I’m going to Home Depot soon to get something to deal with the mouse droppings–or, rather, something to deal with the mice. The mouse droppings made me realize that “mouseshit” isn’t slang for anything. When people are insane, they are batshit crazy. When someone who is not normally crazy gets really angry, s/he goes apeshit. Then there is bullshit in the corporate and political arenas, which Harry Frankfurt explains very well. It’s time for mouseshit to enter the lexicon. I am mouseshit scared, I think.
etymoloblog 
From personal experience (my unfortunate dealings with bats are numerous), I'll say that bats have a presence – or a physiognomy, at least – which warrants a term. Their guano may have its own powers and properties, but their faces and wing-claws make me scared. Maybe mouse scat deserves its own word, but it may have to be a level lower on the alert level than bats. Or a level cuter…The irony, now that I think of it, is that bat shit and mouse shit look almost identical. Maybe that will be essential to the definition: batshit crazy and mouseshit scared are two states which, while they appear almost identical, are quite distinct in origin. I thoroughly enjoyed this topic.