Change on behaviour

Question
I have a 4 year old female British Shorthair. I bought from a pet shop when she was 10 weeks old. She was the most nervous cat I have ever had - she cringed when I tried to pat her and would run away and hide whenever I approached her. If I did manage to pick her up she seemed to emjoy affection but never seemed completely relaxed. About 2 months ago I had her desexed and her behaviour has changed comletely. She now comes to me for a cuddle and no longer seems startled all the time. She is happy to jump up on the lounge and sit next to me and no longer runs away at the slightest noise. She has also taken to walking around with a toy mouse in her mouth, calling out. While I am delighted that she finally seems to trust me and is a much happier cat, why would desexing bring about such a dramtatic change in her?  

Answer
Rosemary,

The simple fact is that entire cats are, in general, somewhat oversexed.  Those hormones can rage at any time of the year and will cause the usual calling behavior,  Couple that with the fact that she has never been bred (you never mentioned her having kittens), so she may also have had "female" problems.

Spaying removes the hormone raging issues as well as any possible "female" problems which may have caused her some discomfort on top of everything.  Cats in discomfort tend not to like to be petted or handled as much.

I am glad she is doing better after having been spayed.

Best regards... Norm.