My new kitten hisses at my older cat. How can I make them friends?

Separate Lilly from the kitten for a few days. Gradually reintroduce them. Start with a closed door between them so they can hear and smell each other. Progress to seeing each other but without physical contact. Once they are acclimated, try short periods of supervised contact. Use a pheromone prodcut such as Feliway Spray or the plug in diffuser to decrease any anxiety or aggression.

Here is a great article on introducing a new cat to the household. https://www.petcoach.co/article/5-steps-to-introducing-your-cat-to-a-new-feline/ You might want to back up a few steps and try to start the introduction over from the beginning. The second thing you can try is to help Fiona deal with the anxiety of the new kitten by using Feliway, which is a cat pheromone that can be calming. It is available in a diffuser that is plugged into an outlet and is great for a room in the home. It is also available as a spray, which can be used on towels, or the most common locations Fiona likes to spend time. https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=8906 https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=37241 Another product I like is Composure, which is available as a little treat. https://www.petco.com/shop/en/petcostore/product/vetri-science-composure-feline-bite-sized-chews If these do not help, you might consider discussing prescription medication for anxiety with your veterinarian. Thanks for using PetCoach.

I would try a Feliway spray, diffuser or collar. It is a pheromone that helps with relaxation and anxiety. There are also supplements for anxiety. Set up separate areas for feeding and two litter boxes so they each have their own space with an area that they both have access to. Usually over time they will adjust if left alone. If she’s still aggressive there are prescription medications to give her for a little while to help her adjust so please discuss this with your veterinarian. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Kaji.

IT can be common for two cats to get along sometimes and not other just like children. The cats are working together to figure out perfect harmony in there environment. I would not be concerned unless you notice abnormal urination/defecation or you feel like the two cats are constantly fighting. IF they are having occasional disagreements that can just be normal pet behavior. If you feel the younger cat has a lot of energy I would recommend trying to increase play by hiding toys and treats around the house. Hope that helps

Well, Smickle IS king of the house! Actually just let him hiss away. Eventually the hissing will stop. This can take a good few weeks. Some day they will sleep on the same bed, but when they see you, will hiss anyway. Give him as much love as you used to, and make extra time for cat number two. Not every cat learns to love another cat, however almost all cats can learn to live in the same household. So Smickle is jealous now, but if you can manage to put lots of lovings on him, he will forgive you for bringing in another kitty, into his kingdom, and eventually the two will likely get along. It will take time and you cannot force it.

It does take time for the existing cat to get used to a new addition to the house, and I recommend introducing them slowly to each other. Take the kitten, and put her in her own room with her own food, water, and litter box. Keep the door closed, and for a few days, feed them both treats on other side of door so they associate each other's smell with a good experience. Then let the other cat in the kitten's room while the kitten is in a cat carrier. They can smell each other, but not be in contact. If either becomes upset or show signs of aggression, remove the second cat from the room, and try again later. Praise them when they interact appropriately. When they are interacting well with each other through the carrier, you can let the kitten out of her room, and see how she interacts with the other cat. Praise them when they interact appropriately, and separate them with any sign of aggression or upset. I would get a cat tree with lots of shelves to give the cats vertical space to get away from each other. I would keep the kitten in her room when you go out until they are comfortable with each other.

As long as Oliver is fully vaccinated, it would be fine to let them interact with supervision. The kitten is likely hissing out of instinct and won't necessarily attack Oliver. Usually the cats work out their differences in their own way, but you should be there in case they start acting aggressively towards each other. If they are starting to swipe at each other, then it would be best to give them a little more time separated before letting them interact again. Below is a link to an article with some good advice for introducing the two. https://www.petcoach.co/article/5-steps-to-introducing-your-cat-to-a-new-feline/ I hope that helps and all is well with Oliver and the new kitten.