We have two very healthy, very well-adjusted cats (one male, one
female) who are both ten years old, and who have been raised together
from the age of eight weeks.  The only time these cats ever see the
vet is for their yearly checkup; they've just never had any other
medical problems.  They always go to the vet together, in one
carrycase, and come home together.

During our recent annual checkup, we found that the male had an
unhealthy buildup of plaque and tartar, requiring dental work under
general anasthesia.  Our vet is very good and never recommends
unnecessary procedures, so we scheduled the dental work and took the
cat in this morning.

All went well, and we picked up the treated cat this evening after the
general anasthesia had completely worn off.  He was stumbling a bit,
so we took all the necessary precautions (closing off access to
stairs, watching if he jumped up to his usual heights that he could
also get down, etc.).  The female cat shied away from him when we
first came in, and we figured it was the usual "vet smell" reaction,
and maybe also she was frightened that he was walking strangely.  But
we were completely shocked later on in the evening when we heard a
hissing and a low growling.  The male was standing very sweetly and
placidly near the female, and she was behaving very aggressively, like
he was a strange cat!  We ended up having to watch them all through
the evening, because the male was trying to engage in normal behavior
with the female (they were raised together, and so often groom one
another, play, playfully fight, chase, etc.), but anytime he got
within sight of the female she crouched down low and her pupils
dilated and she hissed and growled low in her throat.

The female, who is _quite_ large and loves her food, is apparently so
freaked out by the male that she wouldn't even walk past him earlier
to get to a dish of tuna.

This is now hours later, and we're wondering whether we're going to be
able to sleep.  He wants to make friends; but she's likely to tear him
apart if we take our eyes off of them.

Is this normal?  Is there anything we can do to prove to the female
that this is the same male who left the house this morning?  We've
been picking him up and petting him, and he's been rubbing against us
since coming home, so he's definitely loaded up on our smell again.
I'm just anxious that we're going to wake up and find her behaving the
same way toward him tomorrow...

Thanks in advance,

Amy