Why is my indoor cat attacking the other after being outside?

Thanks for using Petco Pet Education Center, formerly Petcoach! This is possibly because she smells differently. I recommend a product called Feliway which can help decrease stress and anxiety associated with environmental changes and stressors. You may find this online or at your local pet store. It usually works great in this type of scenarios. Good luck and have a great day!

Thank you for contacting Petco Pet Education Center, formerly Petcoach with your question about Oliver. He is a very handsome boy!!! So regal. I suspect he smelled or saw something that upset him over at the neighbors and expressed redirected aggression at you when you grabbed him. Redirected aggression is when a cat lashes out at something else when they cannot lash out at the target that originally caused them upset and anger. For now, I’d keep him indoors at all times. He should stop the hissing over the next few days as he calms down. I hope this helps!

Cats can behave like this after any separation (even just as short as a trip to the vet). Generally this behavior will calm down. For now, separate food, water and litter box so that there is not competition. Also try a pheromone diffuser in the house to see if this helps to calm them down. Separate them if things become too aggressive and then reintroduce once they have calmed down. Best of luck with Lucy.

Hi and thanks for posting on Petco Pet Education Center, formerly Petcoach! If Milo has stayed for the week with your brother or sisters cats whom Milo has never met before while you were away, it possible those cats did not like Milo very much or became stressed with a new cat in their home. If Milo use to get along with your brother/sister's cat before, perhaps you leaving triggered the stress and aggression of the other cats. Cats do not do well with change and can really become stressed when their owner's habits or environment changes suddenly. It is best is Milo is kept at distance from your brother and sister's cats as much as possible for several weeks and then try slowly reintroducing them with a few short introduction sessions under supervision. Feliway pheromone spray diffusers around the house can work on easing tension. I hope this helps and best of luck to you and Milo!

Cats will often do this if they have been separated for a period of time, especially if one cat looks or smells different - your female cat may have strange smells on her from her time outside. Most of the time, this reaction is mild and the cats will get along again after a day or two. If there is any serious fighting or if his aggressive behavior towards her does not seem to be improving, then you may need to separate them and gradually reintroduce them to each other - feel free to ask for additional help on this if needed :)

This happens quite a bit actually. Could be territorial aggression - she left and now he is trying to tell her the house is his OR it could be that he feels threatened due to the way she smells when she returns. I suggest you start using some Feliway products. I would spray the carrier when you take the cats to the vet and use the diffusers (multicat) in the house. ( https://www.feliway.com/us ) ( https://www.feliway.com/us/Why-Use-Feliway/how-to-stop-cats-fighting )

Great question! Washing Rikku and Lucy will have changed their smell, and they now see each other as strangers. I would separate the cats, and slowly reintroduce them to each other. Take Lucy, 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 Rikku into Lucy's room while she 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 him 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 her out of her room, and see how she interacts with him. 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 Lucy in her room when you go out until they are comfortable with each other. I hope this helps, good luck!