The long-running cobalt case involving Danny O'Brien and Mark Kavanagh continues, with Racing Victoria seeking leave to appeal a Victorian Civil and Administrative Tribunal ruling which cleared the trainers.

O'Brien and Kavanagh last month had four and three-year bans, respectively, quashed by VCAT on appeal.

Racing Victoria had 28 days to decide whether to take the matter further and on Thursday announced it is seeking leave to appeal the VCAT decision to the Court Of Appeal of the Supreme Court of Victoria.

"RV is seeking leave to appeal on the proper interpretation of Australian Rule of Racing (AR) 178D, which led to VCAT determining that tests showing cobalt above the permitted threshold in horses trained by Mr O'Brien and Mr Kavanagh were inadmissible," an RV statement said.

"RV is also seeking leave to appeal on the interpretation of 'cause' under AR 175(h)(i) and AR 175(h)(ii) so as to determine the appropriate level of responsibility of the licensed trainers for the management of their horses and their service providers."

In January last year the Racing Appeals and Disciplinary Board disqualified O'Brien for four years after four horses in his stable returned race day samples above the allowed cobalt threshold in the second half of 2014.

Kavanagh received a three-year ban after one of his horses tested above the threshold.

They took their cases to VCAT, while continuing to train under a stay of proceedings, and Justice Greg Garde dismissed the charges against the trainers last month.

The judge said there was a problem with the evidence that Racing Victoria had relied on.

"The tribunal finds that over the period of April 2014 until August 2015, the procedure for testing for cobalt substantially departed from the requirements," Justice Garde said.

"The test results are inadmissible as evidence against the trainers."

The Tribunal was not satisfied either Kavanagh or O'Brien caused veterinarian Dr Tom Brennan to administer the substance labelled 'vitamin complex' or were aware it was being administered to the horses in question.

RV's acting chief executive Giles Thompson said RV believed it was appropriate to appeal the VCAT decision.

"Racing Victoria must pursue its core focus of the protection of the integrity of our sport and welfare of our horses," Thompson said.

"We believe it is appropriate that Racing Victoria seeks an appeal of VCAT's decision."