How to take care of an orphaned baby mouse

Question
Hi.  My nephew found 3 baby mice on his driveway.  One was alive and the other two were dead.  I brought the one living one home to try to foster it.  I have no idea how old he is.  He has fur but his eyes are closed and his ears are still back instead of sticking up.  I have done a lot of reading online about how to care for him.  I just want a little more information.  Right now, he is in a plastic shoe box with holes punched in the lid for air.  I keep half of the box on a heating pad (kept on low) and the other half off the heating pad.  The box is lined with an old tee shirt and he has a small stuffed toy in the box for comfort.  I have been feeding him soy baby formula mixed 2 parts water to one part formula.  I read on the internet that that was better than KMR or Esbilac.  We have had him for three days.  I have been feeding him ever 3 hours.  I am using a syringe with an IV catheter on the end.  There is no needle, just the tubing.  I have been weighing him on a mail scale.  He has been 4 grams the whole time we have had him.  He is not gaining.  I just sent my husband to the store to get some KMR.  I thought I would try that since the soy isn't really working.  Is there anything else I can feed him?  Do I need to be doing anything else?  Oh yeah, when everytime I feed him I massage him from the head down and then turn him over and rub his tummy and his area until he goes to the bathroom.  I just want to do the best by this little guy.  Please let me know what else I can do.  Thanks so much.

Answer
I'm going to give you some more links to web sites that might help but to me it sounds like you're dong everything you can. You're feeding him, keeping him warm, giving him comfort, and making sure he goes potty. You're doing a much better job than I did my first time. It's very hard to raise orphan babies as well as time consuming. By researching what to do you've given the little guy the best care he can get. If you've been able to keep him alive for three days that is very good and hopefully he'll survive until his eyes are open. You can start to relax more about keeping the baby warm once he's gotten fur and once his eyes are open you will have successfully raised an orphan baby mouse. The biggest thing you need to watch for is dehydration. When you pinch the baby's skin and it stays up it means the baby is dehydrated and you need to start giving him Pedialyte. Dehydration is caused by too much heat, which shouldn't be a problem as you have the cage half on and half off a heating pad. Another problem is diarrhea which can be caused by over-feeding. I'm not sure the exact ratio of feeding but I'm pretty sure it's .5cc's of food per gram of mouse. Here are the web sites, the first link is day by day pictures of baby mice so that you can ascertain the baby's age. The second and third links are just more detailed web pages on caring for orphaned baby mice. One is for orphaned rat babies but they're similar to mice so it should work as well.

http://www.thefunmouse.com/info/daybydaybabies.cfm

http://www.ratfanclub.org/orphans.html

http://www.thefunmouse.com/info/orphanedmice.cfm

Hope that was helpful, and good luck with the little mousie :)