is also heartbreaking when she is otherwise healthy and able-bodied. Other than this wicked tumor, she is quite healthy - still cleans herself and drinks (again, seems more frequent when I am around to coax her).
This tumor is about half the size of her entire abdomen - it's very large. She is my first mouse (and will be my last because this is too heartbreaking), and I just don't know what to expect, and above all wish to ease her suffering/depression. Note: I know it's ill-advised to keep a mouse alone, but I have dedicated a lot of time to her, and she has always been an absolutely happy little delight. She has never exhibited depression until just the last few days. I'm wondering if she's nearing the end - which I hesitantly hope because she seems so sad...
Sorry for the length of this. You're like a mousy therapist.

Answer
Dear Lace,

Poor little Merry! Tumors are so tragic. Mice can live a long time with a tumor if it isn't compromising any bodily functions. It can also kill them quite suddenly. Another possibility is that it might open up and cause her infection. As for getting to the vet, there's nothing to be done about mouse tumors. Mice and rats get a different kind of tumor: Rats can be operated on, but if a mouse survives an operation, the tumors come back quickly.

For me, the important thing is whether she is still enjoying life. If she is really depressed, euthanizing might be the best choice. When a mouse with a tumor is still chipper and doesn't have a problem eating or getting around, I say to wait. But if she is clearly unhappy, and doesn't eat on her own, maybe putting her to sleep would be the humane choice. Although in this society we flinch from euthanizing humans, often a person actually wants to die when they are miserable. The only thing she has to live for is to be with you. And in fact stopping eating may be her way of saying she doesn't want to survive.

As I said, the only thing she has is you right now. What this means is as long as she is alive, you should have her in your hands as much as possible. As much as you can, just hold her while you are doing other things. Perhaps you can fashion some sort of a sling to keep her by your neck.

I'm sorry about little Merry. Most mice actually don't get depressed with a tumor. But you are certainly right. If she can wash herself, she could eat on her own; so if she isn't doing that, it's depression.

Squeaks of condolence,

Natasha