My cat has gone nuts!

Question
I have a Himalayan Persian mix, named Kaliber, he is about 2 years old and neutered when he was 6 months. He is the son of my older Himalayan Persian male named Guinness and he's 5 years old and neutered also. I have no other cats and these two have been together sense Kaliber was 5 weeks. They are both inside cats and never go out side. They normally LOVE each other, they sleep together, eat together, clean each other, they are just great loving cats! 2 days ago I had company and they left the door open and Guenness went for a stroll. I was unable to find him that night so he ended up staying out. He came home the next morning and seemed really tired but fine. However, now Kaliber has freaked out. He is constantly growling and hissing! He won't go near Guinness! Guinness does not even fight back, he just walks away. Now Kaliber has turned on me, my husband and kids. Nobody can go near him! He growls, hisses, bites and claws! We were able to catch him and isolate him in a kennel, but I don't know what to do now... He is current on all his shots and NEVER showed any signs of this kind of behavioral issues. Do you have ANY idea what caused this? Please tell me this is just temporary and will go away! I don't want him to be an outside cat and I can't keep in in a kennel forever!

Tons of concern,
Mandy

Answer
Mandy,

It sounds as if Kaliber did not recognize Guinness because he did not smell right.  Cats recognize each other by scent. If a cat encounters a strange cat, they get into that fight/fright/flight mode and cease to recognize anybody.  Usually, after a couple of days this subsides and everything returns to normal.

So I would give it a few more days and see what happens.  Mean while, do not approach Kaliber.  Let him come out of this on his own.  Let him decide when he feels he can approach you and Guinness, do not force the issue.

Let me know how he does.

If he seeems not be be shaking this problem, the vet may be able to give you something to calm him down (if you can get him into a crate).

Please let me know how it goes.

Best regards... Norm.