Integrating new cats and kittens with existing cats and kittens is almost always a very stressful event for everyone – the cats involved, as well as the human the cats belong to.
Cats are very territorial and rub their phermones everywhere around the house that they live in.
When new cats are adopted or rescued and brought in, the existing cats view this as an invasion of their property most of the time. Not all cats react in an adversarial manner though. It’s really a matter of carefully introducing them to each and and observing how it goes. Then take measures on the fly depending on the reactions of the cats and kittens involved.
Here’s a video of 10 different cats and kitten meeting for the first time? Will they hiss or will they kiss? Watch to find out!