Mouse Has Sporadic Episodes Of Labored Breathing

Is a mouse’s sporadic breathing trouble due to a respiratory problem, allergies, seizures or something else?

Q: I have an 11-month-old, female mouse, and she is having unusual “episodes.” About three weeks ago, she had her first episode while she was playing with me on the couch and eating a sunflower seed as a treat. She suddenly started to make a sneezing or coughing-type sound, her breathing was audible, almost like the mucus sound when a person has a severe cold, and she stopped moving around. She was breathing with her mouth open, her side was heaving heavily and a clicking/chirping sound was pretty loud. At the time I thought she was choking on her seed, so I gave her a drop of water with a small syringe. About 30 minutes later, the episode suddenly ended and her breathing was no longer audible, not even the mucus sound or clicking sound. Her activity level went back to normal as if nothing had happened.

Next day, she had the same mysterious episode, which lasted 15 minutes or so. As with the first time, it came on suddenly with no prior sign, then it went away suddenly. When she had the same episode again on the third day, I thought of a possible respiratory infection. Due to it being the weekend, I had to wait two days to take her to veterinarian. During the weekend, she sneezed from time to time, but without the episode.

When I took her to vet on Monday, I was told that this is very unlikely to be a respiratory infection, as her symptoms come and completely disappear for the most of the day. She was prescribed Benadryl, which I was instructed to give to her only if she was having the episode. The vet suspected an allergy.

She had the episode on the same evening for an hour, so I gave her Benadryl. For the next few days, she had the same episode for a short while, 10 to 15 minutes, and she continued to sneeze a little for maybe three or four days. Then, all of the symptoms went away completely without Benadryl.

In the meantime, I followed some advice from a mouse expert and changed her food to only oatmeal to see if a food allergen caused this, because I did not think bedding was an issue. I have been using the same bedding for as long as I have had her. I use paper bedding with natural dried lavender pieces already mixed in.

She had no symptoms for a week after that. The day before yesterday, she had the same episode again, and this time it lasted five hours. I was really scared.

She is a very active mouse, however during the episode she just sits in one spot, breathing heavily with the mucus sound, clicking, chirping and her body heaving. It looks as though she is so weak and sad. But the weirdest part is, once the episode goes away, she is perfectly fine, eats well, her droppings are perfect, and she is very, very active — not making a sound while breathing. (I often put her on my ear to check her respiratory sound.)
She does, however, sneeze from time to time.

Tonight she had the same episode, and I took her out of the cage and gave her a massage, which she seems to really enjoy. A few minutes later, the episode was gone.
I am not sure what is causing the episodes, because the episodes sometimes happen in the cage, sometimes outside of the cage.

I changed her bedding today to organic natural paper towel just to see how she will do. Right now, it seems as though her sneezing is gone completely.

I am just confused. If this was a respiratory infection, wouldn’t the symptoms be pretty consistent or at least never completely go away like her symptoms do? But if it is allergy, I cannot pinpoint the cause.

The only thing I can think of is that I changed my shampoo right before her first episode three weeks ago. Could this be the problem?

She is very, very special to my husband and me. She is loving and unbelievably tame. I just want to make sure she is OK.

A: Diseases in mice can be very difficult to diagnose. The main reason is the size of mice. We can safely take only a couple of drops of blood from mice, and that is not enough to look for all of the different diseases we need to hunt for.

Disorders and diseases of mice have been well-documented over the years due to their use in research. We know as much about mice as we do almost any animal. And many of the conditions that affect mice used in the laboratory affect our pet mice. But even with all of that knowledge, we still are sometimes at a loss to explain signs of diseases.

In this case, your veterinarian is trying to help with a problem using a medication that is very safe. If this was an allergy, then the medication should have helped your mouse. And in case the medication was not helpful, you did the next best thing — you removed from her environment any items that could be an allergen, and she still had these episodes.

You also state very astutely that if this was a respiratory infection, it should not go away so easily without treatment.

What you are describing sounds exactly like seizures. Seizures can look as you describe — start suddenly, end suddenly and just after it ends the patient looks like nothing happened. Seizures can take all forms, and even though you may think this is a respiratory “attack,” what you describe in your mouse could also be a description of a seizure.

If these are seizures, there are many causes for seizures. These include trauma, infection, cancer and a big category called epilepsy. Even with larger animals, it can be difficult to pinpoint the reason for seizures. We do extensive blood tests and cultures, we do MRIs and CT imaging, we examine the cerebral spinal fluid, and we do biopsies.

Unfortunately, almost all of those methods are not available to use on mice due to their size.

Here is what I suggest you do. Keep a record of when an episode starts, the length of the episode and what the episode looks like. Take a video of the episode so you can show that to your veterinarian. All of this might help your vet decide the next step to take with treatment of your mouse. In the meantime, when an episode occurs, make sure your mouse cannot harm herself and comes out of the episode in a safe area of the cage.

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Critters · Mice and Rats