After my friend was put to sleep

Question:
 I have just had my cat called sophie put to sleep on the recomendation of the vet.Sophie was 19yrs of age and had slept on my bed for most of them years.In the recent months her loss of weight and thirst for water where dramatic,also she was having trouble eating due to her loss of teeth.The vet told me that a certain test had shown it to be 60 when it should of read 10 and that this was way to high for her and the most humane thing was to have her put to sleep.I could not beleive it,I know that 19 is a good age but the shock of losing my little friend had finally dawned on me. I arranged for the vet to come around five days later which was her first availble home visit,I made sure my daughter was at school and my wife was at work.I will be brief and to the point now, but after sophie was put to sleep I had already arranged within the hour to take her to the cremotorium.Everything happened so quick and i feel so terribly sad and guilty that I had contact somebody. When the vet had injected her she tried on one leg but had to try on another,at this time she had already been sedated.This is where my mind and problem is.After the vet had left I could hardly breath as I had loved that cat so much,I went back into the room where she lay and kissed her goodbye and stroked her only to here a noise.I have got this reoccuring thought in my head that I can not get rid of and that is what if my little friend who trusted me so much that I held her for the sedation had not been put to sleep properly and with my haste to get everything sorted before my family got home i let her down in the most horrible way possible and that she was still alive in some way.i know it sounds crazy and the vet checked her heart for a pulse but do noises come from animals when they are put to sleep? It is only the third day since sophie has left me and I have felt grief before,but this is as strong as any i have.I have a wonderful family who I would not discuss this with,but the thought that she might not of been dead and met a terrible ending just won't leave me can somebody please help.
Answer:
 oh sweetie, i am so sorry for the loss of your sophie,but please please do not torture yourself.right now you need your own support more than you need anyone elses.i know that no matter how many people tell you no matter how many ways your told some small part of you will hold on to the guilt you feel but please believe me you should not.every living being continues to have air escape it,s body after death many times this will create noise there is often times even movement after death,this is just the the body shutting down.nothing not even a machine just stops when turned off it is more like a winding down of things.you did everything right for you and your sophie and your family.you were there for her in her own home holding her as she fell asleep one last time.how much better could it be than that.she was 19yrs old and i am sure she had an amazing life with you and in death she was allowed simply to pass on as opossed to slowly deteriorateing.isn't that what you would wish for yourself.tell yourself over and over until you believe us both that this is a natural occurance in death and that you did everything right.feel better and try to talk with your wife,you need to be there for eachother and to do that you need to let eachother in even to the places you are afraid might hurt.she cannot comfort you if she does not know you need comforting and i'm sure she would agree with me...you were perfect and selfless in all of your actions.kyena's mom
Answer:
 you're welcome sophie's dad.i hope it helped.i know when kyena died even though i watched his body stopping i still thought he was breathing or moving every now and then.almost had a break down leaving him to be cremated...what if he's not really dead, thoughts.just irrational wishful thinking.take care.