So—here’s the backstory. I have four rats, Bean, Peanut, Pancake, and Pistachio. The latter of the three are all younger (about three months old) Recently I’ve noticed that Pancake and Pistachio have been making this cooing sound; almost like a pigeon. Not all the time, but sometimes, and I know that this can be a sign of respiratory problems. They seem to be eating fine and have had bounds of energy, even after we put them in a quarantine cage. I’ve also not noticed any sneezing or mucus from anywhere. My older rat Bean had to get his teeth trimmed at the vet today, so a few days ago we called up the vet and asked if he could take a look at the babies while Bean was there. He obliged. We took them to the vet, and he listened to their breathing, and felt them over. All that jazz. He even heard their noises. He said that they are fine, but should I still be worried? I should note that my veterinarian is older. If it’s not a respiratory problem, what could it be?