Identify this YA book series about dragons, acid blood, and dangerously cold nights

I'm trying to remember the name of a series of books about a boy who works with dragons. Dragon's blood (or maybe it was slobber?) is acidic, and the children who wrangle these dragons often end up with deep pock marks. On this world, days are like ours but nights get very cold, requiring anyone stuck outside to find a shelter until dawn (not the false dawn)

The other thing I remember is that in one of the books by slicing open a dragon and spending the night, the character emerged with special dragon powers.