A dog belonging to the head of Greyhound Racing New Zealand has been found with morphine in its system.
A spokesperson says the morphine was identified in a sample from Miss Gigi owned by chairman John MacArthur.
The group suspects it might have come from poppy seed in bread the dog ate.
But Greyhound Protection co-founder Aaron Cross says morphine is commonly used to mask injuries in racing dogs.
Mr MacArthur will remain chairman of Greyhound Racing New Zealand, but has resigned from his position at the Racing Integrity Unit - which describes itself as an independent body for drug testing in the industry.