My cats behaviour!

Question
My cat is a 6 year old spayed female. She always has quick mood changes but had never been aggressive. She doesn't play with toys, preferring to play with hands, and she likes to have a cuddle, but for the first time ever, she was aggressive. I put her down about a meter from the back door, and she ran under a table. When I tried to get her out, she hissed and screeched at me, and swiped for my hand in a similar way that a big cat would to a rival big cat. It took me ten minutes of fighting to get a grip on her, but she was still scratching and hissing at me. She's never behaved like this before, I'm extremely worried about her. Could she be ill?

Answer
Mel,

Abrupt mood changes, especially aggression, may be due to a medical issue.  I would have her checked by your veterinarian. Cats in discomfort will often behave in this way.

Another possibility is that she is seeing a strange cat through a window and reacting to that.  Usually, in this case, the cat should be put in an interior room (i.e. no windows to the outside) for a couple of hours letting her calm down.  When cats are in fight/flight/fright mode they are so intensely focused on the possible threat, they often forget themselves and everyone else!

Please let me know what you find.

Concerned regards... Norm.