Our rat bit her own paws off!

Question
About a month ago, my daughter's pet rat (2yrs old) developed a large, soft lump in armpit area.  Our vet tried to drain it but nothing came out.  Otherwise, the rat seemed fine.  Then, about 2+ wks ago, we came home to find she had chewed off all her digits on one front paw and one on the other.  We thought perhaps the dogs got in the room with the rats' cage and scared her.  The vet gave her a shot of steroids and antibiotics.  The wounds appear to be healing.  Now, after returning from a 2 week trip (someone was here daily to care for the rats), we were alarmed to see our little rat wasting away.  She looks half her previous weight! Any thoughts?

Answer
Does she still have the lump in her armpit?  This tumor in her armpit area is NOT something that can be drained. It is a mammary tumor and should be surgically removed, which I hope you tell me that it was removed by the vet.

Let me know if she still has the tumor before I continue on.