Where did Otto go Mama?

It has been almost a year since our precious Otto passed away of bloat, but Blake still randomly asks about him.  I try to be as honest as I can without being overly honest, but it is just so confusing for the little man... Blake is in the "Why Mama?" stage, so dodging a question about anything is hard to do.  He doesn't understand why we can't go and get Otto from Heaven, he asks why he left, and then he asked me if he made Otto sad and that is why he left?  I told him that it wasn't anything that anyone did, it was just his time.  I told him that Otto went to heaven and that it is not a place that we can go visit.  I then told him that Heaven is a very special place, and that it takes a lot of really hard work to get there.  I asked him to remember how Otto always played with him and let Blake roll all over him, and he said that he remembered.  So I told him that Otto worked so hard his entire life to be good to the people that he loved, and when he got really old, god let him go to Heaven so that he could rest.  I don't know if I got anywhere with him because he looked at me again and then said, "I want to go see him"  I cant believe that he really remembers him.  It just goes to show what an impact a dog can have on a child's life...what a friend they can be.  I can honestly say that our life was better having Otto in it, and he is missed very much, and almost a year later, it is still hard to think about.