behavior of my oldest male cat

Question
my oldest male cat has all of a sudden became very aggressive towards his younger bother who is not fix but not spraying at this time

Answer
Hi
This is a common cat reaction to another male cat regardless of their relationship with ech other. Cats retain all their natural instincts and things like territory and male dominance will play an importnat role in their lives.

the fact that your male cat is not neutered will mean that he will be giving off strong male scents in his urine even if he is using a tray and this smell will pose a threat to your other male cat. So his behavior is quite normal as he is trying to assert himself as top cat in the home.

The only way to calm the situation would be to have the other cat neutered as well then he will not pose so much of a threat to your older cat.

best wishes
kate