Aggressive female cat

I adopted a female 13 year old yellow tiger back in July. She has been snitty toward my 16 year old male cat, scratching him in the face several times now. My house is about 3800 square feet and I bought one of the felliway plug in dispensers. I realize the one doesn't cover this big of a house but I'm not sure it would work anyway. They go outside a little bit while I am out there (she goes out on her own to roam a little...can't really change her personality) and she went after him twice outside today. My male is a sweet and gentle cat and I don't want him to have to cower all of the time.
I seem to remember reading something about a shot(hormone?) given to older female cats that would make them not so snitty. Does anyone know about a shot that would do this or have any other ideas?

Meower -
It's not unusual for cats to act territorial - that's their nature. Most of the time, even if they don't become great friends, they will learn to tolerate each other, especially when there is a lot of space for them, as there is in your house.

Sometimes cats that act aggressively are actually scared - your newer cat's 13 and even for young cats, a new home, new people and a new cat "sibling" to get used to can be a bit much, especially so for an older kitty. Just wondering how you introduced the cats to each other and if the newer kitty has been behaving this way from the beginning.

For cats with severe anxiety problems, and sometimes that's what aggressive behavior is, there are drugs available. Busparin is one that I used years ago on a *short term* basis, for one of my cats. I understand there are others available. However, you don't want to use drugs unless it's a last resort.

In the meantime, keep your tiger's nails trimmed short, and separate her and your older kitty when you're not around to supervise. One of the great former moderators on TCS, the wise Hissy, used to suggest a tiny drop of vanilla extract under the chin of each cat. The thought was that if the cats smell the same as each other, and therefore familiar, it will lessen the hostile behavior.

If you do a search in the Behavior forum on introducing cats to each other, you'll find many suggestions that may help. Your new cat has only been with you a few months, and with time the situation is likely to improve.

I have to say that even though things aren't going so smoothly right now with your cats, you did a wonderful thing adopting an older kitty, and I congratulate you for doing something I wish more people would do.

How about putting Soft Paws on her so when she scratches the 16 year old cat, she doesn't do any damage.

What are soft paws?

The cat I have adopted probably does have anxiety problems. The first time I met with her in the get acquainted room, I began to pet her and she took a swat at me and wouldn't let me touch her anymore. The smells in the enclosed get acquainted room were just too much for her. Since my daughter really wanted her, we went back and looked at her again. They put her in an office with us and she was very loving.
She is a very interesting cat, she has attacked my dog when she thought the dog was attacking my daughter(dog and child were playing and the dog was barking). She has really attached to my daughter because she sleeps with her. Tiger can't handle too much stimulation...she starts to swat. I am actually afraid to trim her nails. I would love to have her declawed but I know that isn't a good thing. She has scratched me a few times. She isn't the perfect cat since it seems she really needs to be the only cat. I think though if I took her back she would probably be PTS...she was at the Humane society for 5 months before I adopted her. I will probably give her a few more months and then talk to the vet about medication alternatives.