Fighting Sibblings

Question
I have two cats, one male and one female and they are sibbling litter mates. They are 12 weeks old and have been living with me for about a month. Recently I have began to notice that the male's whiskers are broken on one side of his face, all that remains are little half whiskers. I have also noticed that he is missing a little chunk of hair by his ear. Today when I got home from a movie, I quickly noticed that his eye is all red and bloodshot. I have noticed that when the two cats play the female is very rough with her brother and often makes him squeak. The male is also much smaller that her sister and I am afraid that she is really hurting him! The male is also very withdrawn and tends to spend most of his time hiding curled up in a ball somewhere. I am nto sure what to do! Should I separate them when I am not home? I don't want her to hurt him and I want him to be sociable. When he is not around her he is definately more loving then when she is around. Please help!

Answer
Hi Jessica,

I would suggest you try a product called Feliway Comfort Zone. It mimics cat's happy pheromones. See if this calms her down. She is developing aggressive behaviors that if not checked now could lead to major problems later. Let me know if this works. If it doesn't write back. Keeping them separate is an option. You might want to talk to your vet at how young he spays at. This will also help. Good luck.