Bleeding from the ear?

Question
QUESTION: Hi
I've had mice for the past 9 months or so. We had an original 3 then decided to get some more. We only ended up keeping one of them. About 3 months ago, one of my mice got all strange. She started getting skinny and I think she went blind and deaf. That was okay because she was still happy and energetic, but within a space of 48 hours she stopped eating, she was 'spazzing out' and was walking funny.  Before we knew it, she had died. I was devistated!
After her, we thought we would get 3 new mice for extra company, two girls and a boy. One of the original mice took over the roll of leader, and she changed. It seemed that the other mice exiled her. She was becoming really anti social. And there were fights all the time. We figured that two of the new mice we doing this, so during most of the day we were separating them.
Last night, the one that is all by her self, I found her to have blood near her right ear and it is tender. I have no idea where this has come from? Do you think it's mites and that's what killed our last mouse, or is this from fighting? Any ideas would be a help? I'm so worried.

ANSWER: Hi Kat,

Female mice maintain a social structure, and additions (such as separating them sometimes and then putting them back together) can really disrupt this hierarchy.  For normal females, there is always a little chasing and ruckus for the first several hours of being together, but not usually more than a day or two.  Some females, however, become either too stressed to remain in the colony, or would just plain prefer to be alone.  It's not fair to these females to make them stay in unpleasant situations, so separating them for good may be a good idea.  It's also important to keep males separate from females except for two weeks at a time while breeding.  A male's presence and sexual advances are extremely stressful for females, and can seem to change their personalities.  I had one female once who, when I attempted to breed her with a buck, became terrified of any contact or of other mice.  It's important in this situation to consider the mental well-being of the females, as this almost always winds up affecting their physical health.

As far as what killed the first mouse you lost, there are several possibilities and it is very difficult for me to guess.  Mice, like most prey animals, behave as though nothing is wrong until discomfort becomes too severe for them to ignore, and then they appear to be very sick quite suddenly.  It sounds like a disease to me, rather than a parasite like mites, but whether the disease might be respiratory, infection (like from a bite or scratch), or something else entirely is almost impossible to guess without knowing a lot more about her conditions at the time.

The antisocial mouse's ear could be from an injury if she was exposed to mice she was fighting with (which is very likely, in that case), mites if accompanied by hair loss, redness, scabbing, and irritation in the area (this can be made worse by stress), or a self-destructive habit which could also result from stress or from genetics.  The first thing I'd try is to separate her 100% of the time from the other mice and to try placing her in a different room entirely.  Make sure her new environment is free from drafts and annoying sounds (like televisions, desk top computers, etc.), and apply a small amount of triple antibiotic ointment (like Neosporin) to the hurt ear.  Don't use very much, since most of it will get licked off anyways, and apply it with a clean finger or cotton swab.  This can be repeated 2-3 times a day.  If over the next few days it seems to get worse, instead of better, you can try a mite spray (excellent directions here:  http://en.allexperts.com/q/Mice-3824/2009/2/Mouse-mites.htm ).  This takes two separate applications and requires you clean the entire cage and everything in it very thoroughly to kill any mite eggs, along with freezing new bedding for at least 24 hours before use (and then thawing it, of course) to kill any possible incoming mites.  If the skin becomes very raw and scabby, it would be an excellent idea to provide a course of antibiotics to fight off infection.  Tetracycline is a great, common, general antibiotic you can provide in the water, and Natasha has terrific instructions on how to give it here:  http://en.allexperts.com/q/Mice-3824/2010/2/Tetracycline-directions-sneezing-mou  You can find tetracycline at your local pet shop, fish supply store, or feed store.

Best of luck, and let me know if you have any more questions!
-Tam

---------- FOLLOW-UP ----------

QUESTION: Thank you. That does make sense! We have separated her. We came home the other night to find she has chewen off the end of her tail and it was only hanging on by a bit of skin. It was going black so we thought best to cut it off. I'm not sure if that was the correct thing to do, but she let me clean it with a cotton bud and warm water.
She seems to be doing much better. No more blood, thank god!
There has been no scanning or redness that we have been able to see, around either ear. So that's a good sign. We get her out once a day and play with her and she snuggled right into my side :)
Thank you for your advice and if anything else arises, I'll let you know. I don't think we will put her back with the others either.

Kat :)

Answer
Sounds great!  I'm glad to hear she seems to be healing up, and enjoys cuddle time!  :)

There is a major vein that runs through the tail, so antibiotics might be a good idea, just to make sure nothing enters the body through the injury.  The link for tetracycline in my last post applies just as much to keeping infections out as for respiratory infections (the problem that questioner was having), so I'd definitely give it a shot.  It's easy to give, though, and it's always better to be on the safe side!  :)

Hope she doesn't have any other problems - she sounds like a sweetheart when she's on her own!  Best of luck,

-Tam