How long should I force/assist feed my cat?

[tiggy2]

Ok this is a long one so but I'll try and cut it down some.

It is my 12 year old male Tigger who will not eat enough to maintain his weight and I have been assist feeding him since July/19. He used to be a heathy 9.8 to 10 pound cat, he now hovers around 8.2-8.6 pounds, all skin and bones.
First off he always was a fussy eater and always took extra effort to keep his weight up. He also had major surgery for a blockage in hi stomach in 2011 and almost died from that...but he came back)

So this tale started on July 17 when he came into the house and went to his bed and stayed there. I picked him up and he had nothing, like a rag doll..needless to say off to the vet we went. Dr. said your cat is in a dangerous dehydration and needs immediate care, IV Fluids and of course some blood work and X-rays to see what the problem is. To make a long story short everything came back with in normal range.

Found a bump on his back and had it biopsied and it came back negative for any cancer. The last test was an ultra sound, which came back with thickening of the stomach and bowel lining and some abnormalities in that area. Basically did not know what problem was but hinted maybe cancer or IBD. He can't definitely say cancer without a biopsy of that area which would mean major surgery again. I'm already over $3,000 dollars trying to find out what the issue is and there is no guarantee what they will find or if Tigger could tolerate the surgery. So he sent me home with prednisone and I add in Pepid AC incase of upset tummy and in the feeding I add slipery elm also to help with tummy issues.

So my dilemma is should I continue force feeding him? If so for how long? What are the signs that it would be some kind of cancer?

Aside from him not eating and being skin and bones he relatively normal, the only behavior that is cropping up is he's afraid of anything that is not the same as it was yesterday or they last time he went by that area. For instance my rubber boots are usually by the back door, but I brought a small bucket in and have it by my boots, well you'd say it was some evil critter according to his behavior. Maybe eye site is going? Or he has high anxiety? I've requested something to help with his fear/anxiety. He loves being outside casing things and running up trees, he may not run as fast or climb as high, but he still has interest.

I am very frustrated with it all, as it is so very time consuming having to force feed him every day, several times a day and sometimes I can't find him as he's hiding somewhere. He will eat maybe an ounce to two ounces on his own, with me casing him around with food, so I have to force the rest into him and usually most gets done at night.

Anyway a long story, but I don't know the ending, so any advice or suggestions are welcomed. If you need more technical info. I have all the test results.

Thanks again guys..oh and he's spraying up the house, my hubby is going to kill him since spraying his clothes my guess is anxiety and a need to feel secure in familiar territory.