Former senior racing executive Matt Rudolph has lost an appeal against a disqualification for his conduct in the Sam Kavanagh cobalt case.

In November, a Racing NSW Board sub-committee disqualified Rudolph for two years after finding he acted improperly and tried to influence the trainer to change his evidence to stewards about the source of a substance containing high levels of cobalt.

Kavanagh had told stewards that Melbourne vet Tom Brennan, a long-time friend of Rudolph, was the supplier of "Vitamin Complex", a substance found to contain high levels of cobalt.

Rudolph and Kavanagh's father, fellow trainer Mark Kavanagh, met with Sam Kavanagh at a Sydney hotel where the younger Kavanagh said he was pressured to change his evidence about Brennan.

Rudolph worked in a senior position at the Australian Turf Club at the time.

The inquiry was sparked by illegal levels of cobalt found in a swab taken from the Sam Kavanagh-trained Midsummer Sun after he won the Gosford Cup in January, 2015.

Sam Kavanagh and Brennan have both been disqualified while Mark Kavanagh and fellow trainers Danny O'Brien and Lee and Shannon Hope face cobalt charges in Victoria.

In dismissing Rudolph's appeal, the NSW Racing Appeals Tribunal said while it upheld the conviction, it had made no decision on penalty.

Submission on penalty can be made after the Tribunal gives its written reasons for dismissing the appeal against conviction.