I have an 84 pound, eight year old Old English Sheepdog.  His left rear leg was amputated due to cancer.  His recovery was uneventful; rounds of chemotherapy were successful and he was back to his old self within weeks.  He was running and jumping like a puppy.  Then he injured his right back leg.  He was seen by his vet, ER doctor, oncologist, radiologist, and orthopedist.  Multiple tests were run and it was determined he sprained his knee and injured his groin muscle.  We have ended week three and there is no improvement.  He is on multiple pain meds but remains completely lame.  Has anyone had similar occurrence, and if so, did you pet show any improvement and when?  I will fight with him as long as he wants to fight, but I'm worried he's giving up.  His days and nights are spent sleeping and crying for those few hours when his pain med has worn off but it's not time for the next dose.  Any help would be so appreciated.