Inflamatory Bowel Desease

Question
I have a cat, Hercules who is 11 years old.  He's always been a skinny cat but he recently lost a lot of weight over about a 6 week span to where he looks like a skeleton with skin draped over it. I took him to the vet for a checkup.  She ran multiple tests to rule out deaseases that he may have and he was diagnosed with inflamatory bowel desease.  She gave him a steriod pill a day but he didn't show any improvement in his weight. He's still eating and drinking regularly. I called her back and she told me he could live like that another year or I could have more tests run on him which would stress him out or I could put him to sleep knowing he had a good life. In the last few weeks he has gotten to where he won't bathe and he is very dirty.  He won't use the litter box and goes on the floor.  His eyes and nose are runny.  He doesn't seem to be in any pain and still purrs alot. My husband and I are thinking about putting him to sleep but when I think about it I don't know if I'm doing the right thing.  I don't want him to suffer but I don't want to prolong life if he's really hurting.
Any advice will be appreciated.

Answer
He could also have intestinal lymphoma (cancer).  Usually with inflammatory bowel disease, I will put them on prednisone daily as well as metronidazole and change their diet to a hypoallergenic diet such as IVD Venison and Pea or one of the hydrolyzed diets such as Hill's Z/D or Royal Canin HP....diet is VERY important in these cases.  All three of these things need to be continued long term.  Some times I will give a depo-medrol injection in place of the prednisone daily pills if they are difficult to pill.   And it can take a while for them to gain back weight...he didn't get sick overnite.

Cats are very good at hiding their pain.  He may not be using the litter boxes because he is uncomfortable and associating the old boxes with pain.  I would suggest getting 2 NEW litter boxes as well as Cat Attract litter.