Male rat has suddenly lost the use of his hind legs

Question
Hi,

I have two seventeen-month old male rats.  Tonight when I went to give them their dinner I noticed that one wasn't coming out of the nest for his food so opened up the nest box and found him curled up in there.  I got him to move but he couldn't use his hind legs properly at all especially his right one.  His breathing seems to be very shallow and fast and he doesn't seem able to lift his head properly.  I lowered the water bottle and food dish to see if he would attempt to drink or eat if it was easier for him to get to but he hasn't touched anything and has just dragged himself off to the corner of the cage.  I will of course be phoning the vet as soon as they are open in the morning but I was wondering if you had any advice on how I should keep him comfortable in the meantime and what you think his chances are.

Answer
It sounds like a stroke.  I am sorry this took so long to answer.  Normally I answer the same day unless I am swamped and some emails end up in spam.  

If he is on steroids, this can make him more comfortable.  How are things now? I am hoping for the best here....