I had my female cat neutered the other day. Problem is that when I brought her home, my male neutered cat started hissing at her. Now this I expected, but it is carrying on. My female cat is absolutely petrified now. I even found her hiding in the Litter tray! I thought the male cat would get used to her smell again, but it doesnt seem to be happening. Before they would happily play together and I dont think she can understand why her friend is suddenly hissing at her, What do I do?