I don't actually own rats myself but my girlfriend does.
Her cherished girl Cherrie is currently struggling to breath. She has been making weird noises but we didn't realise anything was wrong. I did ask one other rat owner who I assumed knew more than he obviously did
We bought rats from where he works at and he had given us advice about them. He told us rats could be very vocal. She's now opening her mouth to breath and her noise has what we
think is mucus at it. I just searched in ratforumuk and found here so any advice is great.