I have two cats that are litter mates. One is male the other female. The male has become very aggressive toward the female. He stalks her, chases her and will even get her down and bite her. He is much larger than she is and she has become very skittish in her behavior. She will watch for him constantly and sit with her back to a wall or somewhere where he can't sneak up on her. This problem has been getting worse for the past 3 months. She is getting more and more afraid of him and I need to know how to protect her!
You don't say how old these cats are or whether or not they have been spayed and neutered. If they have not been, that is the first place to start. The male will have much less tendency to be aggressive once he is neutered.
If they have both been spayed/neutered, then my next thought is that the male is really enjoying entertaining himself by beating up on his sister. A couple of things come to mind here: First, the more you can wear out the male by playing with him, the less he will entertain himself by stalking his sister. I would definitely try something like a "kitty-tease". A kitty-tease is a fishing pole-type of toy with a little bit of cloth at the end of the string. When drawn along the floor, or any surface, the little bit of cloth moves amazingly like a bug and kitties go nuts chasing it. I would try to play with the male several times a day and really wear him out. I would also play with him with the kitty-tease any time you notice him stalking his sister. Distracting him from annoying her by playing with you could solve the problem. Another thing that I have found works with cats who love to "attack" is a small stuffed toy about half-size to slightly smaller than the cat. A soft stuffed dog toy works great. These cats love to "attack" the toy, bite and kick it. Your male kitty sounds like he needs an outlet for his energy and desire to roughhouse.
The other possibility that comes to mind is that sometimes it works well to add to the family another young cat who loves to roughhouse. The two wild ones often play hard and wear each other out and leave the more sedate and timid cat in peace. Of course, adding an additional cat isn't always a possibility.
Besides trying to wear out your rambunctious male, I would try to put your female in a safe, quiet area away from the male when you are not home to supervise. With time and maturity, your male will probably begin to mellow. Until then, I hope these suggestions help.
This could also be territorial aggression. You need to separate your cats until you can get help . THis is a quality of life issue for your female and it not fair for her to constantly be looking over her shoulder - that creates a great deal of stress and can even lead to illness/medical problems.
We have a DVD called "Helping Kitties Co-Exist" available on our website www.HelpingKitty.com. Many behaviorists will do telephone consults for cat problems - find one at CertifiedAnimalBehaviorist.com. But the more opportunities your male has to harass your female, the better he gets at it, the more frightened she becomes and the chance for the cats getting along well decreases. So you need to separate them and then get a plan together - either from our DVD or hiring a consultant to help you.
This site complies with the HONcode standard for trustworthy health information.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.