change in behavior of cat

Question
My cat is about 6 years old. She is not spayed but is an indoor only cat. I have
three other cats who are spayed and neutered. I also have two dogs who are
about 7 years old. My problem started about 3 weeks ago. My cat, Macey gets
very cuddly and maternal about a week before she goes into heat. I am
familiar with her patterns as I have had her since she was only 6 weeks old.
She has lived with our dogs for 6 years with no problems. She doesn't
socialize with them but doesn't bother them either. Anyway out of the blue
she attacked both of our dogs which are dalmation mixes and not small dogs.
The dogs didn't know what to do and I was shocked. I was able to grab the
cat and I but her in my room until she calmed down. I put the dogs in their
crates to give them some time to calm down also. I let my cat out a few
minutes later and she came and sat on my lap happily purring. My son's
friend stopped by and just peaked in to say hi to me when my cat leaped of of
me and attacked him. She had never done anything like that before. Again I
put her in my room. After my son's friend left the room I let her out again.
Once again she jumped up on my lap and started purring. My son came a
couple of hours later to talk and she attacked him. She hasn't attacked any
more people but she continues to attack the dogs and I am afraid of what
might happen. The dogs will only take so much abuse. I don't know how to
stop her. Like I said she has lived peacefully with everyone for 6 years. I have
noticed that she seems a little more sensitive to loud sounds lately and if I
call to someone in another room she gets upset. Also it seems like her heat
cycles are lasting longer. I'm not sure if any of this has anything to do with
her behavior but somehow I need to find a solution. I don't want to spay her
as I'm afraid of what it will do to her weight. Thanks for any advice.

Answer
Chris,

First of all, she should be spayed.  If she has had many heats and has not been bred, she could be having medical problems.

Changes in behavior that you are seeing could be due to a number of problems.  First she may have a medical problem causing her some pain, in which case she could have behaviors that lash out at others in response to the pain.

There could be a new cat in the neighborhood she is seeing through the window and upsetting her tremendously. This could also bring about this behavior.  

I would have her checked by the vet and consider spaying her to see if things calm down.

Please let me know what you find out.

Best regards... Norm.