There are a few reasons why your 9-month-old Siamese cat may be acting aggressively toward your new 5 Persian cat.
1. Territorial aggression: Siamese cats are known to be territorial, and the introduction of a new cat into the household may be seen as a threat to his territory. This can lead to aggressive behavior, such as biting and chasing.
2. Unresolved dominance issues: Although both of your cats are neutered, there may still be some lingering dominance issues between them. This is especially likely if the Siamese cat is older than the Persian cat. In an attempt to establish his dominance, the Siamese cat may resort to aggression.
3. Misdirected aggression: Sometimes, cats will redirect their aggression towards another animal or object when they are feeling stressed or anxious. This could be the case if your Siamese cat is feeling overwhelmed by the presence of the new Persian cat.
4. Medical issues: In rare cases, aggression in cats can be a sign of an underlying medical condition, such as hyperthyroidism or brain tumors. If your cat is displaying sudden changes in behavior, it is important to take him to the vet to rule out any medical problems.
Here are some tips for reducing aggression between your two cats:
*Separate the cats for the time being. This will give them both a chance to calm down and de-stress.
*Provide each cat with their own food, water, and litter box. This will help to prevent any competition for resources.
*Gradually reintroduce the cats to each other in short, supervised sessions. Start by allowing them to see each other through a closed door or pet barrier. Once they are comfortable with this, you can start to let them interact for short periods of time.
*Reward both cats with treats or praise when they interact positively with each other.
*Consult with a veterinarian or animal behaviorist if the aggression continues. They can provide you with further guidance on how to manage the situation.
With patience and understanding, you can help your two cats learn to live together peacefully.