Jay I know you've had another of your female rats very ill recently so it's possible it's something going through your rat colony. Respiratory issues, whether it's a rat or a human, tend to hit the young and the elderly the hardest. I don't have much to offer other than to support the mother as best you can so she can feed whatever babies will survive. I don't know if there's anything you can give her that will go through her milk to them. Your vet (or one of our vet techs here) will likely have that answer.