Chater Mikado, at Sha Tin while in the stalls. They believe he had a heart attack.
Only 4 he had raced in Randwick and Rosehill as The Mikado.
This is his only HK win...
http://racing.hkjc.com/racing/info/m...20111023/HV/09
"He was standing in there for a while and he was very quiet, then he gave one little twinge and didn't move. That was when I got off him because I thought he was about to rear and flip over, but he stayed leaning against the side of the stall and one of the barrier attendants told me he was dead. I didn't believe it but they said it again. It happened very quickly." - Zac Putron