rat passed

Question
Almost two months ago I bought two rats, Cobalt and Callie.  Cobalt has always been the outgoing on and Callie the shy baby.  Callie got sick, or perhaps trauma, and we had to put her down Wed night.  I did bring Callie back home and let Cobalt see her and Cob's tried to get her up to play and such; I hope this helps her to understand Callie is gone.  My husband and I are both gone the majority and we don't want Cobalt to be alone all day; though we have her out a lot at night.  We did go get a baby, Lily, and Cobalt seems to like her.  Cobalt has still been acting different.  Not quite as energetic, eatting still but not with her normal piggyness, cuddling more.  I expected all these things and know she misses our Callie girl.  I'm giving her lots of extra and special attention and we are just starting to let her roam around the house more, which seems to perk her up.  I was wondering how long this would go on before I should start worrying?  I hated having Callie sick, she didn't seem in pain but she swelled in the head which caused very heavy breathing; I just can't stand the idea of them hurting.  I have some antibiotics from Callie, we went to the vet the day after she stopped playing but had to put her down the following night, should I give those or call the vet about that?  I just want to make sure I give Cob all the support I can. Thanks!

Answer
I am very sorry for your loss. How old is Cobalt?

I would suggest getting another rat close to her age to keep her company.  Rats can mourn to the point they become ill themselves and sometimes they pass on just shortly after losing their cagemates from the stress depleting their immune system.  Its a heartbreaking thing to see a rat mourn their cagemate. Sensitive rats will have a harder time than the more independent rat so it really does matter as far as the rats personality.  If she is not perking up in a few days I would consider another cuddle friend.