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Dear Tamarah,

A couple months ago my friend and I bought two female mice on a whim.  My friend and I agreed that if we were going to purchase pets we were going to do it properly, so even though we became mouse owners unexpectedly we purchased everything necessary to make them a proper home.

After three weeks, one of the mice became sick and died almost within a day.  We did everything we could to take care of her (I stayed up with her most of the night, put a hot water bottle under the cage, etc.), but we couldn't save her.  We determined via research that she was suffering from a upper respiratory infection.  I asked at the pet shop where we'd purchased the mice if we could prevent the other from becoming sick, and they said that URI's are not contagious and our other mouse was fine.

The other mouse was so despondent after we lost the first that we bought another mouse for company.  They were introduced and got along very well until the older mouse became sick.  We took this mouse to the pet store (where we had been promised free medical care) and were told that our mouse was "pretty all right for a mouse," and then, once she got worse, we took her to an actual veterinarian.  The vet gave us medication, but the little mouse died on the way home.  Thankfully we noticed and were able to hold her.

The last mouse, who is now very friendly (she was terrified when we brought her home, and so bossy when the older mouse became sick that we had to separate them), is just fine so far.  However, I know now that URI's are inbred in pet store mice.  I have tetracycline which I believe prolonged the life of the second mouse, and medicine for a URI if this mouse begins showing symptoms.  What can we do to keep her healthy?  We bought them on a whim but we bought them seriously, and want to keep her from this sickness.  Thank you.

Hi Sara,

The information the pet shop gave you about respiratory infections not being contagious is so extremely far from the truth.  URIs have been known to wipe out whole breeding colonies due to being easily spread and symptoms progressing rapidly, even though it can take up to 3 weeks to show. It's upsetting to me that the shop gave you such bad information, but thank goodness you have a vet available who can help if needed.

Tetracycline is an excellent general antibiotic. By general, I mean it's active against many kinds of infections, but it's not the most targeted or effective if the particular infection causing a URI is resistant.  Therefore, unless you can give your vet a call for better advice, tetracycline can be a good idea to give now, *before* symptoms show, since she did have exposure.  Give the full course unless your vet tells you otherwise, even if she doesn't develop any symptoms.  I would personally consider her infection-free if she goes one month past the end of the antibiotics with no symptoms.  Then you can relax!  And of course if she does start coughing, clicking, sneezing, or showing more serious signs like a rough coat or hunching, you have your vet-prescribed medication ready and on hand.

If she was pretty bossy with the other female, she may not want a roommate in the future. However, if you do decide to try getting her a friend, the best way to keep her safe is to isolate any new mice in their own cage in a separate room for one month. One month symptom free means they aren't bringing home any diseases, which can present themselves after the stress of a move. It also gives you a chance to let her settle in and get to know her and play one on one with her before introducing them. This kind of initial isolation is very common among mouse breeders for the purpose of keeping everyone healthy, and it's a wise practice.

I'm so sorry for your loss and the poor experience you had. My best wishes for the health of your current mouse, and let me know if there's anything else I can do to help!



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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

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