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Pet Rats/My pet rat has a weeping tumor


QUESTION: Hi. I have written before about my rat eve, who has since been put down :(. Now my other rat, nellie has a small tumor (about the size of a kidney bean) that has opened a small amount. It weeps, it seems, when she moves around a lot (when playing for example). We have antibiotics from the vet to prevent infection but the lump doesn't look like it will ever close up. She seems fine in herself apart from occasional quiet spells that could be accounted for by her age and lack if companionship since eve died. When it weeps I dab it with damp tissue and let her clean it further by herself. Do you have any advice regarding whether it is inhumane to keep her alive like this for much longer? I am finding it hard to judge considering she is still eating, drinking and coming out to play with me.
Thanks so much xx

I do not think she needs to be euthanized as long as she is behaving so normally. Most tumors do not seem to cause rats any pain or discomfort. Where exactly is this tumor? What color is the fluid that seeps from it? I'm wondering if it might be mammary cancer.

---------- FOLLOW-UP ----------

QUESTION: Hi. It is on her side (where eve had mammary tumors). The fluid seems to be blood, or blood that appears slightly diluted with maybe a clear liquid? It hasn't seeped so far today. It is usually only small amounts that she deals with calmly herself.
Thanks :)

When you say on her side, like under her arm? Because that would be the closest place to the side where a mammary tumor is likely to grow. You might want to read the section about malignant mammary tumors in the Tumors article on my website at Cancerous mammary tumors can often be successfully treated with tamoxifen. I also have someone trying a high-fat diet to treat mammary tumors because the tumors appear to only be able to use sugar, not fat, so the diet starves the tumors. Let me know if you want to contact her.

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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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