My daughter's holland lop seems to be going. I don't know what the actual problem is, but he is now unable to use his back legs and is very lethargic. Yesterday he stopped drinking water and barely ate. Still no water today, even when I put the nipple in his mouth. He's reached typical end of life span age, 8 years. I hate to see it suffer, any idea how long he will last now that he isn't drinking? Is there anything I can do to ease his passing?