Agression after other cat's vet visit

So it took a few months, but our 2 year old and 6 month old females are now best buddies (yay!!). Today we took the kitten to the vet to get spayed. She was gone for about 10 hours, and of course came home with all sorts of strange smells. We were expecting some hissing initially from the cat who stayed home, but so far it's been worse than we thought - they met face to face for two seconds when the home cat screamed and lunged at the kitten (she never did that even during the first intros). We were hoping if the home cat could get a good smell of the kitten's rear end we might be in business, but no dice. Now we're trying to re-scent the kitten all over again.

My question is, for anyone who has had this problem, is it a few hours? Days? Weeks? We're in a situation now where it's very tough to keep them separated, but we don't want them to get into any nasty fights, especially while the kitten is healing from surgery.

We've had it happen for couple hours but I can't say that it is typical, hopefully, it is.

Put a dab of vanilla extract under their chins, so that is all they will smell.
Even if its in a small bathroom, until they can get along, I would keep the kitten there, so she can recover.

I had a very similar problem to the original post. I have two females from the same litter. They are 2 1/2 years old and have never been apart, so they get along just fine. One cat got a urinary tract infection. Took her to the vet and as soon as we got home the other cat starting hissing and growling at her. It's been 4 days now and it's still going on. They can't be in the same room together.

I got on this site to find out what to do. Tried the vanilla extract under the chin and within 10 minutes they were less than a foot apart and completely fine with it.

THANK YOU!!

I also have this problem with my two girls. I just got into the habit of taking them both to the vet even if only one had an appt. The vet is very understanding and will take them both and hold them so they both smell the same afterwards. If I don't do this, the aggression will usually last for a few days to a week.

When my Maggie came home from being spayed it was a couple days before the boys "remembered" who she was. I always have some mild agression when one or more cats go to the vet. The spaying made it worse because as someone on here pointed out you take away their friend & bring back a cat that smells totally differnt. Not only is there the vet smell, but spaying changes the cats smell. I am sure they will adjust again, but it may take a little bit.

yeah i had same problem with my to each time they go to the vets, the whole works the growling hissing arched backs and jumping sideways whilst having the arched back only lasted half an hour or so for us though