Death of Obese Mouse

Question
Guten Tag, Natasha,
  I am impressed by all of the friendly, excellent answers that you give to so many who ask questions.
  My mouse, Moe, died last week in the palm of my hand while I was trying to "comfort" him. I got him approximately thirteen months ago and he was a black and white fancy mouse with hair that was a little longer and silkier than that found on most other mice. He also had rounder facial features which didn't have the "pointiness" of your typical pet store mouse.
  Moe never liked to run much on a wheel, even though I tried different plastic types. He was kept in a ten gallon aquarium with wooden and plastic toys and houses and I put in paper towel and toilet paper tubes which they all like. (Larry, who I purchased at the same time, is a speed demon on his wheel!) Moe got really fat over the course of the year even though I fed him a good quality mouse food. The Internet articles say that a pelleted diet is better (I know that this is true for pet birds, of which I have twelve) but the mouse pellets seem boring and they don't appear to like them. In addition, I give the mice a little raw oatmeal and some veggies every few days.
  Moe just got fatter and slower and a week or so before he died, he just didn't seem to be able to use his back legs very well. He itched a little, but showed no bald or sore spots. I had to take Moe and Larry to the vet's last year because of mites with ensuing good results, and this itching didn't have the severity of the other time.
  After Moe died, I felt around his body and he had a small grape sized "something" in his right side. Could that possibly have been a tumor or just a fat deposit? It seemed to move with a little pressure. There were no unusual swellings or discolorations on his body. I am just curious if you have had this experience.
  Moe liked to be held (he would run on people's hand and arms and poop to their dismay, but I am thinking that he may have had a heart attack due to stress.
  I emailed you before about the passing of another mouse and you were very consoling with your answer. Having kept parrots with life expectancies of decades, it is a little unnerving to have pets who live for months and not years. Moe is buried in my snow covered yard under a towering holly bush.
  Thank you for the attention to this long letter.

                              Sincerely,

                                Randy

Answer
Dear Randy,

I'm sorry about Moe.  I think you are right that he had a tumor.  It's not unusual for a mouse to get fat on a normal diet, but obesity does not cause difficulty in walking.  And mice do develop tumors quite often.  

I have found that my sweetest mice will wait to be held, or ask to be held, so they are in my hand when they die.  This has happened many times, and it cheers me to know they feel loved when they go.  

Just so you know, I lost a very special mouse a couple of days ago (who was also fat, but healthy, so your letter brought tears to my eyes) to a heart attack.  Her name was Fluff, short for Kerfluffle, and she was a long haired mouse too.  Maybe Fluff and Moe will meet up in mouse heaven.

squeaks of condolence,

Natasha & her horde:

Brandy
Little Honey
Chanterelle
Valentine
Daisy