Your mouse is adorable!! What is his name?
As far as whether he is sick or not, have you noticed any signs of illness like lethargy, not drinking/eating, any diarrhea? Does he do all the normal things such as grooming/playing, things like that?
I am not sure what would cause a mouse to suddenly look like he gained a large amount of weight in just a few days, unless he is bloated for some reason, or if it was a girl mouse and she was pregnant.
Have you noticed anything out of the ordinary aside from the quick weight gain?
As far as whether he is sick or not, have you noticed any signs of illness like lethargy, not drinking/eating, any diarrhea? Does he do all the normal things such as grooming/playing, things like that?
I am not sure what would cause a mouse to suddenly look like he gained a large amount of weight in just a few days, unless he is bloated for some reason, or if it was a girl mouse and she was pregnant.
Have you noticed anything out of the ordinary aside from the quick weight gain?