prolonged illness in cat

Question
George my 12y/old colorpoint male cat is vomiting nearly everyday, has intermittent diarrhoea, and is losing weight (4.5kg down to 3.1kg) The vet cannot give me a diagnosis except to say he is not diabetic, Feline luke neg, and hypothyroid readings are normal. The vomiting has steadily increased from occasionally to every day or so. It is fluid and no food and little hair and about the size of a dinner plate and occurs about 5.am, he is fed tinned food morning and night and has a ravenous appetite, resorting to pinching food off the dinner table - totally out of character for this cat.Diarrhoea is quite smelly but not pale. please do you have any ideas as my vet doesn't seem to know what to try next except surgery and  George doesn't handle anaesthetic well. thanks Tania

Answer
Hi Tania!  I'm sorry it took so long for my response to reach you!  I actually answered this post twice before, but it keeps showing up in my "unanswered questions".  I believe that the website may be acting up...if not, and you've received this twice before, please accept my apology!
I can definitely understand your concern about your cat.  George is definitely displaying symptoms of IBD..Irritable Bowel Disease.  IBD causes the intestinal and stomach walls to thicken and swell.  Because the walls are thickened, nutrients is not absorbed very well, hence the weight loss you have been witnessing.  This also explains ravenous hunger.  The inflamation in the intestinal tract causes it to be very difficult for proper digestion to occur, leading to vomting and diarrhea.  The diarrhea may even have spots of blood in it due to irritation and will be very foul smelling.  IBD can be somewhat difficult to diagnose.  I almost had lost my one cat to this because no one could figure out what was going on.  It eventually had gotten so bad, that he no longer wanted to eat and because of that, he began to go into liver failure.  Finally, he was diagnosed with IBD and was started on a monthly to bi-monthly steroid injection called Depo Medrol.  This decreases the inflamation in the intestinal tract, which promotes proper digestion. This medication saved my cat's life and years later, he is still getting his injections, now every three months, and is very healthy and happy.  I would definitely mention this to your veterinarian because George is displaying the exact symptoms my Niko did.  If this is, in fact, what is ailing George, I hope the Depo Medrol helps him as much as it did my cat.
Another possibility is an intestinal parasite.  Has your veterinarian performed a fecal testing on George?  Intestinal parasites can even be contracted by indoor cats, so having a fecal testing done may be beneficial.
I wish I could be of more help.  Please let me know how George does and give him plenty of kisses for me!
Hilary