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Pet Rats/Sudden weight gain, biting and nesting


I brought my female rat from a pet store two weeks ago. Up until recently she has been perfectly happy and calm, it is only now that she has started to bite me. I try to touch her- she bites. I can't even change her food without getting bitten. She never drew blood until tonight. I'm not sure why the sudden aggression towards me. I Har been nothing but peaceful with her. She has also gained weight around bed belly area. Her belly is almost running on the ground whe she walks. And she has started to best big nests with her food and water sources. Could she be pregnant? And the biting haut en defending herself because she sees me as a threat to her unborn babies? I'm scared to touch or go near her, I want her back to normal.

Hi Ainsley,
Yes, I would say she is pregnant. Don't worry, her aggression will get less as the babies get older. However, you need to handle the babies every day to make sure they bond to humans and make good pets, even if you have to get her out of the cage first. See the article on Reproduction on my website at on the Rat Info page.

BTW, if she was meant to be a pet instead of snake food, you should complain to the pet store about them selling a pregnant rat. They should keep the males and females separate.

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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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