You are here:

Mice/Fatty tissue around neck and shoulders?


Hello, about seven years ago I found two field mice babies crying and blindly looking for their mother. I took them in and raised them, naming them Millie and Margie. Since then, when Margie was about four years old she started getting an abundance of 'fatty' tissue around her neck and shoulders stopping just before her legs. It was soft to the touch and the rest of her body had gotten pretty pudgy, too.  Her sister Millie stayed small and Margie always ate way more then Millie so I chalked it up to her needing a diet. Fast forward to them being seven years old and now Millie has the same situation occurring. She has the same squishy ring of excess tissue around her neck and shoulders. What is concerning me is that her right side (where her shoulder and right arm meet) is way larger then her left. It looks large enough to get in her way when she runs on her wheel. I felt it, pressed on it, and it doesn't feel hard at all. She doesn't seem in pain or upset by me touching it either, but I'm concerned it isn't just fatty tissue since it isn't evenly growing on each side of her. I was hoping this might be a normal thing that occurs with mice that don't get enough excersize and are fed too much but I don't want to pull the wool over my own eyes if she needs help.

Hi Lacey,

This might be a silly question, so please excuse me, but are you positive these are field mice?  Mice tend to live about 2-4 years, with a three or four year old mouse being quite old.  So you can see why I am surprised that they have lived seven years!

Since I can't really be sure what species they are from here (perhaps you could attach a photo?), I'm not sure I'm qualified to offer advice on how to address these lumps at home.  A veterinarian who works with exotics or pocket pets would be able to verify almost immediately whether the lumpiness is fat growth, something caused by aging hormones, abscess development, edema or poor circulation, mammary tumor growth, or anything else.  Once they give you that information, you'll be able to figure out exactly how to proceed without having to guess.  If a vet is not possible, please send me a picture and I'd be happy to do my best to help you identify what may or may not be going on, though again, a vet would be the very best choice.

I can tell you that they do not need a diet, though exercise is always a beneficial thing.  Rodents all control their intake very well, even those prone to obesity, and restricting nutritional intake could cause more harm than good.  On the other hand, however, taking steps to offer the healthiest commercial diet possible and limiting treats can go a long way in limiting stored fat, lowering body temperature, and improving health.

Please let me know if a vet isn't a possibility or if you have any further questions, and I'll do what I can!  Best of luck,


All Answers

Answers by Expert:

Ask Experts




I can answer questions regarding mice as pets, mouse behavior, color and coat genetics, breeding techniques, and general health questions. I can help with caging and setup, nutrition, social issues, and what to do in most mouse emergencies (such as unplanned litters, injuries, fighting, etc.). I can also assist with questions pertaining to orphaned mouse pups, weaning litters, and questions of mating and birthing. I cannot answer questions about exotic or wild varieties of mice such as spiny or pygmy mice. *****FOR EMERGENCIES, anything requiring immediate medical intervention, PLEASE take your mouse to a professional veterinarian or wildlife rehabilitator who works with mice as soon as possible! IMPORTANT RESOURCES: Raising Orphaned Mice: Orphaned Mice Videos: Natasha's Your First Mouse: General Mouse Help: Mouse Info and Exotic Breeds:


I have enjoyed the companionship of mice nonstop since 2004, and spent a year caring for them in a lab where I learned a great deal about their breeding, social needs, and health. I spent a few years breeding them, specifically working with albinos, marked mice, angora mice, and satins. My education never stopped - I am learning something new every day from current and well-established research thanks to the wonderful folks at the Jackson Laboratory, as well as from my wonderful mousey friends online. I also love learning from my terrific questioners here on AllExperts - you folks keep my passion for these amazing animals alive and well!

East Coast Mouse Association - expired, American Fancy Rat and Mouse Association - expired

Partial University for a B.S. in Microbiology, Partial University for a 2-year degree in Veterinary Technology (RVT cert), C.E. classes in pathogens, aseptic technique, genetics, and applications

©2017 All rights reserved.