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My rat has a soft lump under its skin with a brown spot. What is it?

Updated on September 23rd, 2025

Pet's info: Other | Unknown - Other | Male | unneutered

Three of my rats whom I live have lumps on them. They are soft and move but it is under the skin s of late I can see like some brown spot coming on the top of it. There are no vets by me who treat rats please help. Oh they are eating and drinking fine

1 Answer

Most Helpful Answer

Answered By Rebeccah Wood

Licensed Veterinary Technician, Registered Laboratory Animal Technologist

Published on May 9th, 2018

Hi there, and thanks for using Petco Pet Education Center, formerly Petcoach! I'm sorry to hear about your lumpy rat friends. Small lumps (less than 1cm) in the skin that have a brown spot or head on them might be sebaceous cysts - a common condition in male rats where a gland in the skin gets clogged and swells with cheesy, white-yellow material. You mentioned that these lumps are soft and under the skin, however, which makes me think of another kind of lump. I don't see that you mentioned their ages, but if they are older rats (over 1.5-2 years old), I do start to worry about mammary tumors (yes, even in males!). These are extremely common in rats as they age, and may be benign or malignant, and may need to be removed, especially if they get large. I strongly suggest that these boys get evaluated by a vet to determine what these lumps are. There is a vet that sees rats near you - here is their info:

Acacia Animal Hospital
4205 N Campbell Ave, Tucson, AZ 85719
(520) 308-4225

In the meantime, if you'd like to repost with a picture, feel free to do so. I am also available for consultation if you'd like to discuss your concerns further. Good luck, and I hope that Lenny, Norm, Fred, and Herman stay happy and healthy!

2Pet Parents found this answer helpful

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