odd mouse behavior

Question
Hi Cass! I am really thankful to have come across this website. I bought two feeder mice in March to keep as pets (Itty-Bitty & Amelia), and I ADORE them. Let me give you a bit of a background: Itty-Bitty has always appeared to be healthy. I noticed shortly after buying them that Amelia breathed differently than Itty-Bitty (she sort of jerks when she breathes, and she coughs/sneezes every now and then), and it has been like that for months. (I think that may or may not have to do with the fact that the petstore kept the mice on cedar or pine bedding.)

When I first got them, Amelia was always on the go. She scaled the wall of the bag I brought her home in, and she never stopped running on her wheel, day or night! We said it was like she was living her life in fast-forward. Within the past couple months, she has slowed down a lot. She doesn't run nearly as fast, and in fact, she hardly ever runs at all. In the past couple weeks, I have noticed that she will tend to climb up on the wheel and just sit there for minutes, breathing with her paws up. She'll jog a couple steps and then sit again. She "zones out" like this all over her aquarium - it is as if she suddenly forgot what she was doing. She is doing it right now. What I am writing for, is to see if this might be a symptom of old age in mice. She hasnt lost any of her fur as far as I can tell. I am fairly certain that because Itty-Bitty was so small when I bought her that she is relatively young. Amelia I am not so sure about. If it is not necessarily a symptom of old age, what can I do? Should I worry? Are there vitamins or anything else that I can get for them?

Also in the past couple weeks, she is spending less time outside of their "hut." Itty-Bitty and Amelia used to snuggle together all the time, and they still do to an extent, but sometimes Amelia will lay down outside the hut. Should I be concerned about that?

Thank you so much for your time!! I really appreciate any help and advice you could provide.

-Rachael

Answer
Unfortunately most rats and mice carry a bacteria called Mycoplasmosis, which can cause upper respiratory infections. Your best bet would be to get her over to a small animal veterinarian as soon as you can in case she does have this illness. It can be treated, but not cured, with antibiotics such as Baytril or Doxycycline. She is nearing old age, as far as mice are concerned, and it would be expected for her to slow down her activity a bit. Just make sure that they both have clean cages and water, and a high quality good to eat. Keep them both away from drafts, and if you plan on using a heater in the winter make sure they don't get too hot. Have you tried finding a new hidey area for her? Are there any outside stress causes such as little kids or cats?