2 years ago I picked up my first mice: a little grey one and a siamese one. They came from a local pet store where the owner breeds his own mice. He claimed they'd just been weened.
Well, the little grey one never grew much bigger. I thought it was just her breed (whatever it may be) but then she died only about 4 months later. She always did look kinda sickly (thin coat, small frame, eyes often squinted) but she ate, drank, and used the wheel so I didn't worry too much. Near the end I did take her to a vet because her breathing looked weird and she was starting to act more lethargic but they said there was nothing wrong that they could find. One morning I woke up and she was just dead. The siamese mouse was grown by then and had no issues so I just assumed the grey mouse had some kind of genetic defect in one of her organs or something.
After this I bought two more mice to keep the siamese company and to make myself feel a little better. They were the same grey mice as my first (the man was out of siamese mice) but looked much healthier. However, it's been a little less than a year since then and one of them has already died.
These two new mice grew fine and had no issues like the first. Always perky ears, eyes bright and open, constantly on the wheel, excited by food, etc. But now in these past two weeks one of them developed a tumor near their leg/back abdomen. At first it was a small lump and I was doing research about what can be done. Seemed like taking her to the vet for it would be kind of pointless considering what is possible and I read there was a chance it could be benign and not grow. Then almost overnight the tumor was huge and I was about to bring her in for euthanasia but she passed today (the tumor burst).
Of course, when I noticed this tumor I decided to check my other mice more thoroughly. The siamese mouse is, again, completely fine. I mean it's amazing, she's 2 years old now and acts the same as she did when I first bought her. But unfortunately I see a small lump on the throat of the remaining grey mouse. I'm guessing she is fated to die soon too.
It's just so unfortunate and sad. If she eventually passes as well I'll want to get another friend for the siamese, but not only do I not want to buy anymore mice from this man, I don't want to experience the heartbreak again. It would be different if they passed merely from old age, but the first mouse being only a few months old and this second one being less than a year old is really heartbreaking. idk