What do you think killed my cat?

Probably a wild animal. Unless you saw it die, in which case it was most likely some virus or disease that was pretty painful.. Sorry for your loss.

Did you find your cat frozen in a hissing position or did you witness your cat die while hissing?

If the former, probably a wild animal as kissmysoul said. If the latter, possibly a heart attack or stroke (or blood clot). Either way your kitty is no longer in pain and had a good life while it was with you which was all it could ask for, s/he will rest in peace.

Sometimes when cats are dying, they become very scared and disoriented and begin to hiss. If you saw it die, it probably had an illness of some kind that was effecting it’s blood pressure. If it had had a cold (runny nose, matted eyes, and sneezing) before it died, it most likely had feline leukemia. If it did have those symptoms, keep an eye on any other cats you may have. Feline leukemia is very contagious.

Sorry to hear about your cat but I hope I helped. Sam

awww! dude. he/she probably choked on a hair ball and couldnt get it to come up and if it was to far up then it wont go down, there fore blocking it breathing. if its breathing passage way was blocked she/he might have freeked out and started hissing trying to get it to come out and probably choked. it was in destress as all cats are when they die but, im just giving some advice… sorry…