Why is your cat suddenly acting aggressive after meeting a different cat?

Answer 1

i have been doing much research in this department lately, as the same thing is happening at my house. what i have learned is that it is most likely a case of "misdirected aggression" meaning that something or someone has spooked one of your cats & he is now "taking it out" on your other cat. also there is a chance if the undeserving cat was out of the house (like at a vet visit) the cat that remained at home doesn't recognize the new smells attached to the cat that was away. i have been told to just try to act calm & normal & hopefully time will remedy the situation. they do sell a product at pet supply stores called Feliway or Rescue Remedy that helps these situations. it is a plug-in (like Glade) diffuser that provides "feline-friendly pheromones" to help the cats get reacquainted with each other. i am going to the store today to buy it. good luck to you!

Answer 2

because if the males are unneutered they will tend to fight. here are some reasons, terroitory, behavior, rights to copulate ( get a female pregnant) or just to plainly tussle hope this helps, silver123

Answer 3

your cat is territorial.... he/she is the dominate one of the two, so he needs his space. their dominance levels are competing and they aren't used to each others company yet. your cat needs to understand that they aren't the dominant one anymore. and when your cat doesn't listen pat his nose to get him to stop being aggressive. and trust me, this works... because my cat has done the same thing.. <3 welcome :)