should I treat an itchy mouse with ivermectin?

Question
Hello, my mouse is a regular little mouse from Petco. Currently he is scratching his ears and face and starting to lose fur. His left ear also looks as if it has started bleeding because I can see dried blood in that ear. His main problem is his ears and face but he is also scratching his back, neck and stomach. I think it might be an external parasite because I had not been able to clean his cage in a long time (2 months + unfortunately ) and my family can't stand even a little smell so they would not clean it either. I have had him for over a year now and when I first got him he had developed a large bald bump on his back which we found out was a food allergy (block food with a lot of protein is what we think he reacted too#. We switched the food and then he was fine and the bump went away. My point being is that he is sensitive #I assume since that was only an allergy.# His cage is now clean #All clean and all items pre-frozen for 24 hours to rid the parasites# but I think the damage is already done.

I want to know where I can obtain Ivermectin #Petco doesn't have that sort of thing since it is mostly for cattle# and whether it would be better for him to ingest it or apply it topically #diluted I presume for both). Or is there any other treatment I can obtain from a nearby Petco or some type of pet store that will help him?

Note: I do not handle my mouse. From day one even when I tried letting him get used to me he would bite the gloves I was wearing. Therefore even a slight touch on the back sends him scurrying into his huts.

Answer
Dear Jenna,

Your mouse certainly has the signs of a serious parasitic infection, although to be sure, you would have to bring him to a vet.  A vet also has access to mouse-sized ivermectin.  Although you can buy ivermectin for horses or cows, I would never suggest trying to guess how much would help or how much would kill or maim the mouse.  Luckily, there is something more available, and that is a flea and tick spray for rodents from the company eight in one.  I hope you can get it from a local pet store, because it sounds like your mouse is in serious distress. But if not, here is one source:

http://www.petsmart.com/product/index.jsp?productId=2752081

In order to treat the mouse you will have to handle him.  Even though he is biting the gloves, he will be better off after he is treated.  I suggest having a helper with you.  One person will hold onto the tail of the mouse near its base and hold him on their hand, while the other treats him. Be careful of  his nose and eyes, even though he is squirming.

The following post describes how to use the spray.  Although I recommended a weaker (bird) spray for the mouse in the post, your mouse sounds like he has a more serious case and I recommend the rodent spray.

http://en.allexperts.com/q/Mice-3824/2009/1/mouse-scratching-itself-missing.htm

Best of luck to the little mouse. In the future, I recommend more frequent cage changes.  When the cage is dirty, the ammonia from their own urine can give them serious, sometimes permanent respiratory problems.

squeaks,

Natasha