Why did Phar Lap die?

Phar Lap did die of poison but it was accidental. A paddock a couple of yards away had been sprayed with poison to kill weeds and it had been blown by the wind into his paddock and the grass. Phar Lap must have eaten some of the grass with the poison that had been blown and died hours later. Scientists discovered this recently and decided that this was the reason why Phar Lap died.