Hi, I've adopted 5 Guineas recently (1 pair and a trio) and of these 4 have had a URI, they sound like they're crackling! They didn't have any other problems no discharge etc...anyway i found if i gave them the antibiotics for 5 days they got better but maybe had a little sneeze, the crackle had gone but occasional sneeze. I've been building up their immune system with good veg and it seems to all be heading the right way...my vet said to only give them the antibiotics for 5 days as after that it's stops working properly. The trio are absolutely fine now and the pair have perked up today so i'm hopeful that i'll be able to put them all together in a week or so!.....i weigh them all every week and this i think is great for spotting problems early, even if they've only lost a little bit of weight they don't feel quite as "solid" when they're under the weather!? What with a neuter, hay poke and 4 URI's this month...not to mention the dogs check up and prescription, my vets have done very well out of me this month!