American Fancy Rat & Mouse Association

This article is from the WSSF 2013 AFRMA Rat & Mouse Tales news-magazine.


Bloated/Hot/Lonely Mouse

By Carmen Jane Booth, D.V.M., Ph.D.

Melody Gee, Facebook
QI am at a loss. I’ve tried seven vets today, all of which could not help me, not being available, or not knowledgeable on the subject. I have a 9-month-old female blonde/white fancy mouse, Athena. She recently exhibited hunching and slight bloating. She was very tiny when I got her; she is housed alone. It was suggested to feed her a bit of ice cream which I stopped after she got bloated. I contacted a mouse expert of sorts (he specializes in deer mice), and he has been extremely helpful. I also have a medical background. I went to a link that gave me a helpful suggestion of 1 tbsp. of Karo syrup to 2 tbsp. of hot water cooled to room temp. She drank that and within 16 hours she finally eliminated whatever it was that was causing her to not feel well. She was active, alert, hungry, playful, and curious as she used to be.

Her diet is mainly of pumpkin seeds, one chopped walnut, some barley and oats, millet seeds, some bread at times, and once a week a few sunflower seeds. Since changing her diet, I’m keeping a small amount of Karo syrup in her cage (this takes the sweet place of the ice cream I wrongly gave her), she takes more to that water than just plain water. In her water bottle, at all times, is fresh, cold spring. I add at least once a week a powder of electrolytes and protein to her water, to keep her in general good health as told to me by Petco where I bought her.

Last night (4 days after original treatment) she began to show signs again of the hunched over, waddling. She is not hungry and drinks the water/syrup mix willingly but sparingly. I noticed some poop stuck to her fur which may have been impeding her walking and washed it clean. She just wanted to go back into her house.

It was then suggested that I try olive oil or flax seed oil to help if she is constipated but to look into possible megacolon. I don’t think she has this; however, I am still worried. I gave her a small amount of olive oil and 5ml in a syringe of Karo syrup mixed with water then. Within a few hours, she again was running and drinking her water. She seemed better this morning, drinking her water, eating her seeds, and running about, but again walks a bit waddled, and I think it may be that her fur is a bit soiled by her bottom. My dogs used to walk like that after a messy poop but they lived long into their teens in perfect health. So my assumption is constipation. I may be wrong, but I constantly feel her for tumors or an unusually large feel to her intestines, which I don’t feel at all and she shows no signs of distress when I palpate her.

The slight bloating has just about disappeared—it’s very slight and can only really be recognized by me (I’ve had her for 6 months). Her coat is still shiny and smooth, her eyes are clear and wide (she has blood red eyes).

Her problems began before I changed her diet. I keep her on a strict diet now which is why I am baffled at her symptoms. She was, until last week, in perfectly good health. Her environment is the same—I use paper bedding since I know most bedding can cause parasites and respiratory issues in mice. She does have a wheel. When she was younger and smaller, she loved it and for hours on end, she would run. Now I think she may have outgrown it or just prefers to run all around when I take her out of the cage. She still goes on it, but not all night like she used to.

Well, I just examined her again (she was climbing, eating heartily, running fast all over the place, playing with her ball—she stopped all activity when she was bloated), and I found a lot of poop in her house, which I just changed. I think it’s just constipation. We tried to take a pic so I can show you, but she won’t sit still!

The only thing now that may or may not be normal, it is hot and humid today, so she is sleeping on her blanket outside of her house, rather than inside. She does this on occasion but not sure if this is a sign of possible indigestion again. She is not lying prone on the blanket outside her house, she is curled up tail to nose as she would in her house. Loneliness perhaps? Not sure.

I am desperate for any other suggestions and would appreciate any feedback you have on how and why this happens and any other treatments!We love her dearly and would very much like to see her live content and as full as possible. I do not breed them. I’m just a pet owner and animal lover! Thank you!

Answer by Carmen Jane Booth, D.V.M., Ph.D.
APictures or videos would be a help. Old mice with the hunched look are usually dehydrated. The bloated abdomen is often an enlarged spleen which is often lymphoma.

It is seen in dogs and cats with a large intestinal parasite burden where they are losing so much protein (starvation), that they have the lax abdominal muscles and the protruding abdomen. We don’t see this in the fancy mice.

Pet store mice have mites and pinworms. Fresh fecal pellets can be submitted for a fecal analysis for intestinal parasites. Anal tape test for pinworms. Although we are using PCR for pinworms and fur mites in addition to fur plucks and fecal analysis.

Megacecum or megacolon is due to a developmental problem with intestinal neurons and would not resolve with Karo syrup. The sugar water probably helped relieve the dehydration and added some calories. Mice have such a high metabolic rate that if they stop eating or drinking for any reason, they can decline rapidly. A good physical exam would be able to tell if the mouse had lymphoma or megacolon, but the veterinarian would have to have mouse experience. In most cases, megacecum/megacolon would be congenital. However, it could happen from loss of the enteric neurons or ileus from unknown causes. This happens in cats, and I have seen it in opossums.

Uterine cancer will give a bloated abdomen appearance. I have seen many mice that had enlarged abdomens and most were cancer.

The diet you are feeding is nutritionally deficient in many key areas. This mouse needs a normal diet. Mice will eat just about anything. I would do a dry dog food that has grain in it if you can’t get a proper mouse block diet. A good rodent chow and water with the whole grains as treats would be fine. They don’t need the sugar water.

Answer from Karen Robbins
ASometimes old mice will have these symptoms and euthanasia is the best for them because of their age. In my experience, it could also be caused by something like a tumor or a failed pregnancy where the babies are retained.

Regarding her diet, seed mixes need to contain more than what you are using to give them everything they need (see Make Your Own Mouse Seed/Treat Mix for a mix that has a balance of items that can be used as a treat or main diet). A high-quality lab block such as Teklad or Mazuri (found in some pet shops/feed stores) is the recommended diet as these contain everything a mouse needs in the right proportions, and then giving them treats of oats, millet, whole grain bread, dog biscuits, pumpkin seeds, canary grass seed, etc., will ensure a healthy mouse. If you are not able to get lab blocks, then the seed mix we have on our web site or a mix listed on the FancyMice Breeders forum are the recommended alternatives. Water should just be plain fresh water (my mice get filtered water). You won’t need to add electrolytes or protein to the water or give her sugar water as she will be getting a balanced diet. Also, a mouse will stop eating if it is dehydrated (Empty Mouse Water Bottle).

Mice (nor rats) can take the heat so that is why she is outside her house during the hot days. We have an article on this Mice Survive in Heat? as well as things to do to keep the rats and mice comfortable on hot days Tips For Hot Weather.

Regarding your question on loneliness, yes, female mice need to be in groups (preferably 3 or more) as they are social animals. The males, however, don’t get along with each other like rats do and must be kept separate or they fight (sometimes as soon as 4 weeks), and will injure or kill each other (see the following articles for more: The Mouse of the Day, or Male Mice Getting Along). Sometimes males will get along for a while (the English show mice are more calm) but I’ve found they will eventually start fighting at some point and need to then be housed individually. I have heard of a couple people that had males live together their entire life but it is not the nature of male mice to get along like this.

A wheel should be at least 6 inches in diameter for mice. The most common reason a mouse will stop using a wheel is because it is too small.

Sounds like she really enjoys her playtime outside her cage. Since you have her by herself, you may be interested in maybe teaching her things in addition to her having playtime out with you. There are a couple sites that go into agility and other training for mice.

Let us know how she is doing.

QUpdate: WOW! What a lot of valuable info!!! First I want to say that Athena has improved greatly! I have been keeping a diligent eye on her constantly since she is up during night hours. She has been in her general good health for one week now, but I would feel much better with another week seeing her just like this.

She went back into her house once the air conditioner went back on. I so much want to train her, but more importantly I want her to live a pretty long, happy, and healthy life.

Once she is out of her cage, she is running and climbing so fast I have to stay directly on top of her (her activity level has returned to when she was younger). She is running around the large couch, in and out of her blankets, tubes, and other toys I have for her. And when I do put her in the cage, she turns around fast and hops back into my hand for some more.

My two males, Phoenix and Pegasus, died recently of rodent dermatitis. They were all housed separately. The boys began fighting the moment I got them home. So it was off to separate cages. I lost the boys far too young and it really broke my heart, which is why at the very moment of Athena’s illness, I knew I had to reach out to mouse communities.

Since no animal can speak, it is the job of the owner to put the puzzle together. I had gerbils and hamsters before, all which lived out a very happy, healthy, and long life. Fancy mice are new to me, but I know from working with animals she wasn’t feeling well.

I am extremely hopeful that this is not a form of cancer. She is eliminating herself regularly and her appetite is very healthy; however, she is finicky and when she is done with her food, she will cover it with bedding and snub her nose to it! So I’m never afraid of her overeating, plus I am careful not to overload her food dish. I did just add small dog biscuits, which I think she buried somewhere in her cage last night. I did try fresh vegetables or fruits—she turned away all of them, unlike the boys. The boys loved fresh fruit and vegetables but she never did. I do give her most of the diet you have suggested, and I think it was indigestion along with constipation due to the ice cream. I am going to add the canary seed grass. I am also going to look into lab blocks. It was suggested by another breeder that as she gets older, I can use a cuttlebone like they use with parakeets. I keep wood blocks in her cage as well to keep her teeth size low, which she does chew on.

Do you think it’s too late to introduce another female? I’d rather not, but I just don’t like her being lonely, even though I keep her busy playing and exercising when she is out of the cage. She is very territorial of her house, so I can’t go near it without a little nip from her sometimes.

Thank you so much for the articles, I am a better mouse owner because of it! And I won’t feed her too much of the electrolytes! She has taken to her new diet and loves it!

Her ears are up and perky; she is always inquisitive of new things as well as old. With all your help, I can almost count on her living a full, healthy life for at least another year since she is only about 9 months. She has the sweetest personality, and the boys had their own unique personality as well. She has beautiful markings—white star on her forehead, white band around the belly, white paws and white under her neck. The boys were striking as well—black and white.

I really can’t thank you enough for all this, this is much more than I had expected. Athena thanks you as well!

AIt depends on the mouse as to how it would take to new additions, especially at her age. The pet shop mice can be more territorial and aggressive towards other mice. If you wanted to get 2–3 new ones, you could try introducing them on neutral territory (somewhere Athena doesn’t go) and see how she would react to them. If all goes well, then thoroughly clean and disinfect the cage they will all be living in (including all toys, houses, dishes, wheels, water bottle) and put in fresh bedding, food, water, and treats, and place everyone in the cage. If she attacks them and draws blood, then she will need to be taken out and maybe a couple hours later try putting her back in with them. If she refuses to get along, then you will have to have two cages of mice. Karen Robbins

Update: Athena continues to do well and is active, alert, and as sweet as ever! Much to my surprise, she does like a tiny piece of watermelon, which I gave her last night. She loves the Karo syrup, and I still keep a tiny amount in her cage.

I was able to get a few pics of her; of course I think she is beautiful! She is a bit wet in the picture as I had just washed her up a bit.


I have now trained her as of last night (with very few tries) to roll on some tubes, go in and out of tubes, and walk on planks. She knows how to give mouse kisses, but that she just did on her own, and will fall asleep in my hands.

And again, I thank you, your organization, the staff, the vet, had it not been for other mice lovers, I don’t think I could have saved her. Thank you ever so much!!!

Looks like Athena is a Lilac Banded or Belted (like Banded but with a narrower circle of white around the body) with extra white spotting—very cute! Sounds like she is enjoying learning new things. Karen Robbins *

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August 13, 2015