Check the paw and pads.

Yes! I flipped out because my little tabby was limping and wincing when
she put weight on one of her back legs. (She had a new cat shelf and I
*knew* she must have slipped getting up there because she was not
yet used to it.) Took her to Emergency Care, where she refused to limp.
Later that night she was clearly in pain, so the next day I took her to my
vet, where she refused to limp AND jumped from the floor to the table
and back again with no sign of pain. An hour after we got home, she was
wincing and cringing again. I actually took her back to the after hours
place where she again refused to limp! This time I made them give me
kitty narcotics in case she showed symptoms of pain--more for me
than for her, as I was clearly having more trouble with her being in
pain than SHE was. The next day she was fine and never showed
a problem with that leg again.

Point: if you can STAND to, you might wait a day and see what
happens. But of course  that limp might be a symptom of something
serious. *sigh* That is always the risk you take when you wait. I will
always err on the side of superfluous vet care rather than scanty vet
care, but that's just me.

I would take the cat to a vet for examination.  Cats are well known to hide
pain, so this is probably a sign of significant discomfort.  Earlier this
year, I had a similar situation with Holly.  She was fine one night and was
limping the next morning.  I checked carefully and couldn't see anything,
but I took her to the vet that afternoon.  He found a small cut on on pad,
but it didn't appear to be serious.  He said it was the type of cut that
might have come from some small object such as a carpet tack that might work
its way up through the carpet.  Holly is a solid black cat, and her pads are
also black, so it was very difficult (even for the vet) to see anything, but
the cut was small and didn't appear to be serious.  He prescribed some
antibiotics.

The next morning, she was limping *very* badly, and it was obvious that she
was in severe pain.  So, we went back to the vet.  The pad had become
noticeably swollen overnight.  This time, the vet used gas anesthetic so he
could probe the wound more thoroughly.  It's a good thing he did.  He told
me later that pus flew from the wound as soon as he made an incision, and he
discovered that there was an absess underneath.  This means that poor Holly
had the cut for some time but had hidden the discomfort.  It also could have
turned into something much more serious if it had not been taken care of.

So, my advice is to err on the side of caution and take your cat to the vet.

MaryL

Photos of Duffy and Holly:      >'o'<
Duffy:  http://tinyurl.com/cslwf
Holly:  http://tinyurl.com/9t68o
Duffy and Holly together:  http://tinyurl.com/8b47e

Which leg, Sue, right or left?  There's a reason for asking.

Phil

The odds are the injury won't heal in a couple of days. Even if you don't see
him limp any more. A cat is a preditor and as a preditor knows that being injured
makes him a target for other preditors. As a result every instinct he has makes
him want to hide the injury. For him to be hurt to the point were he can't hide
it any more means that he is very hurt.

As a side note he may have just gotten a "booboo" (my term). I have a year old
cat that managed to hurt his rear hip last summer. He couldn't run or jump and
barely was able to walk. Since he was due at the vet within a week of me first
noticing it and nothing seemed broked or cut I waited until his next visit. (He
was a young kitten and needed his shots.) By the time I got him to the vet he
was doing a lot better but even the vet saw him limping but could find nothing
wrong. He mentioned the concept of a "booboo" and we agreed that since it was
getting better we would let him go for another week to see how it improved.
Within the week he was fine and running like a maniac kitten.

Of course he was a kitten and not a 16 year old cat. I would get the cat to a
vet as soon as possible.