At a Racing Integrity Board penalty hearing on Monday, the Darfield-based trainer was facing a disqualification of 12 to 18 months.
His dog Alpha Riley was found to have the drug in its system after routine testing.
Investigators also say another dog, Impressive Isla, was found in "clear and visible pain and distress" in October last year.
McInerney was also investigated in 2022 after handing 11 greyhounds over to a rehoming kennel. Eight presented with severe signs of neglect and mistreatment.
He has previously been prosecuted and fined after five of his dogs suffocated to death inside a van on a Cook Strait crossing.
He also has a long history of his dogs testing positive for banned substances, with incidents occurring in 1997, 2001, 2010, 2013, 2017 and 2023.
Animal rights group SAFE says the greyhound racing system in New Zealand is "clearly not working and a ban on the industry is overdue".
"Greyhounds are abused again and again and by the same trainers, and the penalties do nothing, the group's campaign manager Anna de Roo said.
"It’s not surprising that that both Labour and National committed to banning greyhound racing in the leadup to the election. It’s the only way to protect greyhounds."
The latest charges against McInerney are part of a broader pattern of abuse within the industry, she said.
"Just four months ago another trainer was charged after throwing a greyhound with enough force that they hit their head on the back of a kennel, and throwing another greyhound a metre from the lure," she said.
"This trainer also had a previous methamphetamine charge. The industry is rife with harm and abuse. Once greyhounds are treated as commodities, animal welfare goes out the door."
De Roo said the public overwhelmingly supports a ban on the industry, with an independent poll stating 74 per cent of New Zealanders would vote to ban greyhound racing in a referendum.
"The end to greyhound racing can’t come soon enough. Incoming Prime Minister Christopher Luxon has already committed to banning greyhound. As soon as a new government is formed, they must take urgent action to protect greyhounds."
Greyhound Racing NZ chief executive Edward Rennell told Newshub: "There is no place in our industry for those who breach animal welfare standards, or for those who use drugs like methamphetamine in the vicinity of racing dogs."
He said racing greyhounds were regularly drug tested and there had never been a case of deliberate administration of methamphetamine to a racing dog, only meth contamination.
It was not clear yet how the dog was contaminated but the hearing was told McInerney's son, who looked after the dogs, had a history of drug issues.
With McInerney disqualified, Newshub reported work had begun to transfer ownership of the dogs to his other son.
