Queensland stewards have again warned trainers about ensuring their horses do not have access to wood shavings or wooden posts which have been treated with arsenic.

There have been at least eight cases in the past 18 months in Queensland where trainers have been charged after their horses returned positive samples to arsenic.

Trainers in other states have also been charged with arsenic-related offences.

While in most cases there were no penalties imposed on trainers stewards have warned horses will be disqualified and lose any prize money.

In the latest case stewards opened an inquiry after a sample taken from Tactical Manuever, who won at Warwick on March 9, indicated the presence of arsenic.

Tactical Manuever's trainer Rob Davidson pleaded not guilty to a charge of bringing a horse to race with a prohibited substance in its system.

In finding against Davidson, stewards considered a study by the Melbourne University faculty of Veterinary Agricultural Sciences examining the ingestion of wood shavings containing arsenic and the elevated levels achieved in tests.

The stewards could not exclude the level of arsenic was not the result of Tactical Manuever consuming wood shavings from timber posts used in the stable.

Analysis of the wood samples from the stable confirmed the presence of arsenic

There was no other evidence of any products containing arsenic being administered and stewards did not impose a penalty on Davidson but Tactical Manuever was disqualified from her first placing.