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Pet Rats/Pet rat with a bleeding tumor


Hi. My rat nellie has had a mammary tumor for a few months now. It opened for the first time in July and at first scabbed over. Now though, so much of the tumor is viable (a circle of about 1.5 cm diameter) that it remains open all the time. I has started bleeding quite regularly. I usually clean her up and then she sorts herself out. Her behaviour is not different - she is eating and playing as normal. She is a bit less active than she was but that is only because she is 2 and a half years old now. Do you have any advice? She doesn't seem to be in pain as when I clean the area she doesn't flinch. The tumor is about the size of a large grape. Thanks :)

Hi Lu,
Sorry for the delay in my reply. Can you send me a picture? Is the tumor near her vulva? If so, then it is likely to be a malignant mammary tumor, which can be successfully treated with tamoxifen. See the article about this topic on my website at

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Debbie Ducommun


I can answer any questions about pet rats, but you will probably be able find answers to simple questions more quickly on my website at If you have a life-threatening emergency you can try calling me at 530-899-0605. I am not usually on the computer on the weekend.


I have been "The Rat Lady" since 1985 and am recognized as one of the world's experts on pet rats. I have 3 published books and already answer lots of questions about rats daily.

President of Rat Assistance & Teaching Society

I am a monthly columnist for Pet Business magazine, and my writing has appeared in other magazines. I have 3 published books.

BA in Animal Behavior

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