Mouse Has Problem With Its Ears

Why would a mouse’s ears be red and leak a clear fluid?

Q: My daughter has had two female mice we purchased from the local pet store. They were both healthy for months, but just in the last few weeks, one of them has developed a condition in both ears where there is a clear fluid leaking from them and both ears are red and look like there could be some scabbing, maybe from her itching them? She doesn’t have a balance problem and acts normal. I can’t tell a lot from day to day on whether it’s getting better or worse, as she moves around so much it’s hard for me to get a good look. I’ve read some articles online about possible causes, (mites, but I can’t see any; and fungus, but I’m not sure of this either. I clean their cage one or two times a week to keep the odor down).

I thought that if it the cause was mites or fungus that the other mouse would surely be displaying the same symptoms by now. And in case of allergic reaction to food, I’ve also kept them on a diet of only mouse pellets, occasional oats and cheese only as a treat every couple weeks. I’ve also changed from a possible nickel-plated water bottle tip to a plastic cup of water that is changed daily, in case of allergic reaction to nickel.

Based on all of this, do you know what the problem might be? I’ve heard of using mite powder (the kind you use on birds), but I’m not sure that mites are the problem because the other mouse doesn’t have any of the same problems and is perfectly healthy. I also can’t find mite powder for birds; I’ve only found the liquid kind that you spray on them. I didn’t want to spray the mouse with anything that might cause her more problems. Please send me any advice you may have. Thank you for your time.

Q: Without seeing your mouse, it is impossible to say exactly what is going on. This could be parasites, a bacterial skin infection, a fungal skin infection, a contact dermatitis, a genetic condition or something termed ulcerative dermatitis.

From your description, it sounds like it could be the disease called ulcerative dermatitis (sometimes called necrotizing dermatitis). There is no definite cause or treatment for this condition. It causes the ears to be painful, scabbed and red, and a serum (clear fluid) leaks from the skin around the ears. This disease is confined to the skin (pinna) around the ears. There may be a genetic, immune reaction, and/or food related cause to this disease.

The only way to make a diagnosis is for a veterinarian to remove some of the skin near the ear and look at it under a microscope. Treatment is also difficult. We will try antibiotics for secondary skin infections. We will try medication to decrease the inflammation in the skin. We will also give medication for pain relief. Some have tried increasing the amount of vitamin E in diets. There are certain strains of mice that this condition is more prevalent in, and most of those are strains found in the laboratory setting, not in the pet trade.

To best help your mouse, find a veterinarian who has a special interest in mice and can make a diagnosis and administer the correct medications.

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Critters · Mice and Rats

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