Why is my cat hissing and growling at his sister after just 30 minutes of separation

Question

I took my cat to the vet for 30 minutes. When I got her back home, her brother started to hiss on her and he looks aggressive. she tried to touch his nose but he still doesn't like it.

• Should I leave them alone? Can they resolve the problem?
• What is causing that problem? do you have an idea? Is it maybe the perfume of the vet? or he doesn't recognise that smell?

Answer 1

Why does this happen?

This is fairly common and is termed Non-Recognition Aggression, cats rely on scent to recognize each other. Her visit to the hospital has changed her scent to the point where her brother can no longer recognize. A few theories behind it are:

• The cat expressed his/her anal glands or is emitting pheromones associated with stress.
• The cat took home scents of other animals who were previously at the clinic

What to do?

It is a good idea to keep them separated in the meantime for each others protection. A few things that can help:

1. Giving blankets with each others scent to opposite cats (i.e brothers blanket goes with sister and vice-versa)
2. Feliway Friends

After 24 hours try to gradually re-introduce them, either by opening the door a crack for them to sniff or to have a gate in between. It does self-resolve after some time you just need to make sure the conflict is over before putting them in the same room.

How can I prevent this?

Next time, if possible, bring both cats to the hospital - they won't lose sight of each other.