What respirators should be used with mouse feces?

Any respirator will do. Make sure you're buying a "respirator" and not just a mask. The packaging will say "respirator". If you are working in an attic, especially in summer, you'll be apt to remove the respirator because of the heat and discomfort as well as the inability to communicate with others (I know this personally). However, if you do this, you might as well not even wear the respirator in the first place. If you're entering an area that you know contains rodents, just try to get the job done as quickly as you can with the respirator on. I was an electrician and worked in lots of old houses and I got used to wearing the respirator. I was also a soldier and learned the importance of trusting my equipment. A respirator is much more comfortable than an NBC pro mask.