Cameron,

Ignore the previous poster - it's a troll.

Only you can make the call - and it's a tough one.  You'll know when the
time is right.  How long can you continue to give supportive therapy?  It
can be tough on you, especially if no improvement is seen.  What is the
quality of life your cat has?

I had a cat with reocurring URI's.  At one point it was so bad his head was
so stuffy, he couldn't smell.  Since he had no sense of smell he didn't want
to eat.  I had to tube feed him (he had also had exploratory surgery, and
got the URI from being in vets) for a week and half.  From then on he would
continue to get URI's.  Have you tried putting the cat in a small room w/a
vaporizer (like the ones they use for kids)?  It helped Z on many
occassions.  You can get one at any pharmacy for as little as $10 - if it
doesn't produce enough steam, try adding some table salt to the water, it
works.  You can use the menthol stuff and add it to the "well" too (the
vaporizer may come w/a sample).

Maybe this will help the cats sinuses clear up enough to become interested
in eating on her own.  Try it a few times a day - it won't hurt anything.

I'm sorry I can't help you more.  You can always go to another vet for
second opinion.  And I'm sorry, but you are the only one who can determine
if it's time.  I'm sure you will do whatever is best for your cat - only you
can truly judge quality of life.  Not an outsider.

Good luck and please keep us posted.  I hope she does improve.

JoJo