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My pet rat has a lump near her tail. When should I see a vet?

Updated on September 23rd, 2025

Pet's info: Small Animal | Rat | Female | unspayed | 1 year and 4 months old

My rat Nessie has a big lump near her tail

3 Answers

Most Helpful Answer

Answered By Ricardo Fernandez, DVM

Veterinarian, Veterinary Oncology Resident

Published on August 14th, 2019

Thanks for using Petco Pet Education Center, formerly Petcoach! This may be a benign or malignant growth. This could even be an infection. This cannot be completely assessed just by looking at pictures and usually requires sampling such as fine needle aspiration to determine its origin. Sometimes a biopsy is needed for a definitive diagnosis. I recommend that you have her evaluated by your veterinarian for further assessment and treatment. I am really hoping for something benign. Good luck and have a good day!

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Dr. Strydom, DVM
Veterinarian
Published on July 24th, 2017
Hi there. Sorry to hear that Rosie is having this issue.

Any lump on your pet should be checked by a vet . I can tell you that rats get a lot of tumors so I am assuming it is a tumor. She is at the top of her lifespan already at 2 years old. They don't typically live longer than that.

Here is a link to an article about tumors in rats:

http://www.petmd.com/exotic/conditions/cancer/c_ex_rt_cancers_tumors#

I hope this helps. If you can, get her to a vet for an exam.

Best wishes to you and Rosie!
1Pet Parents found this answer helpful
Answered By Mallori Kaminski, BVSc
Veterinarian
Published on February 21st, 2017
There are a couple of possibilities for what the lump is on Muffin. It could be a mammary tumor, or and abscess. The only way you will be able to definitively tell which it is is to take her to a veterinarian for a fine needle aspirate, where the vet will stick a needle into the lump and look at the collected cells under the microscope. Either way she will likely need surgery to remove it, and there is a chance that it is too big, or in a risky location for surgery. If she is otherwise well in herself then you can continue to monitor her and look for signs of her being uncomfortable. However if she stops eating, drinking, acts lethargic or starts having trouble moving due to the lump then she needs to see a veterinarian as it has become a quality of life issue and she may need to be euthanized.
1Pet Parents found this answer helpful

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