I understand how you feel. You've obviously loved this guy and cared very well for him for all these years and this diagnosis is difficult to hear. With FIV and at this age, I have to agree with your vet. Operating won't cure him, but will certainly put him through stress, fear and pain, along with the complications that may occur with the surgery itself.

There are various stages of FIV and since he's not in pain and still finding more pleasure in life than pain - his quality of living is considered high.

FIV (Feline Immunodeficiency Virus) is much like FeLV (Feline Leukemia Virus) and is frequently compared to human AIDS. It's important to know that FIV and/or FeLV cannot be caught by people and will not cause AIDS or HIV in humans. Studies have shown that mostly male cats are prone to FIV.

In very young or very old cats, infection is often detected when lymph nodes enlarge, the cat develops fever and blood work indicates a low white blood count. This can last for days or even months.

Other cats may be positive for FIV antibodies and show no symptoms or complications. Some have been known to live entire lifetimes without any troublesome complications or symptoms.

Some cats have a terrible time with the disease and seem to have constant complications, including inflammatory eye problems, mouth/gum inflammation, bacteria, virus, fungus and every other opportunistic illness that can take advantage of a compromised immune system. When a cat is suffering from ongoing complications like this, it's considered "stage 3".

Stage 4 animals are in the ‘terminal' stage with wasting away, other cancers and probably neurologic complications. At this point, quality of life is generally nonexistent.

When there is little or no quality of life on a daily basis, it's time to love your companion enough to let him go. Your vet will be invaluable to you in providing advice at this time.

Until then, keep lines of communication open with your vet and trust them to make the right decisions with you.

I know it feels like you're waiting for your companion to pass on, and in a way you are. But you are anyway - whether he is sick or well - we all leave these bodies. You just happen to know the reason this gentle creature will have for his going. You have time to prepare yourself (though we are never really prepared) and you have time to indulge him and love him even more than ever!

If you're wondering about whether or not you've done all you can, yes, you have. There is really not much that can be done with this disease.

He may have many years left

This UC Davis link will certainly be helpful in understanding more about it

http://www.dcn.davis.ca.us/vme/DrSue/letter.html

and http://www.winnfelinehealth.org/health/FIV.html as well as

http://www.2ndchance.info/fiv.htm (discusses possible treatments)

Good luck with him and God bless