Strange cat behavior

Question
I have had my male cat for around 10 years, he has been done.  He is the softest cat I have ever met with people and other animals ie dogs etc (he will fight with other cats and catches mice and birds)he has never scratched me, not even got his claws out, you could do anything with him and he wouldn't hurt you.  Until 2 nights ago that it.  He was sat at the side of me on my bed as usual and I was stroking him and he was stretching out to me when he suddenly sat up and started growling and hissing at the bottom of the bed.  I ignored it the fist time but all through the night he would be sat there then start growling for no apparent reason.  He let me stroke him around the head but not along his back, I thought he may have hurt his back or being hit by a car but he still seemed to move and jump up and down the fence and roof etc with no problem, he continued to be a bit quiet all day and went out.  He came back in (via bedroom window as normal)and cuddled up to me like his old self but later when I moved he growled and spat and then hid under the bed.  I got him out of my bedroom (he scares me now)and he has continued the behavior with my mother.  I had taken one of those long feather dusters and ran it along his back and he seems fine with that.  Is he just getting old and crabby or is there something more serious.

Answer
Hi
in cases like this where there doesn't seem to be any apparent cause for his change in behavior i always recommend a checkup at the vets.  Sometimes underlining illness like thyroid problems can cause behavior changes and the only way to check this is out is usually with a blood test.

It may be nothing medically wrong though but it is good to rule anything like that out first just in case.

if the vet finds nothing wrong then it could be that some thing has upset him while he was outside and he is feeling a little stressed by it which is making him a little more nervous and jumpy and the normal reaction to this is to be aggressive. If this is the case hopefully over time he will calm down again.

Unfortunately there is no definite answer i can give you regarding this as behavior changes can be caused by so many physical of mental changes. All i would say is get him checked out to at least rule out any possible medical problems, especially due to his age.

best wishes
Kate