I always thought SGT`s were more common in male gerbils too, but I`ve read a few posts on gerbil forums about females having them too.
Apparently, these tumours can grow internally too, so I would have her seen as soon as possible SnuggleHam. These lumps can be removed successfully and when the wound heals up, you would`nt know it was there!
Do you think she will be able to go back with the three others once she`s been operated on? Gerbils are notorious for de-clanning and when I ever have to attend a vet (touches wood...!) I plan on taking the cagemate along too to prevent this. I witnessed one of my ill gerbils (now sadly departed) de-clan with his brother within a day of not being able to SEE him because his eyes were caked shut from sleeping too much. I bathed his eyes gently and within hours, he was leaping to attack his brother.
he died during the night and Grub was left on his own.
Two weeks later, I introduced a very young male to Grub, who he immediately loved! I was so lucky to find wee Munchie as a companion after Dibble passed on.
Sorry for rambling on.....I just thought I would mention the seperation thing and how it could/might cause a de-clan. I hope it does`nt. x