It could also be his age. My cousin's cat, Mellow, has suddenly started attacking the dog (who he has known his whole life) and the other cat (who they have had for almost 2 years). He just seems to be getting more and more grouchy with his age. He wants to be left alone and the mere presence of the other pets annoys him.
Reguardless what is causing it, chances are it is stress related. So focus on things to calm his stress. Anti-anxiety meds, that calming spray. Maybe giving him his own room in the house that the other pets are not allowed in. Things like that.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
1 Rat: (Ace)
1 RC Hamster: (Hannibal)
3 Cats: (Tao, Drew, Jak-ke)
2 Ferrets: (Fisher, Georgie)
1 Betta: (Maxwell) + (5 Platies and 1 Molly)
Rest in peace all my little Mice: Tempo, Aaron, Tatiana, Pei, Shi, Orange, Spotty, Lee Hyun, Key, Calvin, Chun, Jiro, Hero...
And my past Dookers: Lulu (my heart), Frodo (my old man), MoneyPennies (the first one), ect...
Aswell as all my lost Cats (my beloved Haru, ect..) and Bettas (Stahl the creepy one, ect..)