That is horrible News about your Cat,as it could be poison,anti freeze,or FIV,and It might well,be worth,to have a test done,top see if you can anrrow,done the cause of death.I ma sorry,for your loss,and they are Eternal Kittens ,now,in the Pet Talkers Pet Angel Army,and will see you,.again,one day,and they say,not,to feel bad,that you did,all that you could,and they will,be your Kittens,again,one day.