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Pet Rats/Pituitary tumor


Hi Debbie

So I messaged you recently asking a question about my rat Possum. She has just undergone an operation to remove two mammary tumors. She's two years old.

Yesterday I noticed she wasn't her usual perky self- she is back with her cage mate Luna. She was a bit wobbly and weak looking. Now my last rat Merlot had a pituitary tumor so I guess I immediately started looking for the signs. And sure enough, she's not holing her food in her front paws, preferring to balance it on the floor or against the side. Her motor skills are not as good- if I tip her paw back, she doesn't correct herself as quickly as she should. She is also not eating as well- harder foods are a struggle, she seems to drop a lot out of the side of her mouth.
Now do you think I'm just looking for this because my old rat had it? I didn't think pituitary tumors were that common. Could it be something else? An ear infection?
I have some Prednisolone 1mg tablets left over from when I was giving Merlot steroid medication- which really helped her for a little while. Do you think I should put Possum on a course of this and see if her motor skills improve? I was giving Merlot 1/2 tablet daily but upped it to 1 tablet daily as the 1/2 didn't seem to have any effect at first. Is that a good dose or would you suggest something different?

Sorry for the long message. I'm devastated that I've noticed these symptoms as she is only just recovering from her mammary tumor operation and I was so hopeful that it had potentially given her much longer.


Hi Sam,
Unfortunately, pituitary tumors are very common in older unspayed female rats (about 1 in 5), so you are right in suspecting that Possum might have one. So yes, start her on the prednisolone, 1 mg lb twice a day to see if that helps.

How long ago was her tumor surgery?

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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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