Father and son training partners Lee and Shannon Hope have pleaded guilty to a lesser charge of administering cobalt, arguing it was inadvertent.

They deny administering cobalt to affect the performance of three horses in races in 2014, a more serious charge still being pursued by Racing Victoria.

They have pleaded guilty to the lesser charge of administering a prohibited substance with their barrister saying the defence case was there was an inadvertent administration.

There was no intent to exceed the cobalt threshold to affect the performance of a horse in a race, the defence told the Victorian Civil and Administrative Tribunal on Monday.

Lee and Shannon Hope are appealing their respective three and five-year disqualifications for administering cobalt to affect the three horses’ performances.

Credit: AAP