Q: I am very curious about what the object protruding from this mouse might be. The mouse had been dead for not more than three days when the picture was taken. The strange object does not seem to be coming out of the mouse’s rectum, although I guess it is possible.
A: I appreciate your curiosity….but I’m glad I saw this picture hours before a meal!
My bet is that it’s a bot fly cocoon. These insects begin as a fly-like insect that lays eggs in spots where small mammals congregate. When an animal gets the egg on its skin, the egg hatches and burrows underneath. As it grows larger it makes a big bump under the skin.
Finally the larvae hatches and pushes through the skin. That’s the state at which you found your hapless mouse.
Maybe the trap was the lesser of two evils for this little critter!