How to Spot a Sick Mouse


We all get sick from time to time, and this includes our pets. Even tiny little mice can get sick too, although it can be harder to tell.

Mice are mostly nocturnal creatures that are highly active—females in particular— and will often disguise their ailments so predators don't see them as weak or easy to pick off.

However, illness includes everything from very minor allergies to full-blown cancer. Mice are very much like humans, so many of the illnesses we suffer mice can catch too. So remember, if you have the flu, salmonella poisoning, unexplained vomiting, norovirus, or other contagious illnesses, then wash your hands thoroughly, avoid sneezing around the cage, or even better remove the cage from your room and have a family member or friend come round to care for your animals. Mice can in fact die from influenza; if their tiny immune system can't fight off a human sickness, it can kill them. Illnesses like salmonella and (in particular) norovirus can kill humans.

Mice don't vomit, but can have severe diarrhea. Dehydration can kill a mouse or other rodent in less than 48 hours!! And mice do not have the same complex minds as we do, they can't be made to understand that if they have diarrhea they need to drink and keep themselves hydrated. More than likely, a mouse will not eat if it is ill.

Here are some common illnesses of pet mice, with their symptoms, treatment, and prevention.

The Common Cold

Colds in mice are very similar to colds in humans and often clear up by themselves. The symptoms include sneezing, watery eyes, shaking, and tiredness, much as in humans. Make fresh food and water available at all times, and keep the cage clean and as dry as possible. Keep the cage out of drafts, sunlight or high temperature. Make sure it is at a constant comfortable temperature for your mouse; not too hot, not too cold. A cold usually clears up in under a week, but if the mouse seems to be getting worse, or there is no improvement in three or four days, then I would go to the vet, as it could be a more serious problem.

Salmonella Poisoning

Mice are highly susceptible to food poisoning as we well know. So make your sink is clean when you fill up water bowls or bottles for your mouse; fill them BEFORE you wash a raw chicken in the sink or otherwise handle raw meat. Thoroughly rinse the bottle with hot water each time you use it. Do not handle food or water (this includes the outside of the bottles as they may touch or lick them) or touch your mouse until you have washed your hands with anti-bacterial soap and hot water for at least a minute or two. This is for your own safety as well as the mouse's. Do not touch cage bars either; we know mice touch and lick them constantly, so infection is easily spread. Symptoms include diarrhea, shaking, dehydration and loss of appetite. Diarrhea can show up as moist, off-color poops instead of the usual dark poops. If this infection does occur, force your mouse to drink as much water as it can, carefully, using a small eyedropper. Do not leave the mouse unaccompanied, it helps to reduce stress if a loving owner is there to support him or her. None of us like being ill alone.


Diarrhea is a common problem, usually deriving from stress, too much fresh food, salmonella, ordinary upset stomach, or the final clearing of constipation. It is very common in older mice. It is nothing too serious, just make sure your mouse is getting plenty to drink; as I mentioned above, you can use an eyedropper to force it to drink. Dehydration causes death in hours, so be careful. Diarrhea is not usually vet-worthy and can clear up easily on its own; however, if it persists for more than a day or two, go and have it checked. Keep your mouse in conditions as clean and comfortable as possible. Be sure plain, fresh food and water are available at all times. Rest is needed.

Skin Allergies

This does not include mites (see below) as they are not an allergy. Skin allergies are another common problem easily solved with extra care. Often mice will have an allergy to bedding, such as certain wood shavings, usually ones bought from pet shops. These shavings can be dusty and may have been sitting for long periods, or if they are really cheap they might not have been treated right. Mice can get allergies from some dry meadow hays and dusty hays, which can irritate eyes and cuts as well as skin. Mice can have food allergies too: vanilla (if used in the water or cage), hamster feeds, fresh foods and herb-based foods are the most likely to cause allergies.

It is easy to spot a skin allergy. Signs include:

  • baldness
  • excessive scratching (other than grooming)
  • rubbing against items in the cage
  • outbreaks of redness, swelling or clusters of bumps
  • high stress levels
  • obvious discomfort
  • bleeding scabby skin
  • tiredness

These can happen even up to a week or so after using a new product. Remember, don't use more than one new product at a time. If you are changing to a new type of feed, don't go out and buy loads of different treats, because if an allergy breaks out again after several days it will be hard to tell which product caused it. The same with bedding: use an older supply up when changing bedding, so you are using one new thing at a time, and you can locate the source of any problem and bring it under control. The same with cage cleaners. You must be careful to only use small-animal cage cleaners such as Johnsons, as they can be wiped off easily, and be sure to rinse thoroughly because over months or years even appropriate cage cleaners can cause allergies on the skin! If anything causes even a small reaction in your pet, discontinue using it. Although even if your own mouse is allergic to it, it's possible a friend's mouse or hamster can try it out.

Treatment includes bathing the area in a warm water and salt solution, using a piece of tissue or a cotton bud. Do not bathe more than twice a day as this can make the skin dry and cracked. Don't bathe the whole mouse, just the affected area. Try to dab the mouse as dry as possible afterwards. Don't leave a mouse to sit wet and cold to dry off; this includes eyes and ears. If the mouse continues to scratch, clean out the whole cage and make an appointment at the vet's; it could be mites. Be careful to monitor the mouse as cuts on the skin can become irritated or infected. Ointments are available but often they are too strong and not much use; they can make things worse. I recommend salt water solution, it is safest for your pet. In rare cases, extreme allergies can cause death. If you suspect your mouse has a serious allergy that is not clearing after a few days—bear in mind that it can take a few weeks for fur to grow back and cuts to heal—better go to a vet.


Mice are prone to getting mites. They usually come from damp dirty bedding, such as wood shavings that have been left outside or not cleaned out regularly. Also wash your hands before touching your mice, if you have been outside in the grass or touching other animals because you can transfer mites to your pet with your hands. The symptoms of mites include:

  • excessive scratching (other than grooming)
  • fur loss
  • loss of appetite
  • raw or cut skin
  • scabby skin
  • mites visible in fur (back and ears are the most common places)
  • mouse appearing distressed
  • mouse rubbing on toys
  • aggressive behavior or other behavior changes
  • looking to be picked up constantly

Go to the vet to have mites checked out. You can treat mites with ointments (make sure you finish your course of treatment) and by cleaning the cage thoroughly each day.

Eye Problems

Often mice will get the odd runny eye, a small amount of discharge or squinting which comes and goes fairly quickly and never needs treatment. However, swelling, crusting over, or white lumps on eyes can be a sign of severe infection and the mouse turning blind. Be aware that there are other more common possible explanations for a runny eye: stress, anxiety, something caught in the eye, or an allergy. The best way to keep these problems at bay is to keep the cage clean, keep your hands clean when handling the mouse, check your mouse daily and if symptoms keep occurring or get worse, go to the vet's. This is easily sorted out with treatment and rest, but sometimes blindness is the result, so get the problem checked if it keeps happening or gets worse. Discharge can come in different colours: clear, white, yellow, green, orange, and red. A watering eye could just mean that the mouse is tired.


Mice are prone to tumors, especially old mice, feeder mice, and mice in poor health. Most commonly these tumors are benign fatty lumps on the sides of the mouse and around its back end. You will be able to see and feel them; they do not go down when the mouse stretches. Get them checked. If they are cancerous, there isn't much you can do. The chance of a mouse surviving the operation is less than 50%, as drugs, stress, infections and recovery are very hard on a tiny mouse, but the choice is up to you. Benign fatty lumps are usually not a problem, and often a vet won't operate on them. But get them looked at just to be safe.

Kinks in Their Tails

If you have a mouse that has a kinky tail, the possible explanations are rough handling in early life, injury in a fight, spine problems, genetic kinks, or having had it trapped in something like a door, a cage ladder or a toy. Kinks are harmless unless the mouse displays problems with walking or balance. Nothing can really be done for them. Mice whose tails have kinks, notches or lumps should not be bred, even if their health and behavior are fine, because they may pass a gene on to their offspring that could cause spinal problems.

Wet Tail

This is not very common in mice; it is most common in hamsters, gerbils and guinea pigs. It is usually caused by urine leakage or problems using the toilet and can be treated. If left untreated for long periods of time it can be fatal. The symptoms include:

  • wetness around the genitals and lower back
  • discomfort
  • seeming confusion when using the toilet
  • messy toilet regime
  • shaking
  • loss of appetite

Wet tail can be mistaken for a one-time occurrence of wet hindquarters from the mouse sitting in a bowl of water or against the water bottle. The easiest way to prevent this kind of soggy bottom is to keep the cage clean and dry and make sure the water bottle is not faulty; leaking water bottles can be a problem. If using a bowl switch to a bottle. If you suspect wet-tail disease, as opposed to the mouse just sitting on a wet patch or water bowl, go to the vet's.

URI (Upper Respiratory Infection)

This can be fatal quite quickly to mice. It is caused by dusty sawdust (not wood shavings), dirty or damp conditions, unhygienic routine, or filthy bedding. The symptoms include:

  • laboured breathing
  • shaking
  • loss of appetite
  • watery eyes
  • fatigue
  • sitting hunched over or lying down
  • (sometimes) hair loss

Your mouse will appear very sick with a breathing problem. Get them to the vet's as soon as possible; this illness must be checked and treated properly or your mouse is likely to die. Clean out the cage thoroughly, check for any damp or problems, and keep it in good condition; URIs are most common in dusty or dirty conditions, tanks, and bin cages.


Influenza is similar to the common cold but more likely to become fatal. The symptoms are similar but the mouse will be in much worse condition:

  • runny eyes
  • sneezing
  • wheezing
  • shaking
  • fluctuating body temperature
  • tiredness
  • loss of appetite
  • dull coat

If these symptoms persist or worsen, or the mouse becomes limp and struggles to walk, then the mouse must go to the vet's or it could die. To prevent influenza, do not touch your pet if you have flu, as mice catch it from humans. If you have been out in public, wash your hands with anti-bacterial soap, as this will keep this and other problems (such as winter vomiting or norovirus) from spreading to your mouse. Have someone else care for them if you are too ill, and keep things as clean as possible. Also, clean out the cage regularly and make sure the mouse has plenty to eat and drink.

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Comments 19 comments

Julia 4 years ago

Well we are renting this house, and there are some mice time to time. The 2 baby mice ive seen are both really wet looking soaked, they feel wet not only in lower areas. And one recently seen has bulgy eyes. We feel bad but we don't know what it even is. Any ideas?

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ILoveMice 4 years ago from England. Author

Sometimes just let nature take it's course, bulging eyes are usually agitation or distress in young mice this can be common. It is difficult to treat a mouse especially a wild one they can die of shock, it's best t leave them alone.

Emma 3 years ago

I have had my mouse Harrison since March and lately he has been acting really strange in addition to a deteriorating health. I plan to take him to the vet but until I am able to get an appointment I was hoping you could give me some insight. It's only been about a week or so since I noticed a lump on the side of his neck, just in front of his shoulder. It was fairly small when I first spotted it but now I am sure it has gotten bigger.

Harrison has the same energy level as usual and is eating and drinking normally. However, he scratches abnormally hard at his ears, to the point that they are scratched up and he squeaks every time he touches them, and he makes very strange noises that I have never heard from him before. He especially makes these noises when he is grooming himself, which he is starting to do way more often than usual (but he only focuses on his nose and ears). I am really worried about Harrison and don't know what to do or expect next until I get him to a vet. What do you think?

Brylee 2 years ago

My mouse, Snickerdoodle, is not acting quite right. After his fellow mouse died, Oreo, he hasn't been looking too good. He is missing patches of fur near his shoulders, discharge from his eyes, shaky walking, lethargic behavior, his eyes have also changed color, and I think his poop has lightened. I have not taken him to the vet yet. He also looks a little bloated in the stomach area.

I really need help. Should I just put him down? What do you think? Is there even any hope for her?

plz help!! 2 years ago

i know your specialty is in regular mice, but i have a dwarf mouse named yoyo and ive had her for about 4 months, she is usually active and running all around her cage, but for 2 days she has been inactive, and really tired looking, she is squinting a lot too, it seems she has become more aggressive also. i do not have the money to take her to the vet bc my family is very poor. do u have any home remides or tips in mind?

Caitlin 22 months ago

I brought a 5 week old mouse today and she has been sneezing and peed a pinkish-red colour, what is wrong with her??

Diana 19 months ago

I have a white hopper mouse and recently her fur has been becoming blackish is that normal?

jenn. 18 months ago

Our pet mouse seems to be very inactive. He looks a bit more rounder in his belly and midsection, but you can feel his spine very prominently. He hasn't been running on his wheel as often as he used to, and he tends to sleep more than he used to. His eyes aren't as sparkling anymore; and he tends to squinch them instead of having them wide open. His breathing also seems a bit more heavy as his whole body moves every time he does. Any ideas as to what could be wrong. He's also about (I'm making an educated guess) two years of age. We used to have two mice, but the other one died of a severe brain infection. Given that they were brothers, I was wondering if perhaps it could be a genetic ailment.

Tiru 16 months ago

Hey. I am petting 2 white mice Rose (female) anf berry (male).

Berry has been fine. But rose seems to have grown something large,the size of a kidney bean under her tail. I will be taking her to a vet very soon. Could you possibly let me know what it is?

Sutty and sandy 16 months ago

Hello can any one help one of my mice has gone skinny and she has got white dots on her eyes she used to be the fatter one of the two and the other mouse we seen a cut on her left side yesterday it doesn't seem wet but on her right lower side she has a hard lump please help they are both nearly 3 years old

Julia 15 months ago

Hi i have a house mouse and i believe he is sick. He barely eats, he wont drink, hes always sleeping, and his poop is orange. Does anyone know wat type of sick ness this is?

ryen 14 months ago

My mouse is almost a year old. When we got her she was the fattest and biggest of the group of four. She has been acting really strange, she can't seem to hold up her head, she can't walk correctly and she has gotten skinnier every day. I can feel her spine and hip bones. I haven't felt for lumps but there is nothing prominently wrong with her. I just want to help her. If she is suffering and there is nothing we can do j don't want her in pain

moosey yesterday after bath,become dull,watery eyes,hard to walk & eat ,most of the time sleep. 7 months ago

I have a mouse 1.3 Year,named moosey yesterday after bath,become dull,watery eyes,hard to walk & eat ,most of the time sleep.

Sushmita 6 months ago

I have a white mouse which is just 1 month old. He used to be healthy, active and fat but from yesterday he is not eating anything and taking breath from his mouth. Now he is totally skinny. Would you please tell me what can i do for him before I take him to vet?

jonathan 6 months ago

my pet mouse is scratching him self a lot whats wrong with him

Mouseyy 5 months ago

Please help someone! I've seen a vet for my mouse, who keeps scratching very badly, and he says it's not mites. But it's gotten worse, very sore/inflamed. She has all symptoms of mites, but then also too of allergy, as there is apparently some overlap. Any advice PLEASE? So worried for her.

Her cagemates are all seemingly fine, which may suggest that it's not mites. I've heard that too much protein in the diet could be the cause, so I'm working on reducing this now. PLEASE HELP, SOMEONE!

DanTDM is bae 5 months ago

Hey my mouse is about 3 years old now and she had a sister who died about 6 months ago but she has been doing fine ever since but these past few days she hasn't eaten and is sleeping all day occasionally getting up she barley drinks and only nibbles a bit of her treat and then goes back to sleep I can also hear a sneezing noise that is constant anyone one now how to help or what this is and if it is treatable?

Elliander Eldridge 5 months ago

Hi, I was hoping you could provide insight as to a situation we went through:

One of our cats caught a wild mouse, and just played with it until we could get it away. (it was the first time in a long time) There were no punctures, no bleeding from the mouth, or any other visible signs of injury. It was in shock though with an extremely weak pulse. Gradually, in the warmth of my hand, it came to, and we gave it some bedding with some food and water that was safe and warm. That evening breathing was heavy and it had no use of it's hind legs, but moved around with it's front. The next day it was much more relaxed, and it started to eat at least pieces of raw sunflower seed and drink water. It was more relaxed with us. The next day it seemed content, it's eyes pressed together with what looked like a content look with I gently stroked it (to dry it since it got water on it) and it was starting to regain movement of it's hind legs. It was testing them, stretching them, and able to rest on them. Wasn't really using them yet though, That night I checked on it and made sure it drank water. The following morning? It was dead. It's eyes were closed, and it was in the position it would usually sleep in so it went in it's sleep. It's body was stiff and there was a slight green on it's belly fur. What happened? It seemed to be making a steady recovery, then just died. Is there anything I could have done differently? 3 months ago

my daughter got a mouse few weeks bk theres swomething wrong and not right moving very slowly shaking also looks to be 1of her eyes is popping out! whats going on plz help!!!

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