I have less experience with mouse illnesses than my rats, but I can possibly offer some general knowledge based on my rat ownership and my supposing that mice aren't going to be that different in those particular areas. (I hope
First of all, I think I can set your mind at ease in that mice can't catch 'colds' from us. So you being sick won't cause your mice to be sick. There are a very select few diseases we can catch from mice and likely vice versa (diseases that can transfer between pets and people are sometimes referred to as zoonoses-lit. zoo noses- or zoonosis), but they are all /extremely/ rare in the average home. Here's a list if you're interested in doing your own research: http://www.kingcounty.gov/healthserv...ocketPets.aspx
I know rats have extremely delicate respiratory systems. Mice can suffer too. Based on my experience with rats, I can tell you bedding to avoid because they can cause respiratory flare ups.
1) Pine or Cedar wood shavings or saw dust: The phenols they carry that also makes them smell nice to us are extremely irritating to little rodent lungs. The only recommended form of wood bedding commonly available is Aspin wood shavings.
2) Any bedding that is scented. Always opt for the unscented variety.
3) Any bedding that is dusty. Carefresh is generally okay, but is a bit dusty.
Here's a link to bedding info: http://www.petinfopackets.com/rats/ratbedding.html
I don't think the changes in her diet would cause a problem. If diet is an issue, it would likely be a long term issue. IE: If she's not getting the right nutrients and over time that's compromised her immune system.
One possibility is that she is suffering from Myco.
Mycoplasma pulmonis, or myco for short, is something rats and as I have read today, mice can have. It's a bacteria that spreads quickly and easily and lives in the mucous linings of the respiratory system and genitals. It is highly difficult to remove it from a rodent colony once it's there. It's so prevalent that it's generally assumed that virtually all pet rats in the U.S. and Canada carry it chronically.
What it does is on a low grade level constantly attacks a rodent's lungs and occasionally the genital area over the course of their entire life. If the rodent's immune system is strong, they can fight it back. Once a rodent's immune system is compromised though, the bacteria reproduce rapidly and cause an inflammatory flare up. This leaves the rodent open to a secondary infection like an upper respiratory infection (URI), pneumonia, or in the genitals, a urinary tract infection (UTI). As if a life threatening pneumonia or urinary tract infection isn't enough, once the secondary infection gets in, the poor animal's immune system is further compromised, and the myco bacteria go nuts; Reproducing and attacking the animal, who is already sick. The animal eventually spirals down because of the secondary infection and dies.
Since you can't really get rid of it, dealing with it is a matter of maintenance and prevention.
*Obtain pets proven to be bred specifically for stronger immune systems.
*Feed the pet an optimal healthy diet.
*Keep an environment that is low on breathable irritants: smoke, perfumes, mold, strong cleaning supplies or other strong chemicals used in the rodent's air space, dusty bedding, dirty rodent housing, dirty home in general.
*keep the animal as stress free as possible.
*have good ventilation in the cage, but away from drafts and temperature extremes.
* Keep the home free of wild rodents.
* Practice strict quarantine practices as much as possible (see below for more info).
*Prompt and proper antibiotic treatments during flare ups.
Quarantine (QT) in a nutshell is the following:
If you as an owner come in contact with a known place that harbors wild rodents, any pet shop, or another home where they have pet rodents, stay away from your home for 4 hours following last exposure. This gives any pathogens time to die before you bring them home to your rodents.
Blow your nose and shower and change clothes before going near your rodents again.
Wash hands before and after handling your rodents which is always a sensible practice with any pet owner.
Before any new rodent is brought into the same home as your current colony, keep them in another location separately for a barest minimum of 2 weeks but preferably 5 weeks, during which time they are completely symptom free and healthy. If one is symptomatic of something, the animal stays in quarantine until they are symptom free and then once the symptoms are gone, you start the 2-5 week symptom free count down before you introduce them to the same house as your current colony.
The key is a separate air space. Some homes have central heat and air...so even if you keep the animal in a different room, the air is circulated through the entire house to expose the other rodents.
All that said, I can hypothesize that what may be going on is your one little mousy happens to have a weaker immune system than the others. Maybe, maybe not, but if so, and something like myco is present in your colony, she would be more prone to flare up. Or she may be more sensitive to the bedding, or stress, or any number of things.
If it happens to be myco, then what you could be seeing is the beginnings of a URI. This can only be treated by antibiotics from a knowledgeable vet. You'll want to do research to find a vet who is experienced in treating pocket pets. I had to call around my entire city. Out of about 50 vets, I found three practices who could treat my rats.
Prepare for sticker shock and be willing to shop around and educate yourself. I had one vet price gouge me for $60 an office visit, and $80 for antibiotics. I went to another vet who charged me $25 for an office visit and $30 for antibiotics.
Hope this helps!