Hi Ann,
I am sorry your kitty isn't feeling well. There is no way to predict exactly how long a cat with Lymphoma will live. Many factors contribute to this, including how healthy the kitty was before diagnosis, age, underlying conditions and stage of the lymphoma. It will be pretty impossible to nail it down to an exact science, but your vet may be able to give you some guidelines based on his medical history. I think that less invasive methods should be used to try and get a diagnosis before you allow your kitty to undergo a surgical procedure. Ask your vet about radiographs and ultrasound. Both can be very useful tools to take a look at the organs and structures inside your kitty. A skilled ultrasonographer can determine if intestinal lymph nodes are enlarged, and can identify subtle tumors that a novice might miss. See the following website for more information on lymphoma.
http://www.veterinarypartner.com/Content.plx?P=A&S=O&C=O&A=1446
Inflammatory Bowel Disease is a group of gastrointestinal diseases that can involve the stomach, large intestine and small intestine or a combination thereof. The symptoms include intermittent vomiting, diarrhea, poor hair coat, weight loss, lethargy, heart murmur, thickened bowel loops and enlarged mesenteric lymph nodes. Treatment is very involved and consists of corticosteroids (prednisone or budesonide), antibiotics (metronidazole, tylosin), anti-diarrheal agents (loperamide), special diets, immunosuppressive medicines (azathioprene) and sometimes chemotherapeutic agents (chlorambucil). See the following website for more information on IBD.
http://www.veterinarypartner.com/Content.plx?P=A&S=O&C=O&A=598
I am worried that he is turning down food. He has got to eat something, it doesn't matter whether it is tunafish, or boiled chicken, just get him to eat. If he will not eat on his own you will have to start syringe feeding him. Your vet should carry some suitable rescue diets (a/d) that will be easy to syringe. Meat baby foods are also a good choice, check with your vet for your cats daily quantity. If your kitty does not eat enough, his liver will start to shut down. He will develop a condition called fatty liver disease, which I do not feel he will survive (given his existing condition). See the following website for more information on Fatty liver disease.
http://www.veterinarypartner.com/Content.plx?P=A&S=O&C=O&A=1455
I understand and agree with your reluctance to put kitty under anesthesia. I feel that his remaining time (and it could be a long time :)) should be as happy and pain free as possible. I know that bloodwork has already been run, but a urinalysis and Early renal disease test could pick up some kidney disease before it is apparent on bloodwork (75% of kidney function is lost before changes are obvious on bloodwork, approximately 35% of kidney function is lost before changes are obvious on urinalysis and as little as 25% of kidney function is lost before changes occur on an E.R.D. test). I am mentioning this because kidney cats are usually nauseated, and that is often sufficient to put them off their food. Anti-nausea medicines are useful to make your kitty more comfortable. Sometimes pepcid is sufficient and sometimes a prescription medication like metoclopramide is needed. See your vet for doses on pepcid.
I know that you are worried about this kitty, and I hope that he starts to feel better and eat. Please let me know if I can be of further assistance. If this has been helpful, please hit the green accept button. Best of luck with your kitty.
Emergency Critical Care Nurse
16+ years of veterinary experience