Gosh, have they suggested anything?? Are they having you try anything?? WHen
this happened to us once the cat was much younger (years ago now). The vet
just gave him a bazillion antibiotics and he eventually got better but maybe
that would have happened on its own. I hope others have suggestions. Can he
go to the bathroom OK?

Did they say what they suspected was wrong with the back? What kind of
spinal problems?

W

What kind of spinal problems?  Not all spinal problems are crippling.

The first Vet

Are his hind paws cool and/or are his nail beds cyanotic (bluish)?  Was his
heart x-rayed or echoed?

Was a blood test done?  Potassium levels checked?

If a problem in his back made him lose feeling in his legs, it
might not be sore to touch or examination.

Years ago, when my mother's cat was 12, he suddenly became paralyzed
from the waist down one afternoon, from a blood clot.  My mother
rushed him immediately to the vet, but the cat unfortunately panicked
all the way there, and drowned in his saliva.

A week before my cat's recent thyroid surgery, he came in from the
garage late at night, limping with one rear foot curled upside down.
He'd been lying on the cement floor for hours, and had become a bony
old thing from the hyperthyroid, so at first, I thought maybe his
foot was "asleep."  There was nothing visually wrong with the foot,
and he wasn't in any pain when I examined it.

The next morning he was still limping with his foot curled upside
down.  It was Sunday, so (after consulting Megan to see if she had
any experience with her many cats limping in that manner) I brought
him to the emergency animal clinic, where they thought he probably
had a blood clot, or perhaps nerve damage -- that it might get worse
or get better or stay the same.  

But he had a good femoral pulse (thigh pulse) in the leg, and good
reflexes down to the ankle.  The foot was somewhat cooler than the
other 3 feet by that time.  The base of the claws were a paler pink
than the other feet, but not the sort of bluish as if he were in danger
of losing the foot from lack of circulation.  He had some feeling in
the foot, but she had to pinch his toe pretty hard before he reacted.
There was nothing much else to do, according to the emergency vet,
but wait and see if he got worse or better, and bring him back in
if he got worse.  So I brought him home to rest until he could see
my vet Monday morning.  His foot got noticably colder that night,
but the nailbeds stayed pale pink.

Monday, I brought him to my vet, who was in surgery at the time,
and the associate vet examined him, and relayed the info to my vet,
and also took the pre-op bloodwork so that he could be taken off
the Tapazole.  His foot was quite cold when we got there, but by
the time the blood test results were done about 20 minutes later,
when my vet came in, his foot was warm.  It seems he had a pinched
nerve in the hip area, and the examinations must have manipulated
something to unpinch it.

She sent him home with Medicam drops (pain relief and
anti-inflammatory)  to mix with food, and I mixed it with a
tablespoon of chicken babyfood in a saucer, so he could eat lying
down more easily.  Tues, he was walking with his foot right side up,
but he was putting the leg down too far out or too far in a lot, and
stumbling somewhat.  By Wed, he had somewhat better control of the leg,
and by Fri, only a slight limp, and after the weekend, no limp.

I feel very, very lucky that his problem was only a pinched nerve.
He's recovered beautifully from the thyroid and dental surgery.

Sending heartfelt purrs that kitty will recover.  Did Vets consider a
stroke at all?  Let us know how he is doing.  MLB